Merge pull request #233 from 0xProject/feature/passNetworkId

Forces the users of 0x.js to pass the network id

60 files changed, 854 insertions, 2073 deletions

diff --git a/packages/0x.js/CHANGELOG.md b/packages/0x.js/CHANGELOG.md
index 81dddea53..67b2b89b6 100644
--- a/packages/0x.js/CHANGELOG.md
+++ b/packages/0x.js/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 vx.x.x
 ------------------------
+    * Make `ZeroExConfig` required parameter of `ZeroEx` constructor (#233)
+    * Add a required property `networkId` to `ZeroExConfig` (#233)
+    * Make all `getContractAddress` functions, `zeroEx.exchange.subscribe`, `zeroEx.exchange.getZRXTokenAddress` sync (#233)
+    * Remove `ZeroExError.ContractNotFound` and replace it with contract-specific errors (#233)
     * Make `DecodedLogEvent<A>` contain `LogWithDecodedArgs<A>` under log key instead of merging it in like web3 does (#234)
     * Rename `removed` to `isRemoved` in `DecodedLogEvent<A>` (#234)
     * Modify order validation methods to validate against the `latest` block, not against the `pending` block (#236)
diff --git a/packages/0x.js/package.json b/packages/0x.js/package.json
index d60d7dabb..024cb0fe9 100644
--- a/packages/0x.js/package.json
+++ b/packages/0x.js/package.json
@@ -16,7 +16,7 @@
     "build": "run-p build:umd:prod build:commonjs; exit 0;",
     "docs:json": "typedoc --excludePrivate --excludeExternals --target ES5 --json $JSON_FILE_PATH $PROJECT_DIR",
     "upload_docs_json": "aws s3 cp generated_docs/index.json $S3_URL --profile 0xproject --grants read=uri=http://acs.amazonaws.com/groups/global/AllUsers --content-type application/json",
-    "lint": "tslint src/**/*.ts test/**/*.ts",
+    "lint": "tslint --project . 'src/**/*.ts' 'test/**/*.ts'",
     "test:circleci": "run-s test:coverage report_test_coverage && if [ $CIRCLE_BRANCH = \"development\" ]; then yarn test:umd; fi",
     "test": "run-s clean test:commonjs",
     "test:umd": "./scripts/test_umd.sh",
diff --git a/packages/0x.js/src/0x.ts b/packages/0x.js/src/0x.ts
index 85c2b7724..0616b3078 100644
--- a/packages/0x.js/src/0x.ts
+++ b/packages/0x.js/src/0x.ts
@@ -1,34 +1,35 @@
-import * as _ from 'lodash';
+import {schemas, SchemaValidator} from '@0xproject/json-schemas';
 import BigNumber from 'bignumber.js';
-import {SchemaValidator, schemas} from '@0xproject/json-schemas';
-import {bigNumberConfigs} from './bignumber_config';
 import * as ethUtil from 'ethereumjs-util';
-import {Web3Wrapper} from './web3_wrapper';
-import {constants} from './utils/constants';
-import {utils} from './utils/utils';
-import {signatureUtils} from './utils/signature_utils';
-import {assert} from './utils/assert';
-import {AbiDecoder} from './utils/abi_decoder';
-import {intervalUtils} from './utils/interval_utils';
+import * as _ from 'lodash';
+
 import {artifacts} from './artifacts';
+import {bigNumberConfigs} from './bignumber_config';
+import {EtherTokenWrapper} from './contract_wrappers/ether_token_wrapper';
 import {ExchangeWrapper} from './contract_wrappers/exchange_wrapper';
 import {TokenRegistryWrapper} from './contract_wrappers/token_registry_wrapper';
-import {EtherTokenWrapper} from './contract_wrappers/ether_token_wrapper';
-import {TokenWrapper} from './contract_wrappers/token_wrapper';
 import {TokenTransferProxyWrapper} from './contract_wrappers/token_transfer_proxy_wrapper';
+import {TokenWrapper} from './contract_wrappers/token_wrapper';
 import {OrderStateWatcher} from './order_watcher/order_state_watcher';
-import {OrderStateUtils} from './utils/order_state_utils';
+import {zeroExConfigSchema} from './schemas/zero_ex_config_schema';
 import {
     ECSignature,
-    ZeroExError,
     Order,
+    OrderStateWatcherConfig,
     SignedOrder,
+    TransactionReceiptWithDecodedLogs,
     Web3Provider,
     ZeroExConfig,
-    OrderStateWatcherConfig,
-    TransactionReceiptWithDecodedLogs,
+    ZeroExError,
 } from './types';
-import {zeroExConfigSchema} from './schemas/zero_ex_config_schema';
+import {AbiDecoder} from './utils/abi_decoder';
+import {assert} from './utils/assert';
+import {constants} from './utils/constants';
+import {intervalUtils} from './utils/interval_utils';
+import {OrderStateUtils} from './utils/order_state_utils';
+import {signatureUtils} from './utils/signature_utils';
+import {utils} from './utils/utils';
+import {Web3Wrapper} from './web3_wrapper';
 
 // Customize our BigNumber instances
 bigNumberConfigs.configure();
@@ -169,56 +170,48 @@ export class ZeroEx {
      * @param   config      The configuration object. Look up the type for the description.
      * @return  An instance of the 0x.js ZeroEx class.
      */
-    constructor(provider: Web3Provider, config?: ZeroExConfig) {
+    constructor(provider: Web3Provider, config: ZeroExConfig) {
         assert.isWeb3Provider('provider', provider);
-        if (!_.isUndefined(config)) {
-            assert.doesConformToSchema('config', config, zeroExConfigSchema);
-        }
+        assert.doesConformToSchema('config', config, zeroExConfigSchema);
         const artifactJSONs = _.values(artifacts);
         const abiArrays = _.map(artifactJSONs, artifact => artifact.abi);
         this._abiDecoder = new AbiDecoder(abiArrays);
-        const gasPrice = _.isUndefined(config) ? undefined : config.gasPrice;
         const defaults = {
-            gasPrice,
+            gasPrice: config.gasPrice,
         };
-        this._web3Wrapper = new Web3Wrapper(provider, defaults);
+        this._web3Wrapper = new Web3Wrapper(provider, config.networkId, defaults);
+        this.proxy = new TokenTransferProxyWrapper(
+            this._web3Wrapper,
+            config.tokenTransferProxyContractAddress,
+        );
         this.token = new TokenWrapper(
             this._web3Wrapper,
             this._abiDecoder,
-            this._getTokenTransferProxyAddressAsync.bind(this),
+            this.proxy,
         );
-        const exchageContractAddressIfExists = _.isUndefined(config) ? undefined : config.exchangeContractAddress;
         this.exchange = new ExchangeWrapper(
             this._web3Wrapper,
             this._abiDecoder,
             this.token,
-            exchageContractAddressIfExists,
-        );
-        this.proxy = new TokenTransferProxyWrapper(
-            this._web3Wrapper,
-            this._getTokenTransferProxyAddressAsync.bind(this),
+            config.exchangeContractAddress,
         );
-        const tokenRegistryContractAddressIfExists = _.isUndefined(config) ?
-                                                     undefined :
-                                                     config.tokenRegistryContractAddress;
-        this.tokenRegistry = new TokenRegistryWrapper(this._web3Wrapper, tokenRegistryContractAddressIfExists);
-        const etherTokenContractAddressIfExists = _.isUndefined(config) ? undefined : config.etherTokenContractAddress;
-        this.etherToken = new EtherTokenWrapper(this._web3Wrapper, this.token, etherTokenContractAddressIfExists);
-        const orderWatcherConfig = _.isUndefined(config) ? undefined : config.orderWatcherConfig;
+        this.tokenRegistry = new TokenRegistryWrapper(this._web3Wrapper, config.tokenRegistryContractAddress);
+        this.etherToken = new EtherTokenWrapper(this._web3Wrapper, this.token, config.etherTokenContractAddress);
         this.orderStateWatcher = new OrderStateWatcher(
-            this._web3Wrapper, this._abiDecoder, this.token, this.exchange, orderWatcherConfig,
+            this._web3Wrapper, this._abiDecoder, this.token, this.exchange, config.orderWatcherConfig,
         );
     }
     /**
      * Sets a new web3 provider for 0x.js. Updating the provider will stop all
      * subscriptions so you will need to re-subscribe to all events relevant to your app after this call.
      * @param   provider    The Web3Provider you would like the 0x.js library to use from now on.
+     * @param   networkId   The id of the network your provider is connected to
      */
-    public async setProviderAsync(provider: Web3Provider) {
-        this._web3Wrapper.setProvider(provider);
-        await (this.exchange as any)._invalidateContractInstancesAsync();
+    public setProvider(provider: Web3Provider, networkId: number): void {
+        this._web3Wrapper.setProvider(provider, networkId);
+        (this.exchange as any)._invalidateContractInstances();
         (this.tokenRegistry as any)._invalidateContractInstance();
-        await (this.token as any)._invalidateContractInstancesAsync();
+        (this.token as any)._invalidateContractInstances();
         (this.proxy as any)._invalidateContractInstance();
         (this.etherToken as any)._invalidateContractInstance();
     }
diff --git a/packages/0x.js/src/artifacts.ts b/packages/0x.js/src/artifacts.ts
index 447f9880a..de2030812 100644
--- a/packages/0x.js/src/artifacts.ts
+++ b/packages/0x.js/src/artifacts.ts
@@ -1,11 +1,13 @@
-import {Artifact} from './types';
-import * as TokenArtifact from './artifacts/Token.json';
-import * as ExchangeArtifact from './artifacts/Exchange.json';
 import * as EtherTokenArtifact from './artifacts/EtherToken.json';
+import * as ExchangeArtifact from './artifacts/Exchange.json';
+import * as TokenArtifact from './artifacts/Token.json';
 import * as TokenRegistryArtifact from './artifacts/TokenRegistry.json';
 import * as TokenTransferProxyArtifact from './artifacts/TokenTransferProxy.json';
+import * as ZRXArtifact from './artifacts/ZRX.json';
+import {Artifact} from './types';
 
 export const artifacts = {
+    ZRXArtifact: ZRXArtifact as any as Artifact,
     TokenArtifact: TokenArtifact as any as Artifact,
     ExchangeArtifact: ExchangeArtifact as any as Artifact,
     EtherTokenArtifact: EtherTokenArtifact as any as Artifact,
diff --git a/packages/0x.js/src/artifacts/EtherToken.json b/packages/0x.js/src/artifacts/EtherToken.json
index 91b23bc94..8c1d0f499 100644
--- a/packages/0x.js/src/artifacts/EtherToken.json
+++ b/packages/0x.js/src/artifacts/EtherToken.json
@@ -233,213 +233,18 @@
       "type": "event"
     }
   ],
-  "unlinked_binary": "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",
   "networks": {
     "1": {
-      "links": {},
-      "events": {
-        "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef": {
-          "anonymous": false,
-          "inputs": [
-            {
-              "indexed": true,
-              "name": "_from",
-              "type": "address"
-            },
-            {
-              "indexed": true,
-              "name": "_to",
-              "type": "address"
-            },
-            {
-              "indexed": false,
-              "name": "_value",
-              "type": "uint256"
-            }
-          ],
-          "name": "Transfer",
-          "type": "event"
-        },
-        "0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925": {
-          "anonymous": false,
-          "inputs": [
-            {
-              "indexed": true,
-              "name": "_owner",
-              "type": "address"
-            },
-            {
-              "indexed": true,
-              "name": "_spender",
-              "type": "address"
-            },
-            {
-              "indexed": false,
-              "name": "_value",
-              "type": "uint256"
-            }
-          ],
-          "name": "Approval",
-          "type": "event"
-        }
-      },
-      "updated_at": 1502488087000,
       "address": "0x2956356cd2a2bf3202f771f50d3d14a367b48070"
     },
     "3": {
-      "links": {},
-      "events": {
-        "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef": {
-          "anonymous": false,
-          "inputs": [
-            {
-              "indexed": true,
-              "name": "_from",
-              "type": "address"
-            },
-            {
-              "indexed": true,
-              "name": "_to",
-              "type": "address"
-            },
-            {
-              "indexed": false,
-              "name": "_value",
-              "type": "uint256"
-            }
-          ],
-          "name": "Transfer",
-          "type": "event"
-        },
-        "0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925": {
-          "anonymous": false,
-          "inputs": [
-            {
-              "indexed": true,
-              "name": "_owner",
-              "type": "address"
-            },
-            {
-              "indexed": true,
-              "name": "_spender",
-              "type": "address"
-            },
-            {
-              "indexed": false,
-              "name": "_value",
-              "type": "uint256"
-            }
-          ],
-          "name": "Approval",
-          "type": "event"
-        }
-      },
-      "updated_at": 1506602007000,
       "address": "0xc00fd9820cd2898cc4c054b7bf142de637ad129a"
     },
     "42": {
-      "links": {},
-      "events": {
-        "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef": {
-          "anonymous": false,
-          "inputs": [
-            {
-              "indexed": true,
-              "name": "_from",
-              "type": "address"
-            },
-            {
-              "indexed": true,
-              "name": "_to",
-              "type": "address"
-            },
-            {
-              "indexed": false,
-              "name": "_value",
-              "type": "uint256"
-            }
-          ],
-          "name": "Transfer",
-          "type": "event"
-        },
-        "0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925": {
-          "anonymous": false,
-          "inputs": [
-            {
-              "indexed": true,
-              "name": "_owner",
-              "type": "address"
-            },
-            {
-              "indexed": true,
-              "name": "_spender",
-              "type": "address"
-            },
-            {
-              "indexed": false,
-              "name": "_value",
-              "type": "uint256"
-            }
-          ],
-          "name": "Approval",
-          "type": "event"
-        }
-      },
-      "updated_at": 1502391794392,
       "address": "0x05d090b51c40b020eab3bfcb6a2dff130df22e9c"
     },
     "50": {
-      "links": {},
-      "events": {
-        "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef": {
-          "anonymous": false,
-          "inputs": [
-            {
-              "indexed": true,
-              "name": "_from",
-              "type": "address"
-            },
-            {
-              "indexed": true,
-              "name": "_to",
-              "type": "address"
-            },
-            {
-              "indexed": false,
-              "name": "_value",
-              "type": "uint256"
-            }
-          ],
-          "name": "Transfer",
-          "type": "event"
-        },
-        "0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925": {
-          "anonymous": false,
-          "inputs": [
-            {
-              "indexed": true,
-              "name": "_owner",
-              "type": "address"
-            },
-            {
-              "indexed": true,
-              "name": "_spender",
-              "type": "address"
-            },
-            {
-              "indexed": false,
-              "name": "_value",
-              "type": "uint256"
-            }
-          ],
-          "name": "Approval",
-          "type": "event"
-        }
-      },
-      "updated_at": 1503318938233,
       "address": "0x48bacb9266a570d521063ef5dd96e61686dbe788"
     }
-  },
-  "schema_version": "0.0.5",
-  "updated_at": 1503318938233
+  }
 }
diff --git a/packages/0x.js/src/artifacts/Exchange.json b/packages/0x.js/src/artifacts/Exchange.json
index 734c8f9c7..25495a041 100644
--- a/packages/0x.js/src/artifacts/Exchange.json
+++ b/packages/0x.js/src/artifacts/Exchange.json
@@ -590,541 +590,18 @@
       "type": "event"
     }
   ],
-  "unlinked_binary": 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     "42": {
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-              "type": "uint8"
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-              "name": "orderHash",
-              "type": "bytes32"
-            }
-          ],
-          "name": "LogError",
-          "type": "event"
-        }
-      },
-      "updated_at": 1503318938231,
       "address": "0xb69e673309512a9d726f87304c6984054f87a93b"
     }
-  },
-  "schema_version": "0.0.5",
-  "updated_at": 1503318938231
+  }
 }
diff --git a/packages/0x.js/src/artifacts/Token.json b/packages/0x.js/src/artifacts/Token.json
index e922ff66d..a86f8228d 100644
--- a/packages/0x.js/src/artifacts/Token.json
+++ b/packages/0x.js/src/artifacts/Token.json
@@ -168,9 +168,5 @@
       "name": "Approval",
       "type": "event"
     }
-  ],
-  "unlinked_binary": "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",
-  "networks": {},
-  "schema_version": "0.0.5",
-  "updated_at": 1503317882695
-}
\ No newline at end of file
+  ]
+}
diff --git a/packages/0x.js/src/artifacts/TokenRegistry.json b/packages/0x.js/src/artifacts/TokenRegistry.json
index 5a0564a69..973a101e8 100644
--- a/packages/0x.js/src/artifacts/TokenRegistry.json
+++ b/packages/0x.js/src/artifacts/TokenRegistry.json
@@ -527,685 +527,18 @@
       "type": "event"
     }
   ],
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       "address": "0x0b1ba0af832d7c05fd64161e0db78e85978e8082"
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-  "schema_version": "0.0.5",
-  "updated_at": 1503318938228
+  }
 }
diff --git a/packages/0x.js/src/artifacts/TokenTransferProxy.json b/packages/0x.js/src/artifacts/TokenTransferProxy.json
index beeb16cfe..065343919 100644
--- a/packages/0x.js/src/artifacts/TokenTransferProxy.json
+++ b/packages/0x.js/src/artifacts/TokenTransferProxy.json
@@ -167,8 +167,18 @@
       "type": "event"
     }
   ],
-  "unlinked_binary": "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",
-  "networks": {},
-  "schema_version": "0.0.5",
-  "updated_at": 1503318938227
+  "networks": {
+      "1": {
+        "address": "0x8da0d80f5007ef1e431dd2127178d224e32c2ef4"
+      },
+      "3": {
+        "address": "0x4e9aad8184de8833365fea970cd9149372fdf1e6"
+      },
+      "42": {
+        "address": "0x087eed4bc1ee3de49befbd66c662b434b15d49d4"
+      },
+      "50": {
+        "address": "0x871dd7c2b4b25e1aa18728e9d5f2af4c4e431f5c"
+      }
+  }
 }
diff --git a/packages/0x.js/src/artifacts/ZRX.json b/packages/0x.js/src/artifacts/ZRX.json
new file mode 100644
index 000000000..7da67fde0
--- /dev/null
+++ b/packages/0x.js/src/artifacts/ZRX.json
@@ -0,0 +1,17 @@
+{
+  "contract_name": "ZRX",
+  "networks": {
+    "1": {
+      "address": "0xe41d2489571d322189246dafa5ebde1f4699f498"
+    },
+    "3": {
+      "address": "0xa8e9fa8f91e5ae138c74648c9c304f1c75003a8d"
+    },
+    "42": {
+      "address": "0x6ff6c0ff1d68b964901f986d4c9fa3ac68346570"
+    },
+    "50": {
+      "address": "0x25b8fe1de9daf8ba351890744ff28cf7dfa8f5e3"
+    }
+  }
+}
diff --git a/packages/0x.js/src/contract.ts b/packages/0x.js/src/contract.ts
index 7ccd336d6..e9c49c9f1 100644
--- a/packages/0x.js/src/contract.ts
+++ b/packages/0x.js/src/contract.ts
@@ -1,7 +1,8 @@
-import * as Web3 from 'web3';
-import * as _ from 'lodash';
+import {schemas, SchemaValidator} from '@0xproject/json-schemas';
 import promisify = require('es6-promisify');
-import {SchemaValidator, schemas} from '@0xproject/json-schemas';
+import * as _ from 'lodash';
+import * as Web3 from 'web3';
+
 import {AbiType} from './types';
 
 export class Contract implements Web3.ContractInstance {
@@ -47,7 +48,7 @@ export class Contract implements Web3.ContractInstance {
         });
     }
     private promisifyWithDefaultParams(fn: (...args: any[]) => void): (...args: any[]) => Promise<any> {
-        const promisifiedWithDefaultParams = (...args: any[]) => {
+        const promisifiedWithDefaultParams = async (...args: any[]) => {
             const promise = new Promise((resolve, reject) => {
                 const lastArg = args[args.length - 1];
                 let txData: Partial<Web3.TxData> = {};
diff --git a/packages/0x.js/src/contract_wrappers/contract_wrapper.ts b/packages/0x.js/src/contract_wrappers/contract_wrapper.ts
index c1c95c6db..8c92931b4 100644
--- a/packages/0x.js/src/contract_wrappers/contract_wrapper.ts
+++ b/packages/0x.js/src/contract_wrappers/contract_wrapper.ts
@@ -1,24 +1,25 @@
+import {Block, BlockAndLogStreamer} from 'ethereumjs-blockstream';
 import * as _ from 'lodash';
 import * as Web3 from 'web3';
-import {BlockAndLogStreamer, Block} from 'ethereumjs-blockstream';
-import {Web3Wrapper} from '../web3_wrapper';
-import {AbiDecoder} from '../utils/abi_decoder';
+
 import {
-    ZeroExError,
-    InternalZeroExError,
     Artifact,
+    BlockParamLiteral,
+    ContractEventArgs,
+    ContractEvents,
+    EventCallback,
+    IndexedFilterValues,
+    InternalZeroExError,
     LogWithDecodedArgs,
     RawLog,
-    ContractEvents,
     SubscriptionOpts,
-    IndexedFilterValues,
-    EventCallback,
-    BlockParamLiteral,
-    ContractEventArgs,
+    ZeroExError,
 } from '../types';
+import {AbiDecoder} from '../utils/abi_decoder';
 import {constants} from '../utils/constants';
-import {intervalUtils} from '../utils/interval_utils';
 import {filterUtils} from '../utils/filter_utils';
+import {intervalUtils} from '../utils/interval_utils';
+import {Web3Wrapper} from '../web3_wrapper';
 
 export class ContractWrapper {
     protected _web3Wrapper: Web3Wrapper;
@@ -95,6 +96,18 @@ export class ContractWrapper {
             await this._web3Wrapper.getContractInstanceFromArtifactAsync<ContractType>(artifact, addressIfExists);
         return contractInstance;
     }
+    protected _getContractAddress(artifact: Artifact, addressIfExists?: string): string {
+        if (_.isUndefined(addressIfExists)) {
+            const networkId = this._web3Wrapper.getNetworkId();
+            const contractAddress = artifact.networks[networkId].address;
+            if (_.isUndefined(contractAddress)) {
+                throw new Error(ZeroExError.ExchangeContractDoesNotExist);
+            }
+            return contractAddress;
+        } else {
+            return addressIfExists;
+        }
+    }
     private _onLogStateChanged<ArgsType extends ContractEventArgs>(isRemoved: boolean, log: Web3.LogEntry): void {
         _.forEach(this._filters, (filter: Web3.FilterObject, filterToken: string) => {
             if (filterUtils.matchesFilter(log, filter)) {
@@ -140,7 +153,7 @@ export class ContractWrapper {
             // We need to coerce to Block type cause Web3.Block includes types for mempool blocks
             if (!_.isUndefined(this._blockAndLogStreamer)) {
                 // If we clear the interval while fetching the block - this._blockAndLogStreamer will be undefined
-                this._blockAndLogStreamer.reconcileNewBlock(latestBlock as any as Block);
+                await this._blockAndLogStreamer.reconcileNewBlock(latestBlock as any as Block);
             }
         } catch (err) {
             const filterTokens = _.keys(this._filterCallbacks);
diff --git a/packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts b/packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts
index 3cd2f0224..7a3f2bc52 100644
--- a/packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts
+++ b/packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts
@@ -1,11 +1,13 @@
-import * as _ from 'lodash';
 import BigNumber from 'bignumber.js';
+import * as _ from 'lodash';
+
+import {artifacts} from '../artifacts';
+import {EtherTokenContract, ZeroExError} from '../types';
+import {assert} from '../utils/assert';
 import {Web3Wrapper} from '../web3_wrapper';
+
 import {ContractWrapper} from './contract_wrapper';
 import {TokenWrapper} from './token_wrapper';
-import {EtherTokenContract, ZeroExError} from '../types';
-import {assert} from '../utils/assert';
-import {artifacts} from '../artifacts';
 
 /**
  * This class includes all the functionality related to interacting with a wrapped Ether ERC20 token contract.
@@ -53,7 +55,7 @@ export class EtherTokenWrapper extends ContractWrapper {
         assert.isValidBaseUnitAmount('amountInWei', amountInWei);
         await assert.isSenderAddressAsync('withdrawer', withdrawer, this._web3Wrapper);
 
-        const wethContractAddress = await this.getContractAddressAsync();
+        const wethContractAddress = this.getContractAddress();
         const WETHBalanceInBaseUnits = await this._tokenWrapper.getBalanceAsync(wethContractAddress, withdrawer);
         assert.assert(WETHBalanceInBaseUnits.gte(amountInWei), ZeroExError.InsufficientWEthBalanceForWithdrawal);
 
@@ -67,9 +69,11 @@ export class EtherTokenWrapper extends ContractWrapper {
      * Retrieves the Wrapped Ether token contract address
      * @return  The Wrapped Ether token contract address
      */
-    public async getContractAddressAsync(): Promise<string> {
-        const wethContract = await this._getEtherTokenContractAsync();
-        return wethContract.address;
+    public getContractAddress(): string {
+        const contractAddress = this._getContractAddress(
+            artifacts.EtherTokenArtifact, this._contractAddressIfExists,
+        );
+        return contractAddress;
     }
     private _invalidateContractInstance(): void {
         delete this._etherTokenContractIfExists;
@@ -81,7 +85,7 @@ export class EtherTokenWrapper extends ContractWrapper {
         const contractInstance = await this._instantiateContractIfExistsAsync<EtherTokenContract>(
             artifacts.EtherTokenArtifact, this._contractAddressIfExists,
         );
-        this._etherTokenContractIfExists = contractInstance as EtherTokenContract;
+        this._etherTokenContractIfExists = contractInstance;
         return this._etherTokenContractIfExists;
     }
 }
diff --git a/packages/0x.js/src/contract_wrappers/exchange_wrapper.ts b/packages/0x.js/src/contract_wrappers/exchange_wrapper.ts
index 7c33dc6ec..91b41c4a4 100644
--- a/packages/0x.js/src/contract_wrappers/exchange_wrapper.ts
+++ b/packages/0x.js/src/contract_wrappers/exchange_wrapper.ts
@@ -1,45 +1,46 @@
+import {schemas} from '@0xproject/json-schemas';
+import BigNumber from 'bignumber.js';
 import * as _ from 'lodash';
 import * as Web3 from 'web3';
-import BigNumber from 'bignumber.js';
-import {schemas} from '@0xproject/json-schemas';
-import {Web3Wrapper} from '../web3_wrapper';
+
+import {artifacts} from '../artifacts';
 import {
+    BlockParamLiteral,
+    DecodedLogArgs,
     ECSignature,
+    EventCallback,
     ExchangeContract,
     ExchangeContractErrCodes,
     ExchangeContractErrs,
-    ZeroExError,
-    OrderValues,
-    OrderAddresses,
-    Order,
-    SignedOrder,
+    ExchangeContractEventArgs,
     ExchangeEvents,
-    SubscriptionOpts,
     IndexedFilterValues,
-    OrderCancellationRequest,
-    OrderFillRequest,
+    LogCancelContractEventArgs,
     LogErrorContractEventArgs,
     LogFillContractEventArgs,
-    LogCancelContractEventArgs,
     LogWithDecodedArgs,
     MethodOpts,
-    ValidateOrderFillableOpts,
+    Order,
+    OrderAddresses,
+    OrderCancellationRequest,
+    OrderFillRequest,
     OrderTransactionOpts,
+    OrderValues,
     RawLog,
-    EventCallback,
-    ExchangeContractEventArgs,
-    DecodedLogArgs,
-    BlockParamLiteral,
+    SignedOrder,
+    SubscriptionOpts,
+    ValidateOrderFillableOpts,
 } from '../types';
+import {AbiDecoder} from '../utils/abi_decoder';
 import {assert} from '../utils/assert';
-import {utils} from '../utils/utils';
+import {decorators} from '../utils/decorators';
+import {ExchangeTransferSimulator} from '../utils/exchange_transfer_simulator';
 import {OrderValidationUtils} from '../utils/order_validation_utils';
+import {utils} from '../utils/utils';
+import {Web3Wrapper} from '../web3_wrapper';
+
 import {ContractWrapper} from './contract_wrapper';
 import {TokenWrapper} from './token_wrapper';
-import {decorators} from '../utils/decorators';
-import {AbiDecoder} from '../utils/abi_decoder';
-import {ExchangeTransferSimulator} from '../utils/exchange_transfer_simulator';
-import {artifacts} from '../artifacts';
 
 const SHOULD_VALIDATE_BY_DEFAULT = true;
 
@@ -64,6 +65,7 @@ export class ExchangeWrapper extends ContractWrapper {
         [ExchangeContractErrCodes.ERROR_FILL_BALANCE_ALLOWANCE]: ExchangeContractErrs.FillBalanceAllowanceError,
     };
     private _contractAddressIfExists?: string;
+    private _zrxContractAddressIfExists?: string;
     private static _getOrderAddressesAndValues(order: Order): [OrderAddresses, OrderValues] {
         const orderAddresses: OrderAddresses = [
             order.maker,
@@ -178,7 +180,7 @@ export class ExchangeWrapper extends ContractWrapper {
             SHOULD_VALIDATE_BY_DEFAULT :
             orderTransactionOpts.shouldValidate;
         if (shouldValidate) {
-            const zrxTokenAddress = await this.getZRXTokenAddressAsync();
+            const zrxTokenAddress = this.getZRXTokenAddress();
             const exchangeTradeEmulator = new ExchangeTransferSimulator(this._tokenWrapper, BlockParamLiteral.Latest);
             await this._orderValidationUtils.validateFillOrderThrowIfInvalidAsync(
                 exchangeTradeEmulator, signedOrder, fillTakerTokenAmount, takerAddress, zrxTokenAddress);
@@ -250,7 +252,7 @@ export class ExchangeWrapper extends ContractWrapper {
             SHOULD_VALIDATE_BY_DEFAULT :
             orderTransactionOpts.shouldValidate;
         if (shouldValidate) {
-            const zrxTokenAddress = await this.getZRXTokenAddressAsync();
+            const zrxTokenAddress = this.getZRXTokenAddress();
             const exchangeTradeEmulator = new ExchangeTransferSimulator(this._tokenWrapper, BlockParamLiteral.Latest);
             for (const signedOrder of signedOrders) {
                 await this._orderValidationUtils.validateFillOrderThrowIfInvalidAsync(
@@ -340,7 +342,7 @@ export class ExchangeWrapper extends ContractWrapper {
             SHOULD_VALIDATE_BY_DEFAULT :
             orderTransactionOpts.shouldValidate;
         if (shouldValidate) {
-            const zrxTokenAddress = await this.getZRXTokenAddressAsync();
+            const zrxTokenAddress = this.getZRXTokenAddress();
             const exchangeTradeEmulator = new ExchangeTransferSimulator(this._tokenWrapper, BlockParamLiteral.Latest);
             for (const orderFillRequest of orderFillRequests) {
                 await this._orderValidationUtils.validateFillOrderThrowIfInvalidAsync(
@@ -420,7 +422,7 @@ export class ExchangeWrapper extends ContractWrapper {
             SHOULD_VALIDATE_BY_DEFAULT :
             orderTransactionOpts.shouldValidate;
         if (shouldValidate) {
-            const zrxTokenAddress = await this.getZRXTokenAddressAsync();
+            const zrxTokenAddress = this.getZRXTokenAddress();
             const exchangeTradeEmulator = new ExchangeTransferSimulator(this._tokenWrapper, BlockParamLiteral.Latest);
             await this._orderValidationUtils.validateFillOrKillOrderThrowIfInvalidAsync(
                 exchangeTradeEmulator, signedOrder, fillTakerTokenAmount, takerAddress, zrxTokenAddress);
@@ -484,7 +486,7 @@ export class ExchangeWrapper extends ContractWrapper {
             SHOULD_VALIDATE_BY_DEFAULT :
             orderTransactionOpts.shouldValidate;
         if (shouldValidate) {
-            const zrxTokenAddress = await this.getZRXTokenAddressAsync();
+            const zrxTokenAddress = this.getZRXTokenAddress();
             const exchangeTradeEmulator = new ExchangeTransferSimulator(this._tokenWrapper, BlockParamLiteral.Latest);
             for (const orderFillRequest of orderFillRequests) {
                 await this._orderValidationUtils.validateFillOrKillOrderThrowIfInvalidAsync(
@@ -557,7 +559,7 @@ export class ExchangeWrapper extends ContractWrapper {
         if (shouldValidate) {
             const orderHash = utils.getOrderHashHex(order);
             const unavailableTakerTokenAmount = await this.getUnavailableTakerAmountAsync(orderHash);
-            await this._orderValidationUtils.validateCancelOrderThrowIfInvalidAsync(
+            OrderValidationUtils.validateCancelOrderThrowIfInvalid(
                 order, cancelTakerTokenAmount, unavailableTakerTokenAmount);
         }
 
@@ -611,7 +613,7 @@ export class ExchangeWrapper extends ContractWrapper {
             for (const orderCancellationRequest of orderCancellationRequests) {
                 const orderHash = utils.getOrderHashHex(orderCancellationRequest.order);
                 const unavailableTakerTokenAmount = await this.getUnavailableTakerAmountAsync(orderHash);
-                await this._orderValidationUtils.validateCancelOrderThrowIfInvalidAsync(
+                OrderValidationUtils.validateCancelOrderThrowIfInvalid(
                     orderCancellationRequest.order, orderCancellationRequest.takerTokenCancelAmount,
                     unavailableTakerTokenAmount,
                 );
@@ -658,13 +660,13 @@ export class ExchangeWrapper extends ContractWrapper {
      * @param   callback            Callback that gets called when a log is added/removed
      * @return Subscription token used later to unsubscribe
      */
-    public async subscribeAsync<ArgsType extends ExchangeContractEventArgs>(
+    public subscribe<ArgsType extends ExchangeContractEventArgs>(
         eventName: ExchangeEvents, indexFilterValues: IndexedFilterValues,
-        callback: EventCallback<ArgsType>): Promise<string> {
+        callback: EventCallback<ArgsType>): string {
         assert.doesBelongToStringEnum('eventName', eventName, ExchangeEvents);
         assert.doesConformToSchema('indexFilterValues', indexFilterValues, schemas.indexFilterValuesSchema);
         assert.isFunction('callback', callback);
-        const exchangeContractAddress = await this.getContractAddressAsync();
+        const exchangeContractAddress = this.getContractAddress();
         const subscriptionToken = this._subscribe<ArgsType>(
             exchangeContractAddress, eventName, indexFilterValues, artifacts.ExchangeArtifact.abi, callback,
         );
@@ -691,7 +693,7 @@ export class ExchangeWrapper extends ContractWrapper {
         assert.doesBelongToStringEnum('eventName', eventName, ExchangeEvents);
         assert.doesConformToSchema('subscriptionOpts', subscriptionOpts, schemas.subscriptionOptsSchema);
         assert.doesConformToSchema('indexFilterValues', indexFilterValues, schemas.indexFilterValuesSchema);
-        const exchangeContractAddress = await this.getContractAddressAsync();
+        const exchangeContractAddress = this.getContractAddress();
         const logs = await this._getLogsAsync<ArgsType>(
             exchangeContractAddress, eventName, subscriptionOpts, indexFilterValues, artifacts.ExchangeArtifact.abi,
         );
@@ -702,10 +704,9 @@ export class ExchangeWrapper extends ContractWrapper {
      * that the user-passed web3 provider is connected to.
      * @returns The Ethereum address of the Exchange contract being used.
      */
-    public async getContractAddressAsync(): Promise<string> {
-        const exchangeInstance = await this._getExchangeContractAsync();
-        const exchangeAddress = exchangeInstance.address;
-        return exchangeAddress;
+    public getContractAddress(): string {
+        const contractAddress = this._getContractAddress(artifacts.ExchangeArtifact, this._contractAddressIfExists);
+        return contractAddress;
     }
     /**
      * Checks if order is still fillable and throws an error otherwise. Useful for orderbook
@@ -720,7 +721,7 @@ export class ExchangeWrapper extends ContractWrapper {
         signedOrder: SignedOrder, opts?: ValidateOrderFillableOpts,
     ): Promise<void> {
         assert.doesConformToSchema('signedOrder', signedOrder, schemas.signedOrderSchema);
-        const zrxTokenAddress = await this.getZRXTokenAddressAsync();
+        const zrxTokenAddress = this.getZRXTokenAddress();
         const expectedFillTakerTokenAmount = !_.isUndefined(opts) ? opts.expectedFillTakerTokenAmount : undefined;
         const exchangeTradeEmulator = new ExchangeTransferSimulator(this._tokenWrapper, BlockParamLiteral.Latest);
         await this._orderValidationUtils.validateOrderFillableOrThrowAsync(
@@ -741,7 +742,7 @@ export class ExchangeWrapper extends ContractWrapper {
         assert.doesConformToSchema('signedOrder', signedOrder, schemas.signedOrderSchema);
         assert.isValidBaseUnitAmount('fillTakerTokenAmount', fillTakerTokenAmount);
         await assert.isSenderAddressAsync('takerAddress', takerAddress, this._web3Wrapper);
-        const zrxTokenAddress = await this.getZRXTokenAddressAsync();
+        const zrxTokenAddress = this.getZRXTokenAddress();
         const exchangeTradeEmulator = new ExchangeTransferSimulator(this._tokenWrapper, BlockParamLiteral.Latest);
         await this._orderValidationUtils.validateFillOrderThrowIfInvalidAsync(
             exchangeTradeEmulator, signedOrder, fillTakerTokenAmount, takerAddress, zrxTokenAddress);
@@ -758,7 +759,7 @@ export class ExchangeWrapper extends ContractWrapper {
         assert.isValidBaseUnitAmount('cancelTakerTokenAmount', cancelTakerTokenAmount);
         const orderHash = utils.getOrderHashHex(order);
         const unavailableTakerTokenAmount = await this.getUnavailableTakerAmountAsync(orderHash);
-        await this._orderValidationUtils.validateCancelOrderThrowIfInvalidAsync(
+        OrderValidationUtils.validateCancelOrderThrowIfInvalid(
             order, cancelTakerTokenAmount, unavailableTakerTokenAmount);
     }
     /**
@@ -775,7 +776,7 @@ export class ExchangeWrapper extends ContractWrapper {
         assert.doesConformToSchema('signedOrder', signedOrder, schemas.signedOrderSchema);
         assert.isValidBaseUnitAmount('fillTakerTokenAmount', fillTakerTokenAmount);
         await assert.isSenderAddressAsync('takerAddress', takerAddress, this._web3Wrapper);
-        const zrxTokenAddress = await this.getZRXTokenAddressAsync();
+        const zrxTokenAddress = this.getZRXTokenAddress();
         const exchangeTradeEmulator = new ExchangeTransferSimulator(this._tokenWrapper, BlockParamLiteral.Latest);
         await this._orderValidationUtils.validateFillOrKillOrderThrowIfInvalidAsync(
             exchangeTradeEmulator, signedOrder, fillTakerTokenAmount, takerAddress, zrxTokenAddress);
@@ -820,12 +821,13 @@ export class ExchangeWrapper extends ContractWrapper {
      * Returns the ZRX token address used by the exchange contract.
      * @return Address of ZRX token
      */
-    public async getZRXTokenAddressAsync(): Promise<string> {
-        const exchangeInstance = await this._getExchangeContractAsync();
-        const ZRXtokenAddress = await exchangeInstance.ZRX_TOKEN_CONTRACT.callAsync();
-        return ZRXtokenAddress;
+    public getZRXTokenAddress(): string {
+        const contractAddress = this._getContractAddress(
+            artifacts.ZRXArtifact, this._zrxContractAddressIfExists,
+        );
+        return contractAddress;
     }
-    private async _invalidateContractInstancesAsync(): Promise<void> {
+    private _invalidateContractInstances(): void {
         this.unsubscribeAll();
         delete this._exchangeContractIfExists;
     }
@@ -859,7 +861,7 @@ export class ExchangeWrapper extends ContractWrapper {
         const contractInstance = await this._instantiateContractIfExistsAsync<ExchangeContract>(
             artifacts.ExchangeArtifact, this._contractAddressIfExists,
         );
-        this._exchangeContractIfExists = contractInstance as ExchangeContract;
+        this._exchangeContractIfExists = contractInstance;
         return this._exchangeContractIfExists;
     }
     private async _getTokenTransferProxyAddressAsync(): Promise<string> {
@@ -868,4 +870,4 @@ export class ExchangeWrapper extends ContractWrapper {
         const tokenTransferProxyAddressLowerCase = tokenTransferProxyAddress.toLowerCase();
         return tokenTransferProxyAddressLowerCase;
     }
-}
+} // tslint:disable:max-file-line-count
diff --git a/packages/0x.js/src/contract_wrappers/token_registry_wrapper.ts b/packages/0x.js/src/contract_wrappers/token_registry_wrapper.ts
index 2cc5a9aa0..35337fa35 100644
--- a/packages/0x.js/src/contract_wrappers/token_registry_wrapper.ts
+++ b/packages/0x.js/src/contract_wrappers/token_registry_wrapper.ts
@@ -1,10 +1,12 @@
 import * as _ from 'lodash';
-import {Web3Wrapper} from '../web3_wrapper';
+
+import {artifacts} from '../artifacts';
+import {Token, TokenMetadata, TokenRegistryContract, ZeroExError} from '../types';
 import {assert} from '../utils/assert';
-import {Token, TokenRegistryContract, TokenMetadata} from '../types';
 import {constants} from '../utils/constants';
+import {Web3Wrapper} from '../web3_wrapper';
+
 import {ContractWrapper} from './contract_wrapper';
-import {artifacts} from '../artifacts';
 
 /**
  * This class includes all the functionality related to interacting with the 0x Token Registry smart contract.
@@ -12,6 +14,18 @@ import {artifacts} from '../artifacts';
 export class TokenRegistryWrapper extends ContractWrapper {
     private _tokenRegistryContractIfExists?: TokenRegistryContract;
     private _contractAddressIfExists?: string;
+    private static _createTokenFromMetadata(metadata: TokenMetadata): Token|undefined {
+        if (metadata[0] === constants.NULL_ADDRESS) {
+            return undefined;
+        }
+        const token = {
+            address: metadata[0],
+            name: metadata[1],
+            symbol: metadata[2],
+            decimals: metadata[3].toNumber(),
+        };
+        return token;
+    }
     constructor(web3Wrapper: Web3Wrapper, contractAddressIfExists?: string) {
         super(web3Wrapper);
         this._contractAddressIfExists = contractAddressIfExists;
@@ -26,7 +40,7 @@ export class TokenRegistryWrapper extends ContractWrapper {
         const addresses = await this.getTokenAddressesAsync();
         const tokenPromises: Array<Promise<Token|undefined>> = _.map(
             addresses,
-            (address: string) => (this.getTokenIfExistsAsync(address)),
+            async (address: string) => this.getTokenIfExistsAsync(address),
         );
         const tokens = await Promise.all(tokenPromises);
         return tokens as Token[];
@@ -49,7 +63,7 @@ export class TokenRegistryWrapper extends ContractWrapper {
 
         const tokenRegistryContract = await this._getTokenRegistryContractAsync();
         const metadata = await tokenRegistryContract.getTokenMetaData.callAsync(address);
-        const token = this._createTokenFromMetadata(metadata);
+        const token = TokenRegistryWrapper._createTokenFromMetadata(metadata);
         return token;
     }
     public async getTokenAddressBySymbolIfExistsAsync(symbol: string): Promise<string|undefined> {
@@ -74,14 +88,14 @@ export class TokenRegistryWrapper extends ContractWrapper {
         assert.isString('symbol', symbol);
         const tokenRegistryContract = await this._getTokenRegistryContractAsync();
         const metadata = await tokenRegistryContract.getTokenBySymbol.callAsync(symbol);
-        const token = this._createTokenFromMetadata(metadata);
+        const token = TokenRegistryWrapper._createTokenFromMetadata(metadata);
         return token;
     }
     public async getTokenByNameIfExistsAsync(name: string): Promise<Token|undefined> {
         assert.isString('name', name);
         const tokenRegistryContract = await this._getTokenRegistryContractAsync();
         const metadata = await tokenRegistryContract.getTokenByName.callAsync(name);
-        const token = this._createTokenFromMetadata(metadata);
+        const token = TokenRegistryWrapper._createTokenFromMetadata(metadata);
         return token;
     }
     /**
@@ -89,22 +103,11 @@ export class TokenRegistryWrapper extends ContractWrapper {
      * that the user-passed web3 provider is connected to.
      * @returns The Ethereum address of the TokenRegistry contract being used.
      */
-    public async getContractAddressAsync(): Promise<string> {
-        const tokenRegistryInstance = await this._getTokenRegistryContractAsync();
-        const tokenRegistryAddress = tokenRegistryInstance.address;
-        return tokenRegistryAddress;
-    }
-    private _createTokenFromMetadata(metadata: TokenMetadata): Token|undefined {
-        if (metadata[0] === constants.NULL_ADDRESS) {
-            return undefined;
-        }
-        const token = {
-            address: metadata[0],
-            name: metadata[1],
-            symbol: metadata[2],
-            decimals: metadata[3].toNumber(),
-        };
-        return token;
+    public getContractAddress(): string {
+        const contractAddress = this._getContractAddress(
+            artifacts.TokenRegistryArtifact, this._contractAddressIfExists,
+        );
+        return contractAddress;
     }
     private _invalidateContractInstance(): void {
         delete this._tokenRegistryContractIfExists;
@@ -116,7 +119,7 @@ export class TokenRegistryWrapper extends ContractWrapper {
         const contractInstance = await this._instantiateContractIfExistsAsync<TokenRegistryContract>(
             artifacts.TokenRegistryArtifact, this._contractAddressIfExists,
         );
-        this._tokenRegistryContractIfExists = contractInstance as TokenRegistryContract;
+        this._tokenRegistryContractIfExists = contractInstance;
         return this._tokenRegistryContractIfExists;
     }
 }
diff --git a/packages/0x.js/src/contract_wrappers/token_transfer_proxy_wrapper.ts b/packages/0x.js/src/contract_wrappers/token_transfer_proxy_wrapper.ts
index f81845af9..c3df7d3eb 100644
--- a/packages/0x.js/src/contract_wrappers/token_transfer_proxy_wrapper.ts
+++ b/packages/0x.js/src/contract_wrappers/token_transfer_proxy_wrapper.ts
@@ -1,18 +1,20 @@
 import * as _ from 'lodash';
+
+import {artifacts} from '../artifacts';
+import {TokenTransferProxyContract, ZeroExError} from '../types';
 import {Web3Wrapper} from '../web3_wrapper';
+
 import {ContractWrapper} from './contract_wrapper';
-import {artifacts} from '../artifacts';
-import {TokenTransferProxyContract} from '../types';
 
 /**
  * This class includes the functionality related to interacting with the TokenTransferProxy contract.
  */
 export class TokenTransferProxyWrapper extends ContractWrapper {
     private _tokenTransferProxyContractIfExists?: TokenTransferProxyContract;
-    private _tokenTransferProxyContractAddressFetcher: () => Promise<string>;
-    constructor(web3Wrapper: Web3Wrapper, tokenTransferProxyContractAddressFetcher: () => Promise<string>) {
+    private _contractAddressIfExists?: string;
+    constructor(web3Wrapper: Web3Wrapper, contractAddressIfExists?: string) {
         super(web3Wrapper);
-        this._tokenTransferProxyContractAddressFetcher = tokenTransferProxyContractAddressFetcher;
+        this._contractAddressIfExists = contractAddressIfExists;
     }
     /**
      * Check if the Exchange contract address is authorized by the TokenTransferProxy contract.
@@ -38,10 +40,11 @@ export class TokenTransferProxyWrapper extends ContractWrapper {
      * that the user-passed web3 provider is connected to.
      * @returns The Ethereum address of the TokenTransferProxy contract being used.
      */
-    public async getContractAddressAsync(): Promise<string> {
-        const proxyInstance = await this._getTokenTransferProxyContractAsync();
-        const proxyAddress = proxyInstance.address;
-        return proxyAddress;
+    public getContractAddress(): string {
+        const contractAddress = this._getContractAddress(
+            artifacts.TokenTransferProxyArtifact, this._contractAddressIfExists,
+        );
+        return contractAddress;
     }
     private _invalidateContractInstance(): void {
         delete this._tokenTransferProxyContractIfExists;
@@ -50,11 +53,10 @@ export class TokenTransferProxyWrapper extends ContractWrapper {
         if (!_.isUndefined(this._tokenTransferProxyContractIfExists)) {
             return this._tokenTransferProxyContractIfExists;
         }
-        const contractAddress = await this._tokenTransferProxyContractAddressFetcher();
         const contractInstance = await this._instantiateContractIfExistsAsync<TokenTransferProxyContract>(
-            artifacts.TokenTransferProxyArtifact, contractAddress,
+            artifacts.TokenTransferProxyArtifact, this._contractAddressIfExists,
         );
-        this._tokenTransferProxyContractIfExists = contractInstance as TokenTransferProxyContract;
+        this._tokenTransferProxyContractIfExists = contractInstance;
         return this._tokenTransferProxyContractIfExists;
     }
 }
diff --git a/packages/0x.js/src/contract_wrappers/token_wrapper.ts b/packages/0x.js/src/contract_wrappers/token_wrapper.ts
index 4b89d3cfc..5c6cfeaed 100644
--- a/packages/0x.js/src/contract_wrappers/token_wrapper.ts
+++ b/packages/0x.js/src/contract_wrappers/token_wrapper.ts
@@ -1,23 +1,26 @@
-import * as _ from 'lodash';
-import BigNumber from 'bignumber.js';
 import {schemas} from '@0xproject/json-schemas';
-import {Web3Wrapper} from '../web3_wrapper';
-import {assert} from '../utils/assert';
-import {constants} from '../utils/constants';
-import {ContractWrapper} from './contract_wrapper';
-import {AbiDecoder} from '../utils/abi_decoder';
+import BigNumber from 'bignumber.js';
+import * as _ from 'lodash';
+
 import {artifacts} from '../artifacts';
 import {
-    TokenContract,
-    ZeroExError,
-    TokenEvents,
+    EventCallback,
     IndexedFilterValues,
-    SubscriptionOpts,
-    MethodOpts,
     LogWithDecodedArgs,
-    EventCallback,
+    MethodOpts,
+    SubscriptionOpts,
+    TokenContract,
     TokenContractEventArgs,
+    TokenEvents,
+    ZeroExError,
 } from '../types';
+import {AbiDecoder} from '../utils/abi_decoder';
+import {assert} from '../utils/assert';
+import {constants} from '../utils/constants';
+import {Web3Wrapper} from '../web3_wrapper';
+
+import {ContractWrapper} from './contract_wrapper';
+import {TokenTransferProxyWrapper} from './token_transfer_proxy_wrapper';
 
 const ALLOWANCE_TO_ZERO_GAS_AMOUNT = 47275;
 
@@ -29,12 +32,12 @@ const ALLOWANCE_TO_ZERO_GAS_AMOUNT = 47275;
 export class TokenWrapper extends ContractWrapper {
     public UNLIMITED_ALLOWANCE_IN_BASE_UNITS = constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS;
     private _tokenContractsByAddress: {[address: string]: TokenContract};
-    private _tokenTransferProxyContractAddressFetcher: () => Promise<string>;
+    private _tokenTransferProxyWrapper: TokenTransferProxyWrapper;
     constructor(web3Wrapper: Web3Wrapper, abiDecoder: AbiDecoder,
-                tokenTransferProxyContractAddressFetcher: () => Promise<string>) {
+                tokenTransferProxyWrapper: TokenTransferProxyWrapper) {
         super(web3Wrapper, abiDecoder);
         this._tokenContractsByAddress = {};
-        this._tokenTransferProxyContractAddressFetcher = tokenTransferProxyContractAddressFetcher;
+        this._tokenTransferProxyWrapper = tokenTransferProxyWrapper;
     }
     /**
      * Retrieves an owner's ERC20 token balance.
@@ -76,8 +79,8 @@ export class TokenWrapper extends ContractWrapper {
         // Hack: for some reason default estimated gas amount causes `base fee exceeds gas limit` exception
         // on testrpc. Probably related to https://github.com/ethereumjs/testrpc/issues/294
         // TODO: Debug issue in testrpc and submit a PR, then remove this hack
-        const networkIdIfExists = await this._web3Wrapper.getNetworkIdIfExistsAsync();
-        const gas = networkIdIfExists === constants.TESTRPC_NETWORK_ID ? ALLOWANCE_TO_ZERO_GAS_AMOUNT : undefined;
+        const networkId = this._web3Wrapper.getNetworkId();
+        const gas = networkId === constants.TESTRPC_NETWORK_ID ? ALLOWANCE_TO_ZERO_GAS_AMOUNT : undefined;
         const txHash = await tokenContract.approve.sendTransactionAsync(spenderAddress, amountInBaseUnits, {
             from: ownerAddress,
             gas,
@@ -133,7 +136,7 @@ export class TokenWrapper extends ContractWrapper {
         assert.isETHAddressHex('ownerAddress', ownerAddress);
         assert.isETHAddressHex('tokenAddress', tokenAddress);
 
-        const proxyAddress = await this._getTokenTransferProxyAddressAsync();
+        const proxyAddress = this._tokenTransferProxyWrapper.getContractAddress();
         const allowanceInBaseUnits = await this.getAllowanceAsync(tokenAddress, ownerAddress, proxyAddress, methodOpts);
         return allowanceInBaseUnits;
     }
@@ -152,7 +155,7 @@ export class TokenWrapper extends ContractWrapper {
         assert.isETHAddressHex('tokenAddress', tokenAddress);
         assert.isValidBaseUnitAmount('amountInBaseUnits', amountInBaseUnits);
 
-        const proxyAddress = await this._getTokenTransferProxyAddressAsync();
+        const proxyAddress = this._tokenTransferProxyWrapper.getContractAddress();
         const txHash = await this.setAllowanceAsync(tokenAddress, ownerAddress, proxyAddress, amountInBaseUnits);
         return txHash;
     }
@@ -290,7 +293,7 @@ export class TokenWrapper extends ContractWrapper {
         );
         return logs;
     }
-    private _invalidateContractInstancesAsync(): void {
+    private _invalidateContractInstances(): void {
         this.unsubscribeAll();
         this._tokenContractsByAddress = {};
     }
@@ -302,12 +305,8 @@ export class TokenWrapper extends ContractWrapper {
         const contractInstance = await this._instantiateContractIfExistsAsync<TokenContract>(
             artifacts.TokenArtifact, tokenAddress,
         );
-        tokenContract = contractInstance as TokenContract;
+        tokenContract = contractInstance;
         this._tokenContractsByAddress[tokenAddress] = tokenContract;
         return tokenContract;
     }
-    private async _getTokenTransferProxyAddressAsync(): Promise<string> {
-        const tokenTransferProxyContractAddress = await this._tokenTransferProxyContractAddressFetcher();
-        return tokenTransferProxyContractAddress;
-    }
 }
diff --git a/packages/0x.js/src/order_watcher/event_watcher.ts b/packages/0x.js/src/order_watcher/event_watcher.ts
index ecbab0cd5..831f19da5 100644
--- a/packages/0x.js/src/order_watcher/event_watcher.ts
+++ b/packages/0x.js/src/order_watcher/event_watcher.ts
@@ -1,6 +1,6 @@
-import * as Web3 from 'web3';
 import * as _ from 'lodash';
-import {Web3Wrapper} from '../web3_wrapper';
+import * as Web3 from 'web3';
+
 import {
     BlockParamLiteral,
     EventCallback,
@@ -8,9 +8,10 @@ import {
     ZeroExError,
 } from '../types';
 import {AbiDecoder} from '../utils/abi_decoder';
-import {intervalUtils} from '../utils/interval_utils';
 import {assert} from '../utils/assert';
+import {intervalUtils} from '../utils/interval_utils';
 import {utils} from '../utils/utils';
+import {Web3Wrapper} from '../web3_wrapper';
 
 const DEFAULT_EVENT_POLLING_INTERVAL_MS = 200;
 
diff --git a/packages/0x.js/src/order_watcher/expiration_watcher.ts b/packages/0x.js/src/order_watcher/expiration_watcher.ts
index 717edaad7..9a1bb1ca4 100644
--- a/packages/0x.js/src/order_watcher/expiration_watcher.ts
+++ b/packages/0x.js/src/order_watcher/expiration_watcher.ts
@@ -1,10 +1,11 @@
-import * as _ from 'lodash';
 import {BigNumber} from 'bignumber.js';
 import {RBTree} from 'bintrees';
-import {utils} from '../utils/utils';
-import {intervalUtils} from '../utils/interval_utils';
-import {SignedOrder, ZeroExError} from '../types';
+import * as _ from 'lodash';
+
 import {ZeroEx} from '../0x';
+import {SignedOrder, ZeroExError} from '../types';
+import {intervalUtils} from '../utils/interval_utils';
+import {utils} from '../utils/utils';
 
 const DEFAULT_EXPIRATION_MARGIN_MS = 0;
 const DEFAULT_ORDER_EXPIRATION_CHECKING_INTERVAL_MS = 50;
@@ -29,12 +30,12 @@ export class ExpirationWatcher {
         const comparator = (lhs: string, rhs: string) => scoreFunction(lhs) - scoreFunction(rhs);
         this.orderHashByExpirationRBTree = new RBTree(comparator);
     }
-    public subscribe(callbackAsync: (orderHash: string) => Promise<void>): void {
+    public subscribe(callback: (orderHash: string) => void): void {
         if (!_.isUndefined(this.orderExpirationCheckingIntervalIdIfExists)) {
             throw new Error(ZeroExError.SubscriptionAlreadyPresent);
         }
         this.orderExpirationCheckingIntervalIdIfExists = intervalUtils.setAsyncExcludingInterval(
-            this.pruneExpiredOrdersAsync.bind(this, callbackAsync), this.orderExpirationCheckingIntervalMs,
+            this.pruneExpiredOrders.bind(this, callback), this.orderExpirationCheckingIntervalMs,
         );
     }
     public unsubscribe(): void {
@@ -52,7 +53,7 @@ export class ExpirationWatcher {
         this.orderHashByExpirationRBTree.remove(orderHash);
         delete this.expiration[orderHash];
     }
-    private async pruneExpiredOrdersAsync(callbackAsync: (orderHash: string) => Promise<void>): Promise<void> {
+    private pruneExpiredOrders(callback: (orderHash: string) => void): void {
         const currentUnixTimestampMs = utils.getCurrentUnixTimestampMs();
         while (true) {
             const hasTrakedOrders = this.orderHashByExpirationRBTree.size === 0;
@@ -70,7 +71,7 @@ export class ExpirationWatcher {
             const orderHash = this.orderHashByExpirationRBTree.min();
             this.orderHashByExpirationRBTree.remove(orderHash);
             delete this.expiration[orderHash];
-            await callbackAsync(orderHash);
+            callback(orderHash);
         }
     }
 }
diff --git a/packages/0x.js/src/order_watcher/order_state_watcher.ts b/packages/0x.js/src/order_watcher/order_state_watcher.ts
index d02e31160..8c21c1678 100644
--- a/packages/0x.js/src/order_watcher/order_state_watcher.ts
+++ b/packages/0x.js/src/order_watcher/order_state_watcher.ts
@@ -1,42 +1,44 @@
-import * as _ from 'lodash';
 import {schemas} from '@0xproject/json-schemas';
+import * as _ from 'lodash';
+
 import {ZeroEx} from '../0x';
-import {EventWatcher} from './event_watcher';
-import {assert} from '../utils/assert';
-import {utils} from '../utils/utils';
 import {artifacts} from '../artifacts';
-import {AbiDecoder} from '../utils/abi_decoder';
-import {intervalUtils} from '../utils/interval_utils';
-import {OrderStateUtils} from '../utils/order_state_utils';
+import {ExchangeWrapper} from '../contract_wrappers/exchange_wrapper';
+import {TokenWrapper} from '../contract_wrappers/token_wrapper';
+import {BalanceAndProxyAllowanceLazyStore} from '../stores/balance_proxy_allowance_lazy_store';
+import {OrderFilledCancelledLazyStore} from '../stores/order_filled_cancelled_lazy_store';
 import {
-    LogEvent,
-    OrderState,
-    SignedOrder,
-    Web3Provider,
+    ApprovalContractEventArgs,
     BlockParamLiteral,
-    LogWithDecodedArgs,
     ContractEventArgs,
+    ExchangeContractErrs,
+    ExchangeEvents,
+    LogCancelContractEventArgs,
+    LogEvent,
+    LogFillContractEventArgs,
+    LogWithDecodedArgs,
     OnOrderStateChangeCallback,
+    OrderState,
     OrderStateWatcherConfig,
-    ApprovalContractEventArgs,
-    TransferContractEventArgs,
-    LogFillContractEventArgs,
-    LogCancelContractEventArgs,
-    ExchangeEvents,
+    SignedOrder,
     TokenEvents,
+    TransferContractEventArgs,
+    Web3Provider,
     ZeroExError,
-    ExchangeContractErrs,
 } from '../types';
+import {AbiDecoder} from '../utils/abi_decoder';
+import {assert} from '../utils/assert';
+import {intervalUtils} from '../utils/interval_utils';
+import {OrderStateUtils} from '../utils/order_state_utils';
+import {utils} from '../utils/utils';
 import {Web3Wrapper} from '../web3_wrapper';
-import {TokenWrapper} from '../contract_wrappers/token_wrapper';
-import {ExchangeWrapper} from '../contract_wrappers/exchange_wrapper';
-import {OrderFilledCancelledLazyStore} from '../stores/order_filled_cancelled_lazy_store';
-import {BalanceAndProxyAllowanceLazyStore} from '../stores/balance_proxy_allowance_lazy_store';
+
+import {EventWatcher} from './event_watcher';
 import {ExpirationWatcher} from './expiration_watcher';
 
 interface DependentOrderHashes {
     [makerAddress: string]: {
-        [makerToken: string]: Set<string>,
+        [makerToken: string]: Set<string>;
     };
 }
 
@@ -96,12 +98,12 @@ export class OrderStateWatcher {
      * signature is verified.
      * @param   signedOrder     The order you wish to start watching.
      */
-    public async addOrderAsync(signedOrder: SignedOrder): Promise<void> {
+    public addOrder(signedOrder: SignedOrder): void {
         assert.doesConformToSchema('signedOrder', signedOrder, schemas.signedOrderSchema);
         const orderHash = ZeroEx.getOrderHashHex(signedOrder);
         assert.isValidSignature(orderHash, signedOrder.ecSignature, signedOrder.maker);
         this._orderByOrderHash[orderHash] = signedOrder;
-        await this.addToDependentOrderHashesAsync(signedOrder, orderHash);
+        this.addToDependentOrderHashes(signedOrder, orderHash);
         const expirationUnixTimestampMs = signedOrder.expirationUnixTimestampSec.times(1000);
         this._expirationWatcher.addOrder(orderHash, expirationUnixTimestampMs);
     }
@@ -109,7 +111,7 @@ export class OrderStateWatcher {
      * Removes an order from the orderStateWatcher
      * @param   orderHash     The orderHash of the order you wish to stop watching.
      */
-    public async removeOrderAsync(orderHash: string): Promise<void> {
+    public removeOrder(orderHash: string): void {
         assert.doesConformToSchema('orderHash', orderHash, schemas.orderHashSchema);
         const signedOrder = this._orderByOrderHash[orderHash];
         if (_.isUndefined(signedOrder)) {
@@ -118,7 +120,7 @@ export class OrderStateWatcher {
         delete this._orderByOrderHash[orderHash];
         delete this._orderStateByOrderHashCache[orderHash];
         const exchange = (this._orderFilledCancelledLazyStore as any).exchange as ExchangeWrapper;
-        const zrxTokenAddress = await exchange.getZRXTokenAddressAsync();
+        const zrxTokenAddress = exchange.getZRXTokenAddress();
         this.removeFromDependentOrderHashes(signedOrder.maker, zrxTokenAddress, orderHash);
         this.removeFromDependentOrderHashes(signedOrder.maker, signedOrder.makerTokenAddress, orderHash);
         this._expirationWatcher.removeOrder(orderHash);
@@ -136,7 +138,7 @@ export class OrderStateWatcher {
         }
         this._callbackIfExists = callback;
         this._eventWatcher.subscribe(this._onEventWatcherCallbackAsync.bind(this));
-        this._expirationWatcher.subscribe(this._onOrderExpiredAsync.bind(this));
+        this._expirationWatcher.subscribe(this._onOrderExpired.bind(this));
     }
     /**
      * Ends an orderStateWatcher subscription.
@@ -151,14 +153,14 @@ export class OrderStateWatcher {
         this._eventWatcher.unsubscribe();
         this._expirationWatcher.unsubscribe();
     }
-    private async _onOrderExpiredAsync(orderHash: string): Promise<void> {
+    private _onOrderExpired(orderHash: string): void {
         const orderState: OrderState = {
             isValid: false,
             orderHash,
             error: ExchangeContractErrs.OrderFillExpired,
         };
         if (!_.isUndefined(this._orderByOrderHash[orderHash])) {
-            await this.removeOrderAsync(orderHash);
+            this.removeOrder(orderHash);
             if (!_.isUndefined(this._callbackIfExists)) {
                 this._callbackIfExists(orderState);
             }
@@ -240,7 +242,7 @@ export class OrderStateWatcher {
     }
     private async _emitRevalidateOrdersAsync(orderHashes: string[]): Promise<void> {
         for (const orderHash of orderHashes) {
-            const signedOrder = this._orderByOrderHash[orderHash] as SignedOrder;
+            const signedOrder = this._orderByOrderHash[orderHash];
             // Most of these calls will never reach the network because the data is fetched from stores
             // and only updated when cache is invalidated
             const orderState = await this._orderStateUtils.getOrderStateAsync(signedOrder);
@@ -256,7 +258,7 @@ export class OrderStateWatcher {
             this._callbackIfExists(orderState);
         }
     }
-    private async addToDependentOrderHashesAsync(signedOrder: SignedOrder, orderHash: string): Promise<void> {
+    private addToDependentOrderHashes(signedOrder: SignedOrder, orderHash: string): void {
         if (_.isUndefined(this._dependentOrderHashes[signedOrder.maker])) {
             this._dependentOrderHashes[signedOrder.maker] = {};
         }
@@ -265,7 +267,7 @@ export class OrderStateWatcher {
         }
         this._dependentOrderHashes[signedOrder.maker][signedOrder.makerTokenAddress].add(orderHash);
         const exchange = (this._orderFilledCancelledLazyStore as any).exchange as ExchangeWrapper;
-        const zrxTokenAddress = await exchange.getZRXTokenAddressAsync();
+        const zrxTokenAddress = exchange.getZRXTokenAddress();
         if (_.isUndefined(this._dependentOrderHashes[signedOrder.maker][zrxTokenAddress])) {
             this._dependentOrderHashes[signedOrder.maker][zrxTokenAddress] = new Set();
         }
diff --git a/packages/0x.js/src/order_watcher/remaining_fillable_calculator.ts b/packages/0x.js/src/order_watcher/remaining_fillable_calculator.ts
index c77d4428c..e8601e678 100644
--- a/packages/0x.js/src/order_watcher/remaining_fillable_calculator.ts
+++ b/packages/0x.js/src/order_watcher/remaining_fillable_calculator.ts
@@ -1,6 +1,7 @@
-import {SignedOrder} from '../types';
 import {BigNumber} from 'bignumber.js';
 
+import {SignedOrder} from '../types';
+
 export class RemainingFillableCalculator {
     private signedOrder: SignedOrder;
     private isMakerTokenZRX: boolean;
diff --git a/packages/0x.js/src/schemas/zero_ex_config_schema.ts b/packages/0x.js/src/schemas/zero_ex_config_schema.ts
index 6d4b3ed27..121d81257 100644
--- a/packages/0x.js/src/schemas/zero_ex_config_schema.ts
+++ b/packages/0x.js/src/schemas/zero_ex_config_schema.ts
@@ -1,6 +1,10 @@
 export const zeroExConfigSchema = {
     id: '/ZeroExConfig',
     properties: {
+        networkId: {
+            type: 'number',
+            minimum: 0,
+        },
         gasPrice: {$ref: '/Number'},
         exchangeContractAddress: {$ref: '/Address'},
         tokenRegistryContractAddress: {$ref: '/Address'},
@@ -20,4 +24,5 @@ export const zeroExConfigSchema = {
         },
     },
     type: 'object',
+    required: ['networkId'],
 };
diff --git a/packages/0x.js/src/stores/balance_proxy_allowance_lazy_store.ts b/packages/0x.js/src/stores/balance_proxy_allowance_lazy_store.ts
index 7c94031c3..6225e9e72 100644
--- a/packages/0x.js/src/stores/balance_proxy_allowance_lazy_store.ts
+++ b/packages/0x.js/src/stores/balance_proxy_allowance_lazy_store.ts
@@ -1,6 +1,7 @@
+import {BigNumber} from 'bignumber.js';
 import * as _ from 'lodash';
 import * as Web3 from 'web3';
-import {BigNumber} from 'bignumber.js';
+
 import {TokenWrapper} from '../contract_wrappers/token_wrapper';
 import {BlockParamLiteral} from '../types';
 
@@ -12,13 +13,13 @@ export class BalanceAndProxyAllowanceLazyStore {
     private defaultBlock: BlockParamLiteral;
     private balance: {
         [tokenAddress: string]: {
-            [userAddress: string]: BigNumber,
-        },
+            [userAddress: string]: BigNumber;
+        };
     };
     private proxyAllowance: {
         [tokenAddress: string]: {
-            [userAddress: string]: BigNumber,
-        },
+            [userAddress: string]: BigNumber;
+        };
     };
     constructor(token: TokenWrapper, defaultBlock: BlockParamLiteral) {
         this.token = token;
diff --git a/packages/0x.js/src/stores/order_filled_cancelled_lazy_store.ts b/packages/0x.js/src/stores/order_filled_cancelled_lazy_store.ts
index 666d8363c..28b32f9e2 100644
--- a/packages/0x.js/src/stores/order_filled_cancelled_lazy_store.ts
+++ b/packages/0x.js/src/stores/order_filled_cancelled_lazy_store.ts
@@ -1,6 +1,7 @@
+import {BigNumber} from 'bignumber.js';
 import * as _ from 'lodash';
 import * as Web3 from 'web3';
-import {BigNumber} from 'bignumber.js';
+
 import {ExchangeWrapper} from '../contract_wrappers/exchange_wrapper';
 import {BlockParamLiteral} from '../types';
 
@@ -10,10 +11,10 @@ import {BlockParamLiteral} from '../types';
 export class OrderFilledCancelledLazyStore {
     private exchange: ExchangeWrapper;
     private filledTakerAmount: {
-        [orderHash: string]: BigNumber,
+        [orderHash: string]: BigNumber;
     };
     private cancelledTakerAmount: {
-        [orderHash: string]: BigNumber,
+        [orderHash: string]: BigNumber;
     };
     constructor(exchange: ExchangeWrapper) {
         this.exchange = exchange;
diff --git a/packages/0x.js/src/subproviders/empty_wallet_subprovider.ts b/packages/0x.js/src/subproviders/empty_wallet_subprovider.ts
index 2f260217c..2993bc801 100644
--- a/packages/0x.js/src/subproviders/empty_wallet_subprovider.ts
+++ b/packages/0x.js/src/subproviders/empty_wallet_subprovider.ts
@@ -6,6 +6,8 @@ import {JSONRPCPayload} from '../types';
  * Source: https://github.com/MetaMask/provider-engine/blob/master/subproviders/subprovider.js
  */
 export class EmptyWalletSubProvider {
+    // This method needs to be here to satisfy the interface but linter wants it to be static.
+    // tslint:disable-next-line:prefer-function-over-method
     public handleRequest(payload: JSONRPCPayload, next: () => void, end: (err: Error|null, result: any) => void) {
         switch (payload.method) {
             case 'eth_accounts':
@@ -18,6 +20,7 @@ export class EmptyWalletSubProvider {
         }
     }
     // Required to implement this method despite not needing it for this subprovider
+    // tslint:disable-next-line:prefer-function-over-method
     public setEngine(engine: any) {
         // noop
     }
diff --git a/packages/0x.js/src/types.ts b/packages/0x.js/src/types.ts
index 4d55046b4..af4f054f0 100644
--- a/packages/0x.js/src/types.ts
+++ b/packages/0x.js/src/types.ts
@@ -1,9 +1,13 @@
-import * as Web3 from 'web3';
 import BigNumber from 'bignumber.js';
+import * as Web3 from 'web3';
 
 export enum ZeroExError {
-    ContractDoesNotExist = 'CONTRACT_DOES_NOT_EXIST',
     ExchangeContractDoesNotExist = 'EXCHANGE_CONTRACT_DOES_NOT_EXIST',
+    ZRXContractDoesNotExist = 'ZRX_CONTRACT_DOES_NOT_EXIST',
+    EtherTokenContractDoesNotExist = 'ETHER_TOKEN_CONTRACT_DOES_NOT_EXIST',
+    TokenTransferProxyContractDoesNotExist = 'TOKEN_TRANSFER_PROXY_CONTRACT_DOES_NOT_EXIST',
+    TokenRegistryContractDoesNotExist = 'TOKEN_REGISTRY_CONTRACT_DOES_NOT_EXIST',
+    TokenContractDoesNotExist = 'TOKEN_CONTRACT_DOES_NOT_EXIST',
     UnhandledError = 'UNHANDLED_ERROR',
     UserHasNoAssociatedAddress = 'USER_HAS_NO_ASSOCIATED_ADDRESSES',
     InvalidSignature = 'INVALID_SIGNATURE',
@@ -410,17 +414,21 @@ export interface OrderStateWatcherConfig {
 }
 
 /*
+ * networkId: The id of the underlying ethereum network your provider is connected to. (1-mainnet, 42-kovan, 50-testrpc)
  * gasPrice: Gas price to use with every transaction
  * exchangeContractAddress: The address of an exchange contract to use
  * tokenRegistryContractAddress: The address of a token registry contract to use
  * etherTokenContractAddress: The address of an ether token contract to use
+ * tokenTransferProxyContractAddress: The address of the token transfer proxy contract to use
  * orderWatcherConfig: All the configs related to the orderWatcher
  */
 export interface ZeroExConfig {
-    gasPrice?: BigNumber; // Gas price to use with every transaction
+    networkId: number;
+    gasPrice?: BigNumber;
     exchangeContractAddress?: string;
     tokenRegistryContractAddress?: string;
     etherTokenContractAddress?: string;
+    tokenTransferProxyContractAddress?: string;
     orderWatcherConfig?: OrderStateWatcherConfig;
 }
 
@@ -441,11 +449,16 @@ export interface TransactionReceiptWithDecodedLogs extends TransactionReceipt {
     logs: Array<LogWithDecodedArgs<DecodedLogArgs>|Web3.LogEntry>;
 }
 
+export type ArtifactContractName = 'ZRX'|'TokenTransferProxy'|'TokenRegistry'|'Token'|'Exchange'|'EtherToken';
+
 export interface Artifact {
-    abi: any;
-    networks: {[networkId: number]: {
-        address: string;
-    }};
+    contract_name: ArtifactContractName;
+    abi: Web3.ContractAbi;
+    networks: {
+        [networkId: number]: {
+            address: string;
+        };
+    };
 }
 
 /*
@@ -527,4 +540,4 @@ export interface TransactionReceipt {
     gasUsed: number;
     contractAddress: string|null;
     logs: Web3.LogEntry[];
-}
+} // tslint:disable:max-file-line-count
diff --git a/packages/0x.js/src/utils/abi_decoder.ts b/packages/0x.js/src/utils/abi_decoder.ts
index df0fb2d6f..f26b057f0 100644
--- a/packages/0x.js/src/utils/abi_decoder.ts
+++ b/packages/0x.js/src/utils/abi_decoder.ts
@@ -1,12 +1,22 @@
-import * as Web3 from 'web3';
-import * as _ from 'lodash';
 import BigNumber from 'bignumber.js';
-import {AbiType, DecodedLogArgs, LogWithDecodedArgs, RawLog, SolidityTypes, ContractEventArgs} from '../types';
+import * as _ from 'lodash';
+import * as Web3 from 'web3';
 import * as SolidityCoder from 'web3/lib/solidity/coder';
 
+import {AbiType, ContractEventArgs, DecodedLogArgs, LogWithDecodedArgs, RawLog, SolidityTypes} from '../types';
+
 export class AbiDecoder {
     private savedABIs: Web3.AbiDefinition[] = [];
     private methodIds: {[signatureHash: string]: Web3.EventAbi} = {};
+    private static padZeros(address: string) {
+        let formatted = address;
+        if (_.startsWith(formatted, '0x')) {
+            formatted = formatted.slice(2);
+        }
+
+        formatted = _.padStart(formatted, 40, '0');
+        return `0x${formatted}`;
+    }
     constructor(abiArrays: Web3.AbiDefinition[][]) {
         _.map(abiArrays, this.addABI.bind(this));
     }
@@ -31,7 +41,7 @@ export class AbiDecoder {
             // Indexed parameters are stored in topics. Non-indexed ones in decodedData
             let value = param.indexed ? log.topics[topicsIndex++] : decodedData[dataIndex++];
             if (param.type === SolidityTypes.Address) {
-                value = this.padZeros(new BigNumber(value).toString(16));
+                value = AbiDecoder.padZeros(new BigNumber(value).toString(16));
             } else if (param.type === SolidityTypes.Uint256 ||
                        param.type === SolidityTypes.Uint8 ||
                        param.type === SolidityTypes.Uint) {
@@ -56,13 +66,4 @@ export class AbiDecoder {
         });
         this.savedABIs = this.savedABIs.concat(abiArray);
     }
-    private padZeros(address: string) {
-        let formatted = address;
-        if (_.startsWith(formatted, '0x')) {
-            formatted = formatted.slice(2);
-        }
-
-        formatted = _.padStart(formatted, 40, '0');
-        return `0x${formatted}`;
-    }
 }
diff --git a/packages/0x.js/src/utils/assert.ts b/packages/0x.js/src/utils/assert.ts
index 55912525c..3cff9d2cf 100644
--- a/packages/0x.js/src/utils/assert.ts
+++ b/packages/0x.js/src/utils/assert.ts
@@ -1,11 +1,12 @@
+import {assert as sharedAssert} from '@0xproject/assert';
+import {Schema, SchemaValidator} from '@0xproject/json-schemas';
+import BigNumber from 'bignumber.js';
 import * as _ from 'lodash';
 import * as Web3 from 'web3';
-import BigNumber from 'bignumber.js';
-import {SchemaValidator, Schema} from '@0xproject/json-schemas';
-import {assert as sharedAssert} from '@0xproject/assert';
-import {Web3Wrapper} from '../web3_wrapper';
-import {signatureUtils} from '../utils/signature_utils';
+
 import {ECSignature} from '../types';
+import {signatureUtils} from '../utils/signature_utils';
+import {Web3Wrapper} from '../web3_wrapper';
 
 const HEX_REGEX = /^0x[0-9A-F]*$/i;
 
diff --git a/packages/0x.js/src/utils/decorators.ts b/packages/0x.js/src/utils/decorators.ts
index ec750b891..1760d8872 100644
--- a/packages/0x.js/src/utils/decorators.ts
+++ b/packages/0x.js/src/utils/decorators.ts
@@ -1,7 +1,9 @@
 import * as _ from 'lodash';
-import {constants} from './constants';
+
 import {AsyncMethod, ZeroExError} from '../types';
 
+import {constants} from './constants';
+
 export const decorators = {
     /**
      * Source: https://stackoverflow.com/a/29837695/3546986
diff --git a/packages/0x.js/src/utils/exchange_transfer_simulator.ts b/packages/0x.js/src/utils/exchange_transfer_simulator.ts
index eeb6081cb..2574bd9ac 100644
--- a/packages/0x.js/src/utils/exchange_transfer_simulator.ts
+++ b/packages/0x.js/src/utils/exchange_transfer_simulator.ts
@@ -1,8 +1,9 @@
-import * as _ from 'lodash';
 import BigNumber from 'bignumber.js';
-import {ExchangeContractErrs, TradeSide, TransferType, BlockParamLiteral} from '../types';
+import * as _ from 'lodash';
+
 import {TokenWrapper} from '../contract_wrappers/token_wrapper';
 import {BalanceAndProxyAllowanceLazyStore} from '../stores/balance_proxy_allowance_lazy_store';
+import {BlockParamLiteral, ExchangeContractErrs, TradeSide, TransferType} from '../types';
 
 enum FailureReason {
     Balance = 'balance',
@@ -35,6 +36,11 @@ const ERR_MSG_MAPPING = {
 export class ExchangeTransferSimulator {
     private store: BalanceAndProxyAllowanceLazyStore;
     private UNLIMITED_ALLOWANCE_IN_BASE_UNITS: BigNumber;
+    private static throwValidationError(failureReason: FailureReason, tradeSide: TradeSide,
+                                        transferType: TransferType): never {
+        const errMsg = ERR_MSG_MAPPING[failureReason][tradeSide][transferType];
+        throw new Error(errMsg);
+    }
     constructor(token: TokenWrapper, defaultBlock: BlockParamLiteral) {
         this.store = new BalanceAndProxyAllowanceLazyStore(token, defaultBlock);
         this.UNLIMITED_ALLOWANCE_IN_BASE_UNITS = token.UNLIMITED_ALLOWANCE_IN_BASE_UNITS;
@@ -54,10 +60,10 @@ export class ExchangeTransferSimulator {
         const balance = await this.store.getBalanceAsync(tokenAddress, from);
         const proxyAllowance = await this.store.getProxyAllowanceAsync(tokenAddress, from);
         if (proxyAllowance.lessThan(amountInBaseUnits)) {
-            this.throwValidationError(FailureReason.ProxyAllowance, tradeSide, transferType);
+            ExchangeTransferSimulator.throwValidationError(FailureReason.ProxyAllowance, tradeSide, transferType);
         }
         if (balance.lessThan(amountInBaseUnits)) {
-            this.throwValidationError(FailureReason.Balance, tradeSide, transferType);
+            ExchangeTransferSimulator.throwValidationError(FailureReason.Balance, tradeSide, transferType);
         }
         await this.decreaseProxyAllowanceAsync(tokenAddress, from, amountInBaseUnits);
         await this.decreaseBalanceAsync(tokenAddress, from, amountInBaseUnits);
@@ -80,9 +86,4 @@ export class ExchangeTransferSimulator {
         const balance = await this.store.getBalanceAsync(tokenAddress, userAddress);
         this.store.setBalance(tokenAddress, userAddress, balance.minus(amountInBaseUnits));
     }
-    private throwValidationError(failureReason: FailureReason, tradeSide: TradeSide,
-                                 transferType: TransferType): Promise<never> {
-        const errMsg = ERR_MSG_MAPPING[failureReason][tradeSide][transferType];
-        throw new Error(errMsg);
-    }
 }
diff --git a/packages/0x.js/src/utils/filter_utils.ts b/packages/0x.js/src/utils/filter_utils.ts
index e09a95a6e..57c3ee71c 100644
--- a/packages/0x.js/src/utils/filter_utils.ts
+++ b/packages/0x.js/src/utils/filter_utils.ts
@@ -1,8 +1,9 @@
-import * as _ from 'lodash';
-import * as Web3 from 'web3';
-import * as uuid from 'uuid/v4';
 import * as ethUtil from 'ethereumjs-util';
 import * as jsSHA3 from 'js-sha3';
+import * as _ from 'lodash';
+import * as uuid from 'uuid/v4';
+import * as Web3 from 'web3';
+
 import {ContractEvents, IndexedFilterValues, SubscriptionOpts} from '../types';
 
 const TOPIC_LENGTH = 32;
diff --git a/packages/0x.js/src/utils/order_state_utils.ts b/packages/0x.js/src/utils/order_state_utils.ts
index 1d8f02a18..6b7f811ae 100644
--- a/packages/0x.js/src/utils/order_state_utils.ts
+++ b/packages/0x.js/src/utils/order_state_utils.ts
@@ -1,29 +1,61 @@
+import BigNumber from 'bignumber.js';
 import * as _ from 'lodash';
 import * as Web3 from 'web3';
-import BigNumber from 'bignumber.js';
+
+import {ZeroEx} from '../0x';
+import {ExchangeWrapper} from '../contract_wrappers/exchange_wrapper';
+import {TokenWrapper} from '../contract_wrappers/token_wrapper';
+import {RemainingFillableCalculator} from '../order_watcher/remaining_fillable_calculator';
+import {BalanceAndProxyAllowanceLazyStore} from '../stores/balance_proxy_allowance_lazy_store';
+import {OrderFilledCancelledLazyStore} from '../stores/order_filled_cancelled_lazy_store';
 import {
     ExchangeContractErrs,
-    SignedOrder,
-    OrderRelevantState,
     MethodOpts,
+    OrderRelevantState,
     OrderState,
-    OrderStateValid,
     OrderStateInvalid,
+    OrderStateValid,
+    SignedOrder,
 } from '../types';
-import {ZeroEx} from '../0x';
-import {TokenWrapper} from '../contract_wrappers/token_wrapper';
-import {ExchangeWrapper} from '../contract_wrappers/exchange_wrapper';
-import {utils} from '../utils/utils';
 import {constants} from '../utils/constants';
-import {OrderFilledCancelledLazyStore} from '../stores/order_filled_cancelled_lazy_store';
-import {BalanceAndProxyAllowanceLazyStore} from '../stores/balance_proxy_allowance_lazy_store';
-import {RemainingFillableCalculator} from '../order_watcher/remaining_fillable_calculator';
+import {utils} from '../utils/utils';
 
 const ACCEPTABLE_RELATIVE_ROUNDING_ERROR = 0.0001;
 
 export class OrderStateUtils {
     private balanceAndProxyAllowanceLazyStore: BalanceAndProxyAllowanceLazyStore;
     private orderFilledCancelledLazyStore: OrderFilledCancelledLazyStore;
+    private static validateIfOrderIsValid(signedOrder: SignedOrder, orderRelevantState: OrderRelevantState): void {
+        const unavailableTakerTokenAmount = orderRelevantState.cancelledTakerTokenAmount.add(
+            orderRelevantState.filledTakerTokenAmount,
+        );
+        const availableTakerTokenAmount = signedOrder.takerTokenAmount.minus(unavailableTakerTokenAmount);
+        if (availableTakerTokenAmount.eq(0)) {
+            throw new Error(ExchangeContractErrs.OrderRemainingFillAmountZero);
+        }
+
+        if (orderRelevantState.makerBalance.eq(0)) {
+            throw new Error(ExchangeContractErrs.InsufficientMakerBalance);
+        }
+        if (orderRelevantState.makerProxyAllowance.eq(0)) {
+            throw new Error(ExchangeContractErrs.InsufficientMakerAllowance);
+        }
+        if (!signedOrder.makerFee.eq(0)) {
+            if (orderRelevantState.makerFeeBalance.eq(0)) {
+                throw new Error(ExchangeContractErrs.InsufficientMakerFeeBalance);
+            }
+            if (orderRelevantState.makerFeeProxyAllowance.eq(0)) {
+                throw new Error(ExchangeContractErrs.InsufficientMakerFeeAllowance);
+            }
+        }
+        const minFillableTakerTokenAmountWithinNoRoundingErrorRange = signedOrder.takerTokenAmount
+                                                                      .dividedBy(ACCEPTABLE_RELATIVE_ROUNDING_ERROR)
+                                                                      .dividedBy(signedOrder.makerTokenAmount);
+        if (orderRelevantState.remainingFillableTakerTokenAmount
+            .lessThan(minFillableTakerTokenAmountWithinNoRoundingErrorRange)) {
+            throw new Error(ExchangeContractErrs.OrderFillRoundingError);
+        }
+    }
     constructor(balanceAndProxyAllowanceLazyStore: BalanceAndProxyAllowanceLazyStore,
                 orderFilledCancelledLazyStore: OrderFilledCancelledLazyStore) {
         this.balanceAndProxyAllowanceLazyStore = balanceAndProxyAllowanceLazyStore;
@@ -33,7 +65,7 @@ export class OrderStateUtils {
         const orderRelevantState = await this.getOrderRelevantStateAsync(signedOrder);
         const orderHash = ZeroEx.getOrderHashHex(signedOrder);
         try {
-            this.validateIfOrderIsValid(signedOrder, orderRelevantState);
+            OrderStateUtils.validateIfOrderIsValid(signedOrder, orderRelevantState);
             const orderState: OrderStateValid = {
                 isValid: true,
                 orderHash,
@@ -55,7 +87,7 @@ export class OrderStateUtils {
         // because JS doesn't support async constructors.
         // Moreover - it's cached under the hood so it's equivalent to an async constructor.
         const exchange = (this.orderFilledCancelledLazyStore as any).exchange as ExchangeWrapper;
-        const zrxTokenAddress = await exchange.getZRXTokenAddressAsync();
+        const zrxTokenAddress = exchange.getZRXTokenAddress();
         const orderHash = ZeroEx.getOrderHashHex(signedOrder);
         const makerBalance = await this.balanceAndProxyAllowanceLazyStore.getBalanceAsync(
             signedOrder.makerTokenAddress, signedOrder.maker,
@@ -102,37 +134,4 @@ export class OrderStateUtils {
         };
         return orderRelevantState;
     }
-    private validateIfOrderIsValid(signedOrder: SignedOrder, orderRelevantState: OrderRelevantState): void {
-        const unavailableTakerTokenAmount = orderRelevantState.cancelledTakerTokenAmount.add(
-            orderRelevantState.filledTakerTokenAmount,
-        );
-        const availableTakerTokenAmount = signedOrder.takerTokenAmount.minus(unavailableTakerTokenAmount);
-        if (availableTakerTokenAmount.eq(0)) {
-            throw new Error(ExchangeContractErrs.OrderRemainingFillAmountZero);
-        }
-
-        if (orderRelevantState.makerBalance.eq(0)) {
-            throw new Error(ExchangeContractErrs.InsufficientMakerBalance);
-        }
-        if (orderRelevantState.makerProxyAllowance.eq(0)) {
-            throw new Error(ExchangeContractErrs.InsufficientMakerAllowance);
-        }
-        if (!signedOrder.makerFee.eq(0)) {
-            if (orderRelevantState.makerFeeBalance.eq(0)) {
-                throw new Error(ExchangeContractErrs.InsufficientMakerFeeBalance);
-            }
-            if (orderRelevantState.makerFeeProxyAllowance.eq(0)) {
-                throw new Error(ExchangeContractErrs.InsufficientMakerFeeAllowance);
-            }
-        }
-        const minFillableTakerTokenAmountWithinNoRoundingErrorRange = signedOrder.takerTokenAmount
-                                                                      .dividedBy(ACCEPTABLE_RELATIVE_ROUNDING_ERROR)
-                                                                      .dividedBy(signedOrder.makerTokenAmount);
-        if (orderRelevantState.remainingFillableTakerTokenAmount
-            .lessThan(minFillableTakerTokenAmountWithinNoRoundingErrorRange)) {
-            throw new Error(ExchangeContractErrs.OrderFillRoundingError);
-        }
-        // TODO Add linear function solver when maker token is ZRX #badass
-        // Return the max amount that's fillable
-    }
 }
diff --git a/packages/0x.js/src/utils/order_validation_utils.ts b/packages/0x.js/src/utils/order_validation_utils.ts
index ed723e3d4..d514483e0 100644
--- a/packages/0x.js/src/utils/order_validation_utils.ts
+++ b/packages/0x.js/src/utils/order_validation_utils.ts
@@ -1,16 +1,89 @@
-import * as _ from 'lodash';
 import BigNumber from 'bignumber.js';
-import {ExchangeContractErrs, SignedOrder, Order, ZeroExError, TradeSide, TransferType} from '../types';
+import * as _ from 'lodash';
+
 import {ZeroEx} from '../0x';
-import {TokenWrapper} from '../contract_wrappers/token_wrapper';
 import {ExchangeWrapper} from '../contract_wrappers/exchange_wrapper';
-import {utils} from '../utils/utils';
+import {TokenWrapper} from '../contract_wrappers/token_wrapper';
+import {ExchangeContractErrs, Order, SignedOrder, TradeSide, TransferType, ZeroExError} from '../types';
 import {constants} from '../utils/constants';
+import {utils} from '../utils/utils';
+
 import {ExchangeTransferSimulator} from './exchange_transfer_simulator';
 
 export class OrderValidationUtils {
     private tokenWrapper: TokenWrapper;
     private exchangeWrapper: ExchangeWrapper;
+    public static validateCancelOrderThrowIfInvalid(
+        order: Order, cancelTakerTokenAmount: BigNumber, unavailableTakerTokenAmount: BigNumber,
+    ): void {
+        if (cancelTakerTokenAmount.eq(0)) {
+            throw new Error(ExchangeContractErrs.OrderCancelAmountZero);
+        }
+        if (order.takerTokenAmount.eq(unavailableTakerTokenAmount)) {
+            throw new Error(ExchangeContractErrs.OrderAlreadyCancelledOrFilled);
+        }
+        const currentUnixTimestampSec = utils.getCurrentUnixTimestampSec();
+        if (order.expirationUnixTimestampSec.lessThan(currentUnixTimestampSec)) {
+            throw new Error(ExchangeContractErrs.OrderCancelExpired);
+        }
+    }
+    public static async validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
+        exchangeTradeEmulator: ExchangeTransferSimulator, signedOrder: SignedOrder,
+        fillTakerTokenAmount: BigNumber, senderAddress: string, zrxTokenAddress: string,
+    ): Promise<void> {
+        const fillMakerTokenAmount = OrderValidationUtils.getPartialAmount(
+            fillTakerTokenAmount,
+            signedOrder.takerTokenAmount,
+            signedOrder.makerTokenAmount,
+        );
+        await exchangeTradeEmulator.transferFromAsync(
+            signedOrder.makerTokenAddress, signedOrder.maker, senderAddress, fillMakerTokenAmount,
+            TradeSide.Maker, TransferType.Trade,
+        );
+        await exchangeTradeEmulator.transferFromAsync(
+            signedOrder.takerTokenAddress, senderAddress, signedOrder.maker, fillTakerTokenAmount,
+            TradeSide.Taker, TransferType.Trade,
+        );
+        const makerFeeAmount = OrderValidationUtils.getPartialAmount(
+            fillTakerTokenAmount,
+            signedOrder.takerTokenAmount,
+            signedOrder.makerFee,
+        );
+        await exchangeTradeEmulator.transferFromAsync(
+            zrxTokenAddress, signedOrder.maker, signedOrder.feeRecipient, makerFeeAmount, TradeSide.Maker,
+            TransferType.Fee,
+        );
+        const takerFeeAmount = OrderValidationUtils.getPartialAmount(
+            fillTakerTokenAmount,
+            signedOrder.takerTokenAmount,
+            signedOrder.takerFee,
+        );
+        await exchangeTradeEmulator.transferFromAsync(
+            zrxTokenAddress, senderAddress, signedOrder.feeRecipient, takerFeeAmount, TradeSide.Taker,
+            TransferType.Fee,
+        );
+    }
+    private static validateRemainingFillAmountNotZeroOrThrow(
+        takerTokenAmount: BigNumber, unavailableTakerTokenAmount: BigNumber,
+    ) {
+        if (takerTokenAmount.eq(unavailableTakerTokenAmount)) {
+            throw new Error(ExchangeContractErrs.OrderRemainingFillAmountZero);
+        }
+    }
+    private static validateOrderNotExpiredOrThrow(expirationUnixTimestampSec: BigNumber) {
+        const currentUnixTimestampSec = utils.getCurrentUnixTimestampSec();
+        if (expirationUnixTimestampSec.lessThan(currentUnixTimestampSec)) {
+            throw new Error(ExchangeContractErrs.OrderFillExpired);
+        }
+    }
+    private static getPartialAmount(numerator: BigNumber, denominator: BigNumber,
+                                    target: BigNumber): BigNumber {
+        const fillMakerTokenAmount = numerator
+                                     .mul(target)
+                                     .div(denominator)
+                                     .round(0);
+        return fillMakerTokenAmount;
+    }
     constructor(tokenWrapper: TokenWrapper, exchangeWrapper: ExchangeWrapper) {
         this.tokenWrapper = tokenWrapper;
         this.exchangeWrapper = exchangeWrapper;
@@ -20,15 +93,15 @@ export class OrderValidationUtils {
         expectedFillTakerTokenAmount?: BigNumber): Promise<void> {
         const orderHash = utils.getOrderHashHex(signedOrder);
         const unavailableTakerTokenAmount = await this.exchangeWrapper.getUnavailableTakerAmountAsync(orderHash);
-        this.validateRemainingFillAmountNotZeroOrThrow(
+        OrderValidationUtils.validateRemainingFillAmountNotZeroOrThrow(
             signedOrder.takerTokenAmount, unavailableTakerTokenAmount,
         );
-        this.validateOrderNotExpiredOrThrow(signedOrder.expirationUnixTimestampSec);
+        OrderValidationUtils.validateOrderNotExpiredOrThrow(signedOrder.expirationUnixTimestampSec);
         let fillTakerTokenAmount = signedOrder.takerTokenAmount.minus(unavailableTakerTokenAmount);
         if (!_.isUndefined(expectedFillTakerTokenAmount)) {
             fillTakerTokenAmount = expectedFillTakerTokenAmount;
         }
-        const fillMakerTokenAmount = this.getPartialAmount(
+        const fillMakerTokenAmount = OrderValidationUtils.getPartialAmount(
             fillTakerTokenAmount,
             signedOrder.takerTokenAmount,
             signedOrder.makerTokenAmount,
@@ -37,7 +110,7 @@ export class OrderValidationUtils {
             signedOrder.makerTokenAddress, signedOrder.maker, signedOrder.taker, fillMakerTokenAmount,
             TradeSide.Maker, TransferType.Trade,
         );
-        const makerFeeAmount = this.getPartialAmount(
+        const makerFeeAmount = OrderValidationUtils.getPartialAmount(
             fillTakerTokenAmount,
             signedOrder.takerTokenAmount,
             signedOrder.makerFee,
@@ -59,18 +132,18 @@ export class OrderValidationUtils {
             throw new Error(ZeroExError.InvalidSignature);
         }
         const unavailableTakerTokenAmount = await this.exchangeWrapper.getUnavailableTakerAmountAsync(orderHash);
-        this.validateRemainingFillAmountNotZeroOrThrow(
+        OrderValidationUtils.validateRemainingFillAmountNotZeroOrThrow(
             signedOrder.takerTokenAmount, unavailableTakerTokenAmount,
         );
         if (signedOrder.taker !== constants.NULL_ADDRESS && signedOrder.taker !== takerAddress) {
             throw new Error(ExchangeContractErrs.TransactionSenderIsNotFillOrderTaker);
         }
-        this.validateOrderNotExpiredOrThrow(signedOrder.expirationUnixTimestampSec);
+        OrderValidationUtils.validateOrderNotExpiredOrThrow(signedOrder.expirationUnixTimestampSec);
         const remainingTakerTokenAmount = signedOrder.takerTokenAmount.minus(unavailableTakerTokenAmount);
         const filledTakerTokenAmount = remainingTakerTokenAmount.lessThan(fillTakerTokenAmount) ?
                                        remainingTakerTokenAmount :
                                        fillTakerTokenAmount;
-        await this.validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
+        await OrderValidationUtils.validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
             exchangeTradeEmulator, signedOrder, filledTakerTokenAmount, takerAddress, zrxTokenAddress,
         );
 
@@ -92,75 +165,4 @@ export class OrderValidationUtils {
             throw new Error(ExchangeContractErrs.InsufficientRemainingFillAmount);
         }
     }
-    public async validateCancelOrderThrowIfInvalidAsync(order: Order,
-                                                        cancelTakerTokenAmount: BigNumber,
-                                                        unavailableTakerTokenAmount: BigNumber,
-    ): Promise<void> {
-        if (cancelTakerTokenAmount.eq(0)) {
-            throw new Error(ExchangeContractErrs.OrderCancelAmountZero);
-        }
-        if (order.takerTokenAmount.eq(unavailableTakerTokenAmount)) {
-            throw new Error(ExchangeContractErrs.OrderAlreadyCancelledOrFilled);
-        }
-        const currentUnixTimestampSec = utils.getCurrentUnixTimestampSec();
-        if (order.expirationUnixTimestampSec.lessThan(currentUnixTimestampSec)) {
-            throw new Error(ExchangeContractErrs.OrderCancelExpired);
-        }
-    }
-    public async validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
-        exchangeTradeEmulator: ExchangeTransferSimulator, signedOrder: SignedOrder,
-        fillTakerTokenAmount: BigNumber, senderAddress: string, zrxTokenAddress: string): Promise<void> {
-        const fillMakerTokenAmount = this.getPartialAmount(
-            fillTakerTokenAmount,
-            signedOrder.takerTokenAmount,
-            signedOrder.makerTokenAmount,
-        );
-        await exchangeTradeEmulator.transferFromAsync(
-            signedOrder.makerTokenAddress, signedOrder.maker, senderAddress, fillMakerTokenAmount,
-            TradeSide.Maker, TransferType.Trade,
-        );
-        await exchangeTradeEmulator.transferFromAsync(
-            signedOrder.takerTokenAddress, senderAddress, signedOrder.maker, fillTakerTokenAmount,
-            TradeSide.Taker, TransferType.Trade,
-        );
-        const makerFeeAmount = this.getPartialAmount(
-            fillTakerTokenAmount,
-            signedOrder.takerTokenAmount,
-            signedOrder.makerFee,
-        );
-        await exchangeTradeEmulator.transferFromAsync(
-            zrxTokenAddress, signedOrder.maker, signedOrder.feeRecipient, makerFeeAmount, TradeSide.Maker,
-            TransferType.Fee,
-        );
-        const takerFeeAmount = this.getPartialAmount(
-            fillTakerTokenAmount,
-            signedOrder.takerTokenAmount,
-            signedOrder.takerFee,
-        );
-        await exchangeTradeEmulator.transferFromAsync(
-            zrxTokenAddress, senderAddress, signedOrder.feeRecipient, takerFeeAmount, TradeSide.Taker,
-            TransferType.Fee,
-        );
-    }
-    private validateRemainingFillAmountNotZeroOrThrow(
-        takerTokenAmount: BigNumber, unavailableTakerTokenAmount: BigNumber,
-    ) {
-        if (takerTokenAmount.eq(unavailableTakerTokenAmount)) {
-            throw new Error(ExchangeContractErrs.OrderRemainingFillAmountZero);
-        }
-    }
-    private validateOrderNotExpiredOrThrow(expirationUnixTimestampSec: BigNumber) {
-        const currentUnixTimestampSec = utils.getCurrentUnixTimestampSec();
-        if (expirationUnixTimestampSec.lessThan(currentUnixTimestampSec)) {
-            throw new Error(ExchangeContractErrs.OrderFillExpired);
-        }
-    }
-    private getPartialAmount(numerator: BigNumber, denominator: BigNumber,
-                             target: BigNumber): BigNumber {
-        const fillMakerTokenAmount = numerator
-                                     .mul(target)
-                                     .div(denominator)
-                                     .round(0);
-        return fillMakerTokenAmount;
-    }
 }
diff --git a/packages/0x.js/src/utils/signature_utils.ts b/packages/0x.js/src/utils/signature_utils.ts
index d066f8bf0..aaf04e7b0 100644
--- a/packages/0x.js/src/utils/signature_utils.ts
+++ b/packages/0x.js/src/utils/signature_utils.ts
@@ -1,4 +1,5 @@
 import * as ethUtil from 'ethereumjs-util';
+
 import {ECSignature} from '../types';
 
 export const signatureUtils = {
diff --git a/packages/0x.js/src/utils/utils.ts b/packages/0x.js/src/utils/utils.ts
index 5370c3b4b..04ae34aac 100644
--- a/packages/0x.js/src/utils/utils.ts
+++ b/packages/0x.js/src/utils/utils.ts
@@ -1,9 +1,10 @@
-import * as _ from 'lodash';
+import BigNumber from 'bignumber.js';
+import BN = require('bn.js');
 import * as ethABI from 'ethereumjs-abi';
 import * as ethUtil from 'ethereumjs-util';
+import * as _ from 'lodash';
+
 import {Order, SignedOrder, SolidityTypes} from '../types';
-import BigNumber from 'bignumber.js';
-import BN = require('bn.js');
 
 export const utils = {
     /**
diff --git a/packages/0x.js/src/web3_wrapper.ts b/packages/0x.js/src/web3_wrapper.ts
index 7bd8ea093..a031de486 100644
--- a/packages/0x.js/src/web3_wrapper.ts
+++ b/packages/0x.js/src/web3_wrapper.ts
@@ -1,9 +1,10 @@
-import * as _ from 'lodash';
-import * as Web3 from 'web3';
 import BigNumber from 'bignumber.js';
 import promisify = require('es6-promisify');
-import {ZeroExError, Artifact, TransactionReceipt} from './types';
+import * as _ from 'lodash';
+import * as Web3 from 'web3';
+
 import {Contract} from './contract';
+import {Artifact, ArtifactContractName, TransactionReceipt, ZeroExError} from './types';
 
 interface RawLogEntry {
     logIndex: string|null;
@@ -16,12 +17,21 @@ interface RawLogEntry {
     topics: string[];
 }
 
+const CONTRACT_NAME_TO_NOT_FOUND_ERROR: {[contractName: string]: ZeroExError} = {
+    ZRX: ZeroExError.ZRXContractDoesNotExist,
+    EtherToken: ZeroExError.EtherTokenContractDoesNotExist,
+    Token: ZeroExError.TokenContractDoesNotExist,
+    TokenRegistry: ZeroExError.TokenRegistryContractDoesNotExist,
+    TokenTransferProxy: ZeroExError.TokenTransferProxyContractDoesNotExist,
+    Exchange: ZeroExError.ExchangeContractDoesNotExist,
+};
+
 export class Web3Wrapper {
     private web3: Web3;
+    private networkId: number;
     private defaults: Partial<Web3.TxData>;
-    private networkIdIfExists?: number;
     private jsonRpcRequestId: number;
-    constructor(provider: Web3.Provider, defaults?: Partial<Web3.TxData>) {
+    constructor(provider: Web3.Provider, networkId: number, defaults?: Partial<Web3.TxData>) {
         if (_.isUndefined((provider as any).sendAsync)) {
             // Web3@1.0 provider doesn't support synchronous http requests,
             // so it only has an async `send` method, instead of a `send` and `sendAsync` in web3@0.x.x`
@@ -29,12 +39,13 @@ export class Web3Wrapper {
             (provider as any).sendAsync = (provider as any).send;
         }
         this.web3 = new Web3();
+        this.networkId = networkId;
         this.web3.setProvider(provider);
         this.defaults = defaults || {};
         this.jsonRpcRequestId = 0;
     }
-    public setProvider(provider: Web3.Provider) {
-        delete this.networkIdIfExists;
+    public setProvider(provider: Web3.Provider, networkId: number) {
+        this.networkId = networkId;
         this.web3.setProvider(provider);
     }
     public isAddress(address: string): boolean {
@@ -58,37 +69,24 @@ export class Web3Wrapper {
     public getCurrentProvider(): Web3.Provider {
         return this.web3.currentProvider;
     }
-    public async getNetworkIdIfExistsAsync(): Promise<number|undefined> {
-        if (!_.isUndefined(this.networkIdIfExists)) {
-          return this.networkIdIfExists;
-        }
-
-        try {
-            const networkId = await this.getNetworkAsync();
-            this.networkIdIfExists = Number(networkId);
-            return this.networkIdIfExists;
-        } catch (err) {
-            return undefined;
-        }
+    public getNetworkId(): number {
+        return this.networkId;
     }
     public async getContractInstanceFromArtifactAsync<A extends Web3.ContractInstance>(artifact: Artifact,
                                                                                        address?: string): Promise<A> {
         let contractAddress: string;
         if (_.isUndefined(address)) {
-            const networkIdIfExists = await this.getNetworkIdIfExistsAsync();
-            if (_.isUndefined(networkIdIfExists)) {
-                throw new Error(ZeroExError.NoNetworkId);
-            }
-            if (_.isUndefined(artifact.networks[networkIdIfExists])) {
+            const networkId = this.getNetworkId();
+            if (_.isUndefined(artifact.networks[networkId])) {
                 throw new Error(ZeroExError.ContractNotDeployedOnNetwork);
             }
-            contractAddress = artifact.networks[networkIdIfExists].address.toLowerCase();
+            contractAddress = artifact.networks[networkId].address.toLowerCase();
         } else {
             contractAddress = address;
         }
         const doesContractExist = await this.doesContractExistAtAddressAsync(contractAddress);
         if (!doesContractExist) {
-            throw new Error(ZeroExError.ContractDoesNotExist);
+            throw new Error(CONTRACT_NAME_TO_NOT_FOUND_ERROR[artifact.contract_name]);
         }
         const contractInstance = this.getContractInstance<A>(
             artifact.abi, contractAddress,
diff --git a/packages/0x.js/test/0x.js_test.ts b/packages/0x.js/test/0x.js_test.ts
index d56acc38b..6b7a70699 100644
--- a/packages/0x.js/test/0x.js_test.ts
+++ b/packages/0x.js/test/0x.js_test.ts
@@ -1,14 +1,16 @@
-import * as _ from 'lodash';
+import BigNumber from 'bignumber.js';
 import * as chai from 'chai';
-import {chaiSetup} from './utils/chai_setup';
+import * as _ from 'lodash';
 import 'mocha';
-import BigNumber from 'bignumber.js';
 import * as Sinon from 'sinon';
-import {ZeroEx, Order, ZeroExError, LogWithDecodedArgs, ApprovalContractEventArgs, TokenEvents} from '../src';
+
+import {ApprovalContractEventArgs, LogWithDecodedArgs, Order, TokenEvents, ZeroEx, ZeroExError} from '../src';
+
+import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
+import {chaiSetup} from './utils/chai_setup';
 import {constants} from './utils/constants';
 import {TokenUtils} from './utils/token_utils';
 import {web3Factory} from './utils/web3_factory';
-import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
 
 const blockchainLifecycle = new BlockchainLifecycle();
 chaiSetup.configure();
@@ -16,7 +18,10 @@ const expect = chai.expect;
 
 describe('ZeroEx library', () => {
     const web3 = web3Factory.create();
-    const zeroEx = new ZeroEx(web3.currentProvider);
+    const config = {
+        networkId: constants.TESTRPC_NETWORK_ID,
+    };
+    const zeroEx = new ZeroEx(web3.currentProvider, config);
     describe('#setProvider', () => {
         it('overrides provider in nested web3s and invalidates contractInstances', async () => {
             // Instantiate the contract instances with the current provider
@@ -28,7 +33,7 @@ describe('ZeroEx library', () => {
             const newProvider = web3Factory.getRpcProvider();
             // Add property to newProvider so that we can differentiate it from old provider
             (newProvider as any).zeroExTestId = 1;
-            await zeroEx.setProviderAsync(newProvider);
+            zeroEx.setProvider(newProvider, constants.TESTRPC_NETWORK_ID);
 
             // Check that contractInstances with old provider are removed after provider update
             expect((zeroEx.exchange as any)._exchangeContractIfExists).to.be.undefined();
@@ -36,11 +41,11 @@ describe('ZeroEx library', () => {
 
             // Check that all nested web3 wrapper instances return the updated provider
             const nestedWeb3WrapperProvider = (zeroEx as any)._web3Wrapper.getCurrentProvider();
-            expect((nestedWeb3WrapperProvider as any).zeroExTestId).to.be.a('number');
+            expect((nestedWeb3WrapperProvider).zeroExTestId).to.be.a('number');
             const exchangeWeb3WrapperProvider = (zeroEx.exchange as any)._web3Wrapper.getCurrentProvider();
-            expect((exchangeWeb3WrapperProvider as any).zeroExTestId).to.be.a('number');
+            expect((exchangeWeb3WrapperProvider).zeroExTestId).to.be.a('number');
             const tokenRegistryWeb3WrapperProvider = (zeroEx.tokenRegistry as any)._web3Wrapper.getCurrentProvider();
-            expect((tokenRegistryWeb3WrapperProvider as any).zeroExTestId).to.be.a('number');
+            expect((tokenRegistryWeb3WrapperProvider).zeroExTestId).to.be.a('number');
         });
     });
     describe('#isValidSignature', () => {
@@ -220,7 +225,7 @@ describe('ZeroEx library', () => {
             const tokens = await zeroEx.tokenRegistry.getTokensAsync();
             const tokenUtils = new TokenUtils(tokens);
             const zrxTokenAddress = tokenUtils.getProtocolTokenOrThrow().address;
-            const proxyAddress = await zeroEx.proxy.getContractAddressAsync();
+            const proxyAddress = zeroEx.proxy.getContractAddress();
             const txHash = await zeroEx.token.setUnlimitedProxyAllowanceAsync(zrxTokenAddress, coinbase);
             const txReceiptWithDecodedLogs = await zeroEx.awaitTransactionMinedAsync(txHash);
             const log = txReceiptWithDecodedLogs.logs[0] as LogWithDecodedArgs<ApprovalContractEventArgs>;
@@ -232,28 +237,29 @@ describe('ZeroEx library', () => {
     });
     describe('#config', () => {
         it('allows to specify exchange contract address', async () => {
-            const config = {
+            const zeroExConfig = {
                 exchangeContractAddress: ZeroEx.NULL_ADDRESS,
+                networkId: constants.TESTRPC_NETWORK_ID,
             };
-            const zeroExWithWrongExchangeAddress = new ZeroEx(web3.currentProvider, config);
-            return expect(zeroExWithWrongExchangeAddress.exchange.getContractAddressAsync())
-                .to.be.rejectedWith(ZeroExError.ContractDoesNotExist);
+            const zeroExWithWrongExchangeAddress = new ZeroEx(web3.currentProvider, zeroExConfig);
+            expect(zeroExWithWrongExchangeAddress.exchange.getContractAddress()).to.be.equal(ZeroEx.NULL_ADDRESS);
         });
         it('allows to specify ether token contract address', async () => {
-            const config = {
+            const zeroExConfig = {
                 etherTokenContractAddress: ZeroEx.NULL_ADDRESS,
+                networkId: constants.TESTRPC_NETWORK_ID,
             };
-            const zeroExWithWrongEtherTokenAddress = new ZeroEx(web3.currentProvider, config);
-            return expect(zeroExWithWrongEtherTokenAddress.etherToken.getContractAddressAsync())
-                .to.be.rejectedWith(ZeroExError.ContractDoesNotExist);
+            const zeroExWithWrongEtherTokenAddress = new ZeroEx(web3.currentProvider, zeroExConfig);
+            expect(zeroExWithWrongEtherTokenAddress.etherToken.getContractAddress()).to.be.equal(ZeroEx.NULL_ADDRESS);
         });
         it('allows to specify token registry token contract address', async () => {
-            const config = {
+            const zeroExConfig = {
                 tokenRegistryContractAddress: ZeroEx.NULL_ADDRESS,
+                networkId: constants.TESTRPC_NETWORK_ID,
             };
-            const zeroExWithWrongTokenRegistryAddress = new ZeroEx(web3.currentProvider, config);
-            return expect(zeroExWithWrongTokenRegistryAddress.tokenRegistry.getContractAddressAsync())
-                .to.be.rejectedWith(ZeroExError.ContractDoesNotExist);
+            const zeroExWithWrongTokenRegistryAddress = new ZeroEx(web3.currentProvider, zeroExConfig);
+            expect(zeroExWithWrongTokenRegistryAddress.tokenRegistry.getContractAddress())
+                .to.be.equal(ZeroEx.NULL_ADDRESS);
         });
     });
 });
diff --git a/packages/0x.js/test/artifacts_test.ts b/packages/0x.js/test/artifacts_test.ts
index b2866a1d6..f4599a24d 100644
--- a/packages/0x.js/test/artifacts_test.ts
+++ b/packages/0x.js/test/artifacts_test.ts
@@ -1,8 +1,10 @@
-import * as fs from 'fs';
 import * as chai from 'chai';
-import {chaiSetup} from './utils/chai_setup';
+import * as fs from 'fs';
 import HDWalletProvider = require('truffle-hdwallet-provider');
+
 import {ZeroEx} from '../src';
+
+import {chaiSetup} from './utils/chai_setup';
 import {constants} from './utils/constants';
 
 chaiSetup.configure();
@@ -18,15 +20,18 @@ describe('Artifacts', () => {
         const packageJSON = JSON.parse(packageJSONContent);
         const mnemonic = packageJSON.config.mnemonic;
         const web3Provider = new HDWalletProvider(mnemonic, kovanRpcUrl);
-        const zeroEx = new ZeroEx(web3Provider);
+        const config = {
+            networkId: constants.KOVAN_NETWORK_ID,
+        };
+        const zeroEx = new ZeroEx(web3Provider, config);
         it('token registry contract is deployed', async () => {
             await (zeroEx.tokenRegistry as any)._getTokenRegistryContractAsync();
         }).timeout(TIMEOUT);
         it('proxy contract is deployed', async () => {
-            await (zeroEx.token as any)._getTokenTransferProxyAddressAsync();
+            await (zeroEx.proxy as any)._getTokenTransferProxyContractAsync();
         }).timeout(TIMEOUT);
         it('exchange contract is deployed', async () => {
-            await zeroEx.exchange.getContractAddressAsync();
+            await (zeroEx.exchange as any)._getExchangeContractAsync();
         }).timeout(TIMEOUT);
     });
     describe('contracts are deployed on ropsten', () => {
@@ -35,15 +40,18 @@ describe('Artifacts', () => {
         const packageJSON = JSON.parse(packageJSONContent);
         const mnemonic = packageJSON.config.mnemonic;
         const web3Provider = new HDWalletProvider(mnemonic, ropstenRpcUrl);
-        const zeroEx = new ZeroEx(web3Provider);
+        const config = {
+            networkId: constants.ROPSTEN_NETWORK_ID,
+        };
+        const zeroEx = new ZeroEx(web3Provider, config);
         it('token registry contract is deployed', async () => {
             await (zeroEx.tokenRegistry as any)._getTokenRegistryContractAsync();
         }).timeout(TIMEOUT);
         it('proxy contract is deployed', async () => {
-            await (zeroEx.token as any)._getTokenTransferProxyAddressAsync();
+            await (zeroEx.proxy as any)._getTokenTransferProxyContractAsync();
         }).timeout(TIMEOUT);
         it('exchange contract is deployed', async () => {
-            await zeroEx.exchange.getContractAddressAsync();
+            await (zeroEx.exchange as any)._getExchangeContractAsync();
         }).timeout(TIMEOUT);
     });
 });
diff --git a/packages/0x.js/test/assert_test.ts b/packages/0x.js/test/assert_test.ts
index bfca95d9c..9fa7f780f 100644
--- a/packages/0x.js/test/assert_test.ts
+++ b/packages/0x.js/test/assert_test.ts
@@ -1,14 +1,20 @@
 import * as chai from 'chai';
 import 'mocha';
+
 import {ZeroEx} from '../src';
 import {assert} from '../src/utils/assert';
+
+import {constants} from './utils/constants';
 import {web3Factory} from './utils/web3_factory';
 
 const expect = chai.expect;
 
 describe('Assertion library', () => {
     const web3 = web3Factory.create();
-    const zeroEx = new ZeroEx(web3.currentProvider);
+    const config = {
+        networkId: constants.TESTRPC_NETWORK_ID,
+    };
+    const zeroEx = new ZeroEx(web3.currentProvider, config);
     describe('#isSenderAddressHexAsync', () => {
         it('throws when address is invalid', async () => {
             const address = '0xdeadbeef';
diff --git a/packages/0x.js/test/ether_token_wrapper_test.ts b/packages/0x.js/test/ether_token_wrapper_test.ts
index ba679d1a1..5b5e4c656 100644
--- a/packages/0x.js/test/ether_token_wrapper_test.ts
+++ b/packages/0x.js/test/ether_token_wrapper_test.ts
@@ -1,11 +1,14 @@
-import 'mocha';
+import BigNumber from 'bignumber.js';
 import * as chai from 'chai';
-import {chaiSetup} from './utils/chai_setup';
+import 'mocha';
 import * as Web3 from 'web3';
-import BigNumber from 'bignumber.js';
-import {web3Factory} from './utils/web3_factory';
+
 import {ZeroEx, ZeroExError} from '../src';
+
 import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
+import {chaiSetup} from './utils/chai_setup';
+import {constants} from './utils/constants';
+import {web3Factory} from './utils/web3_factory';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -28,13 +31,14 @@ describe('EtherTokenWrapper', () => {
     const gasPrice = new BigNumber(1);
     const zeroExConfig = {
         gasPrice,
+        networkId: constants.TESTRPC_NETWORK_ID,
     };
     before(async () => {
         web3 = web3Factory.create();
         zeroEx = new ZeroEx(web3.currentProvider, zeroExConfig);
         userAddresses = await zeroEx.getAvailableAddressesAsync();
         addressWithETH = userAddresses[0];
-        wethContractAddress = await zeroEx.etherToken.getContractAddressAsync();
+        wethContractAddress = zeroEx.etherToken.getContractAddress();
         depositWeiAmount = (zeroEx as any)._web3Wrapper.toWei(new BigNumber(5));
         decimalPlaces = 7;
     });
diff --git a/packages/0x.js/test/event_watcher_test.ts b/packages/0x.js/test/event_watcher_test.ts
index b4164fe63..f27a7da2c 100644
--- a/packages/0x.js/test/event_watcher_test.ts
+++ b/packages/0x.js/test/event_watcher_test.ts
@@ -1,19 +1,22 @@
-import 'mocha';
+import BigNumber from 'bignumber.js';
 import * as chai from 'chai';
 import * as _ from 'lodash';
+import 'mocha';
 import * as Sinon from 'sinon';
 import * as Web3 from 'web3';
-import BigNumber from 'bignumber.js';
-import {chaiSetup} from './utils/chai_setup';
-import {web3Factory} from './utils/web3_factory';
-import {Web3Wrapper} from '../src/web3_wrapper';
-import {EventWatcher} from '../src/order_watcher/event_watcher';
+
 import {
-    ZeroEx,
-    LogEvent,
     DecodedLogEvent,
+    LogEvent,
+    ZeroEx,
 } from '../src';
+import {EventWatcher} from '../src/order_watcher/event_watcher';
 import {DoneCallback} from '../src/types';
+import {Web3Wrapper} from '../src/web3_wrapper';
+
+import {chaiSetup} from './utils/chai_setup';
+import {constants} from './utils/constants';
+import {web3Factory} from './utils/web3_factory';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -57,7 +60,7 @@ describe('EventWatcher', () => {
     before(async () => {
         web3 = web3Factory.create();
         const pollingIntervalMs = 10;
-        web3Wrapper = new Web3Wrapper(web3.currentProvider);
+        web3Wrapper = new Web3Wrapper(web3.currentProvider, constants.TESTRPC_NETWORK_ID);
         eventWatcher = new EventWatcher(web3Wrapper, pollingIntervalMs);
     });
     afterEach(() => {
diff --git a/packages/0x.js/test/exchange_transfer_simulator_test.ts b/packages/0x.js/test/exchange_transfer_simulator_test.ts
index 43a6404a1..a1d9bdade 100644
--- a/packages/0x.js/test/exchange_transfer_simulator_test.ts
+++ b/packages/0x.js/test/exchange_transfer_simulator_test.ts
@@ -1,11 +1,14 @@
-import * as chai from 'chai';
 import BigNumber from 'bignumber.js';
+import * as chai from 'chai';
+
+import {ExchangeContractErrs, Token, ZeroEx} from '../src';
+import {BlockParamLiteral, TradeSide, TransferType} from '../src/types';
+import {ExchangeTransferSimulator} from '../src/utils/exchange_transfer_simulator';
+
+import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
 import {chaiSetup} from './utils/chai_setup';
+import {constants} from './utils/constants';
 import {web3Factory} from './utils/web3_factory';
-import {ZeroEx, ExchangeContractErrs, Token} from '../src';
-import {TradeSide, TransferType, BlockParamLiteral} from '../src/types';
-import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
-import {ExchangeTransferSimulator} from '../src/utils/exchange_transfer_simulator';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -13,7 +16,10 @@ const blockchainLifecycle = new BlockchainLifecycle();
 
 describe('ExchangeTransferSimulator', () => {
     const web3 = web3Factory.create();
-    const zeroEx = new ZeroEx(web3.currentProvider);
+    const config = {
+        networkId: constants.TESTRPC_NETWORK_ID,
+    };
+    const zeroEx = new ZeroEx(web3.currentProvider, config);
     const transferAmount = new BigNumber(5);
     let userAddresses: string[];
     let tokens: Token[];
diff --git a/packages/0x.js/test/exchange_wrapper_test.ts b/packages/0x.js/test/exchange_wrapper_test.ts
index 13ac4c1d3..f6c823cc4 100644
--- a/packages/0x.js/test/exchange_wrapper_test.ts
+++ b/packages/0x.js/test/exchange_wrapper_test.ts
@@ -1,27 +1,30 @@
-import 'mocha';
+import BigNumber from 'bignumber.js';
 import * as chai from 'chai';
+import 'mocha';
 import * as Web3 from 'web3';
-import BigNumber from 'bignumber.js';
-import {chaiSetup} from './utils/chai_setup';
-import {web3Factory} from './utils/web3_factory';
-import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
+
 import {
-    ZeroEx,
-    Token,
-    SignedOrder,
-    SubscriptionOpts,
-    ExchangeEvents,
+    DecodedLogEvent,
     ExchangeContractErrs,
-    OrderCancellationRequest,
-    OrderFillRequest,
-    LogFillContractEventArgs,
+    ExchangeEvents,
     LogCancelContractEventArgs,
     LogEvent,
-    DecodedLogEvent,
+    LogFillContractEventArgs,
+    OrderCancellationRequest,
+    OrderFillRequest,
+    SignedOrder,
+    SubscriptionOpts,
+    Token,
+    ZeroEx,
 } from '../src';
-import {DoneCallback, BlockParamLiteral} from '../src/types';
+import {BlockParamLiteral, DoneCallback} from '../src/types';
+
+import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
+import {chaiSetup} from './utils/chai_setup';
+import {constants} from './utils/constants';
 import {FillScenarios} from './utils/fill_scenarios';
 import {TokenUtils} from './utils/token_utils';
+import {web3Factory} from './utils/web3_factory';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -38,10 +41,13 @@ describe('ExchangeWrapper', () => {
     let zrxTokenAddress: string;
     let fillScenarios: FillScenarios;
     let exchangeContractAddress: string;
+    const config = {
+        networkId: constants.TESTRPC_NETWORK_ID,
+    };
     before(async () => {
         web3 = web3Factory.create();
-        zeroEx = new ZeroEx(web3.currentProvider);
-        exchangeContractAddress = await zeroEx.exchange.getContractAddressAsync();
+        zeroEx = new ZeroEx(web3.currentProvider, config);
+        exchangeContractAddress = zeroEx.exchange.getContractAddress();
         userAddresses = await zeroEx.getAvailableAddressesAsync();
         tokens = await zeroEx.tokenRegistry.getTokensAsync();
         tokenUtils = new TokenUtils(tokens);
@@ -613,7 +619,7 @@ describe('ExchangeWrapper', () => {
             });
         });
     });
-    describe('#subscribeAsync', () => {
+    describe('#subscribe', () => {
         const indexFilterValues = {};
         const shouldThrowOnInsufficientBalanceOrAllowance = true;
         let makerTokenAddress: string;
@@ -652,7 +658,7 @@ describe('ExchangeWrapper', () => {
                     expect(logEvent.log.event).to.be.equal(ExchangeEvents.LogFill);
                     done();
                 };
-                await zeroEx.exchange.subscribeAsync(
+                zeroEx.exchange.subscribe(
                     ExchangeEvents.LogFill, indexFilterValues, callback,
                 );
                 await zeroEx.exchange.fillOrderAsync(
@@ -668,7 +674,7 @@ describe('ExchangeWrapper', () => {
                     expect(logEvent.log.event).to.be.equal(ExchangeEvents.LogCancel);
                     done();
                 };
-                await zeroEx.exchange.subscribeAsync(
+                zeroEx.exchange.subscribe(
                     ExchangeEvents.LogCancel, indexFilterValues, callback,
                 );
                 await zeroEx.exchange.cancelOrderAsync(signedOrder, cancelTakerAmountInBaseUnits);
@@ -680,18 +686,18 @@ describe('ExchangeWrapper', () => {
                 const callbackNeverToBeCalled = (err: Error, logEvent: DecodedLogEvent<LogFillContractEventArgs>) => {
                     done(new Error('Expected this subscription to have been cancelled'));
                 };
-                await zeroEx.exchange.subscribeAsync(
+                zeroEx.exchange.subscribe(
                     ExchangeEvents.LogFill, indexFilterValues, callbackNeverToBeCalled,
                 );
 
                 const newProvider = web3Factory.getRpcProvider();
-                await zeroEx.setProviderAsync(newProvider);
+                zeroEx.setProvider(newProvider, constants.TESTRPC_NETWORK_ID);
 
                 const callback = (err: Error, logEvent: DecodedLogEvent<LogFillContractEventArgs>) => {
                     expect(logEvent.log.event).to.be.equal(ExchangeEvents.LogFill);
                     done();
                 };
-                await zeroEx.exchange.subscribeAsync(
+                zeroEx.exchange.subscribe(
                     ExchangeEvents.LogFill, indexFilterValues, callback,
                 );
                 await zeroEx.exchange.fillOrderAsync(
@@ -705,7 +711,7 @@ describe('ExchangeWrapper', () => {
                 const callbackNeverToBeCalled = (err: Error, logEvent: DecodedLogEvent<LogFillContractEventArgs>) => {
                     done(new Error('Expected this subscription to have been cancelled'));
                 };
-                const subscriptionToken = await zeroEx.exchange.subscribeAsync(
+                const subscriptionToken = zeroEx.exchange.subscribe(
                     ExchangeEvents.LogFill, indexFilterValues, callbackNeverToBeCalled,
                 );
                 zeroEx.exchange.unsubscribe(subscriptionToken);
@@ -740,8 +746,8 @@ describe('ExchangeWrapper', () => {
         });
     });
     describe('#getZRXTokenAddressAsync', () => {
-        it('gets the same token as is in token registry', async () => {
-            const zrxAddress = await zeroEx.exchange.getZRXTokenAddressAsync();
+        it('gets the same token as is in token registry', () => {
+            const zrxAddress = zeroEx.exchange.getZRXTokenAddress();
             const zrxToken = tokenUtils.getProtocolTokenOrThrow();
             expect(zrxAddress).to.equal(zrxToken.address);
         });
@@ -821,4 +827,4 @@ describe('ExchangeWrapper', () => {
             expect(args.maker).to.be.equal(differentMakerAddress);
         });
     });
-});
+}); // tslint:disable:max-file-line-count
diff --git a/packages/0x.js/test/expiration_watcher_test.ts b/packages/0x.js/test/expiration_watcher_test.ts
index 0f2470070..c60b5dc6c 100644
--- a/packages/0x.js/test/expiration_watcher_test.ts
+++ b/packages/0x.js/test/expiration_watcher_test.ts
@@ -1,20 +1,23 @@
-import 'mocha';
+import BigNumber from 'bignumber.js';
 import * as chai from 'chai';
 import * as _ from 'lodash';
+import 'mocha';
 import * as Sinon from 'sinon';
 import * as Web3 from 'web3';
-import BigNumber from 'bignumber.js';
-import {chaiSetup} from './utils/chai_setup';
-import {web3Factory} from './utils/web3_factory';
+
+import {ZeroEx} from '../src/0x';
+import {ExpirationWatcher} from '../src/order_watcher/expiration_watcher';
+import {DoneCallback, Token} from '../src/types';
+import {constants} from '../src/utils/constants';
 import {utils} from '../src/utils/utils';
 import {Web3Wrapper} from '../src/web3_wrapper';
-import {TokenUtils} from './utils/token_utils';
-import {ExpirationWatcher} from '../src/order_watcher/expiration_watcher';
-import {Token, DoneCallback} from '../src/types';
-import {ZeroEx} from '../src/0x';
+
 import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
+import {chaiSetup} from './utils/chai_setup';
 import {FillScenarios} from './utils/fill_scenarios';
 import {reportCallbackErrors} from './utils/report_callback_errors';
+import {TokenUtils} from './utils/token_utils';
+import {web3Factory} from './utils/web3_factory';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -41,8 +44,11 @@ describe('ExpirationWatcher', () => {
     let expirationWatcher: ExpirationWatcher;
     before(async () => {
         web3 = web3Factory.create();
-        zeroEx = new ZeroEx(web3.currentProvider);
-        exchangeContractAddress = await zeroEx.exchange.getContractAddressAsync();
+        const config = {
+            networkId: constants.TESTRPC_NETWORK_ID,
+        };
+        zeroEx = new ZeroEx(web3.currentProvider, config);
+        exchangeContractAddress = zeroEx.exchange.getContractAddress();
         userAddresses = await zeroEx.getAvailableAddressesAsync();
         tokens = await zeroEx.tokenRegistry.getTokensAsync();
         tokenUtils = new TokenUtils(tokens);
diff --git a/packages/0x.js/test/order_state_watcher_test.ts b/packages/0x.js/test/order_state_watcher_test.ts
index e635071b8..1e5bc1a35 100644
--- a/packages/0x.js/test/order_state_watcher_test.ts
+++ b/packages/0x.js/test/order_state_watcher_test.ts
@@ -1,31 +1,33 @@
-import 'mocha';
+import BigNumber from 'bignumber.js';
 import * as chai from 'chai';
 import * as _ from 'lodash';
+import 'mocha';
 import * as Web3 from 'web3';
-import BigNumber from 'bignumber.js';
-import {chaiSetup} from './utils/chai_setup';
-import {web3Factory} from './utils/web3_factory';
-import {Web3Wrapper} from '../src/web3_wrapper';
-import {OrderStateWatcher} from '../src/order_watcher/order_state_watcher';
+
 import {
-    Token,
-    ZeroEx,
-    LogEvent,
     DecodedLogEvent,
-    ZeroExConfig,
+    ExchangeContractErrs,
+    LogEvent,
     OrderState,
+    OrderStateInvalid,
+    OrderStateValid,
     SignedOrder,
+    Token,
+    ZeroEx,
+    ZeroExConfig,
     ZeroExError,
-    OrderStateValid,
-    OrderStateInvalid,
-    ExchangeContractErrs,
 } from '../src';
-import {TokenUtils} from './utils/token_utils';
-import {FillScenarios} from './utils/fill_scenarios';
+import {OrderStateWatcher} from '../src/order_watcher/order_state_watcher';
 import {DoneCallback} from '../src/types';
+import {Web3Wrapper} from '../src/web3_wrapper';
+
 import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
+import {chaiSetup} from './utils/chai_setup';
+import {constants} from './utils/constants';
+import {FillScenarios} from './utils/fill_scenarios';
 import {reportCallbackErrors} from './utils/report_callback_errors';
-import {constants as constants} from './utils/constants';
+import {TokenUtils} from './utils/token_utils';
+import {web3Factory} from './utils/web3_factory';
 
 const TIMEOUT_MS = 150;
 
@@ -48,12 +50,15 @@ describe('OrderStateWatcher', () => {
     let taker: string;
     let web3Wrapper: Web3Wrapper;
     let signedOrder: SignedOrder;
+    const config = {
+        networkId: constants.TESTRPC_NETWORK_ID,
+    };
     const decimals = constants.ZRX_DECIMALS;
     const fillableAmount = ZeroEx.toBaseUnitAmount(new BigNumber(5), decimals);
     before(async () => {
         web3 = web3Factory.create();
-        zeroEx = new ZeroEx(web3.currentProvider);
-        exchangeContractAddress = await zeroEx.exchange.getContractAddressAsync();
+        zeroEx = new ZeroEx(web3.currentProvider, config);
+        exchangeContractAddress = zeroEx.exchange.getContractAddress();
         userAddresses = await zeroEx.getAvailableAddressesAsync();
         [, maker, taker] = userAddresses;
         tokens = await zeroEx.tokenRegistry.getTokensAsync();
@@ -75,13 +80,13 @@ describe('OrderStateWatcher', () => {
                 makerToken.address, takerToken.address, maker, taker, fillableAmount,
             );
             const orderHash = ZeroEx.getOrderHashHex(signedOrder);
-            await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+            zeroEx.orderStateWatcher.addOrder(signedOrder);
             expect((zeroEx.orderStateWatcher as any)._orderByOrderHash).to.include({
                 [orderHash]: signedOrder,
             });
             let dependentOrderHashes = (zeroEx.orderStateWatcher as any)._dependentOrderHashes;
             expect(dependentOrderHashes[signedOrder.maker][signedOrder.makerTokenAddress]).to.have.keys(orderHash);
-            await zeroEx.orderStateWatcher.removeOrderAsync(orderHash);
+            zeroEx.orderStateWatcher.removeOrder(orderHash);
             expect((zeroEx.orderStateWatcher as any)._orderByOrderHash).to.not.include({
                 [orderHash]: signedOrder,
             });
@@ -94,7 +99,7 @@ describe('OrderStateWatcher', () => {
             );
             const orderHash = ZeroEx.getOrderHashHex(signedOrder);
             const nonExistentOrderHash = `0x${orderHash.substr(2).split('').reverse().join('')}`;
-            await zeroEx.orderStateWatcher.removeOrderAsync(nonExistentOrderHash);
+            zeroEx.orderStateWatcher.removeOrder(nonExistentOrderHash);
         });
     });
     describe('#subscribe', async () => {
@@ -111,7 +116,7 @@ describe('OrderStateWatcher', () => {
         afterEach(async () => {
             zeroEx.orderStateWatcher.unsubscribe();
             const orderHash = ZeroEx.getOrderHashHex(signedOrder);
-            await zeroEx.orderStateWatcher.removeOrderAsync(orderHash);
+            zeroEx.orderStateWatcher.removeOrder(orderHash);
         });
         it('should emit orderStateInvalid when maker allowance set to 0 for watched order', (done: DoneCallback) => {
             (async () => {
@@ -119,7 +124,7 @@ describe('OrderStateWatcher', () => {
                     makerToken.address, takerToken.address, maker, taker, fillableAmount,
                 );
                 const orderHash = ZeroEx.getOrderHashHex(signedOrder);
-                await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                zeroEx.orderStateWatcher.addOrder(signedOrder);
                 const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                     expect(orderState.isValid).to.be.false();
                     const invalidOrderState = orderState as OrderStateInvalid;
@@ -137,7 +142,7 @@ describe('OrderStateWatcher', () => {
                     makerToken.address, takerToken.address, maker, taker, fillableAmount,
                 );
                 const orderHash = ZeroEx.getOrderHashHex(signedOrder);
-                await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                zeroEx.orderStateWatcher.addOrder(signedOrder);
                 const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                     throw new Error('OrderState callback fired for irrelevant order');
                 });
@@ -158,7 +163,7 @@ describe('OrderStateWatcher', () => {
                     makerToken.address, takerToken.address, maker, taker, fillableAmount,
                 );
                 const orderHash = ZeroEx.getOrderHashHex(signedOrder);
-                await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                zeroEx.orderStateWatcher.addOrder(signedOrder);
                 const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                     expect(orderState.isValid).to.be.false();
                     const invalidOrderState = orderState as OrderStateInvalid;
@@ -178,7 +183,7 @@ describe('OrderStateWatcher', () => {
                     makerToken.address, takerToken.address, maker, taker, fillableAmount,
                 );
                 const orderHash = ZeroEx.getOrderHashHex(signedOrder);
-                await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                zeroEx.orderStateWatcher.addOrder(signedOrder);
 
                 const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                     expect(orderState.isValid).to.be.false();
@@ -206,7 +211,7 @@ describe('OrderStateWatcher', () => {
 
                 const fillAmountInBaseUnits = new BigNumber(2);
                 const orderHash = ZeroEx.getOrderHashHex(signedOrder);
-                await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                zeroEx.orderStateWatcher.addOrder(signedOrder);
 
                 const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                     expect(orderState.isValid).to.be.true();
@@ -237,7 +242,7 @@ describe('OrderStateWatcher', () => {
                     makerToken.address, takerToken.address, makerFee, takerFee, maker, taker, fillableAmount,
                     taker);
                 const orderHash = ZeroEx.getOrderHashHex(signedOrder);
-                await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                zeroEx.orderStateWatcher.addOrder(signedOrder);
                 const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                     done();
                 });
@@ -258,7 +263,7 @@ describe('OrderStateWatcher', () => {
                     const takerBalance = await zeroEx.token.getBalanceAsync(makerToken.address, taker);
                     const fillAmountInBaseUnits = ZeroEx.toBaseUnitAmount(new BigNumber(2), decimals);
                     const orderHash = ZeroEx.getOrderHashHex(signedOrder);
-                    await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                    zeroEx.orderStateWatcher.addOrder(signedOrder);
                     const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                         expect(orderState.isValid).to.be.true();
                         const validOrderState = orderState as OrderStateValid;
@@ -286,7 +291,7 @@ describe('OrderStateWatcher', () => {
                     const makerBalance = await zeroEx.token.getBalanceAsync(makerToken.address, maker);
 
                     const changedMakerApprovalAmount = ZeroEx.toBaseUnitAmount(new BigNumber(3), decimals);
-                    await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                    zeroEx.orderStateWatcher.addOrder(signedOrder);
 
                     const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                         const validOrderState = orderState as OrderStateValid;
@@ -311,7 +316,7 @@ describe('OrderStateWatcher', () => {
 
                     const remainingAmount = ZeroEx.toBaseUnitAmount(new BigNumber(1), decimals);
                     const transferAmount = makerBalance.sub(remainingAmount);
-                    await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                    zeroEx.orderStateWatcher.addOrder(signedOrder);
 
                     const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                         expect(orderState.isValid).to.be.true();
@@ -341,7 +346,7 @@ describe('OrderStateWatcher', () => {
 
                     const remainingTokenAmount = ZeroEx.toBaseUnitAmount(new BigNumber(4), decimals);
                     const transferTokenAmount = makerFee.sub(remainingTokenAmount);
-                    await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                    zeroEx.orderStateWatcher.addOrder(signedOrder);
 
                     const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                         expect(orderState.isValid).to.be.true();
@@ -371,7 +376,7 @@ describe('OrderStateWatcher', () => {
 
                     const remainingTokenAmount = ZeroEx.toBaseUnitAmount(new BigNumber(4), decimals);
                     const transferTokenAmount = makerFee.sub(remainingTokenAmount);
-                    await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                    zeroEx.orderStateWatcher.addOrder(signedOrder);
 
                     const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                         const validOrderState = orderState as OrderStateValid;
@@ -396,7 +401,7 @@ describe('OrderStateWatcher', () => {
                         taker, fillableAmount, feeRecipient);
 
                     const makerBalance = await zeroEx.token.getBalanceAsync(makerToken.address, maker);
-                    await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                    zeroEx.orderStateWatcher.addOrder(signedOrder);
 
                     const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                         const validOrderState = orderState as OrderStateValid;
@@ -417,7 +422,7 @@ describe('OrderStateWatcher', () => {
                     makerToken.address, takerToken.address, maker, taker, fillableAmount,
                 );
                 const orderHash = ZeroEx.getOrderHashHex(signedOrder);
-                await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                zeroEx.orderStateWatcher.addOrder(signedOrder);
 
                 const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                     expect(orderState.isValid).to.be.false();
@@ -439,7 +444,7 @@ describe('OrderStateWatcher', () => {
                     makerToken.address, takerToken.address, maker, taker, fillableAmount,
                 );
                 const orderHash = ZeroEx.getOrderHashHex(signedOrder);
-                await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                zeroEx.orderStateWatcher.addOrder(signedOrder);
 
                 const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                     expect(orderState.isValid).to.be.false();
@@ -465,7 +470,7 @@ describe('OrderStateWatcher', () => {
 
                 const cancelAmountInBaseUnits = new BigNumber(2);
                 const orderHash = ZeroEx.getOrderHashHex(signedOrder);
-                await zeroEx.orderStateWatcher.addOrderAsync(signedOrder);
+                zeroEx.orderStateWatcher.addOrder(signedOrder);
 
                 const callback = reportCallbackErrors(done)((orderState: OrderState) => {
                     expect(orderState.isValid).to.be.true();
@@ -480,4 +485,4 @@ describe('OrderStateWatcher', () => {
             })().catch(done);
         });
     });
-});
+}); // tslint:disable:max-file-line-count
diff --git a/packages/0x.js/test/order_validation_test.ts b/packages/0x.js/test/order_validation_test.ts
index d689ef073..d585c1f3c 100644
--- a/packages/0x.js/test/order_validation_test.ts
+++ b/packages/0x.js/test/order_validation_test.ts
@@ -1,16 +1,19 @@
-import * as chai from 'chai';
-import * as Web3 from 'web3';
 import BigNumber from 'bignumber.js';
+import * as chai from 'chai';
 import * as Sinon from 'sinon';
-import {chaiSetup} from './utils/chai_setup';
-import {web3Factory} from './utils/web3_factory';
-import {ZeroEx, SignedOrder, Token, ExchangeContractErrs, ZeroExError} from '../src';
-import {TradeSide, TransferType, BlockParamLiteral} from '../src/types';
-import {TokenUtils} from './utils/token_utils';
+import * as Web3 from 'web3';
+
+import {ExchangeContractErrs, SignedOrder, Token, ZeroEx, ZeroExError} from '../src';
+import {BlockParamLiteral, TradeSide, TransferType} from '../src/types';
+import {ExchangeTransferSimulator} from '../src/utils/exchange_transfer_simulator';
+import {OrderValidationUtils} from '../src/utils/order_validation_utils';
+
 import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
+import {chaiSetup} from './utils/chai_setup';
+import {constants} from './utils/constants';
 import {FillScenarios} from './utils/fill_scenarios';
-import {OrderValidationUtils} from '../src/utils/order_validation_utils';
-import {ExchangeTransferSimulator} from '../src/utils/exchange_transfer_simulator';
+import {TokenUtils} from './utils/token_utils';
+import {web3Factory} from './utils/web3_factory';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -34,10 +37,13 @@ describe('OrderValidation', () => {
     let orderValidationUtils: OrderValidationUtils;
     const fillableAmount = new BigNumber(5);
     const fillTakerAmount = new BigNumber(5);
+    const config = {
+        networkId: constants.TESTRPC_NETWORK_ID,
+    };
     before(async () => {
         web3 = web3Factory.create();
-        zeroEx = new ZeroEx(web3.currentProvider);
-        exchangeContractAddress = await zeroEx.exchange.getContractAddressAsync();
+        zeroEx = new ZeroEx(web3.currentProvider, config);
+        exchangeContractAddress = zeroEx.exchange.getContractAddress();
         userAddresses = await zeroEx.getAvailableAddressesAsync();
         [coinbase, makerAddress, takerAddress, feeRecipient] = userAddresses;
         tokens = await zeroEx.tokenRegistry.getTokensAsync();
@@ -110,7 +116,7 @@ describe('OrderValidation', () => {
                 makerTokenAddress, takerTokenAddress, makerAddress, takerAddress, fillableAmount,
             );
             // 27 <--> 28
-            signedOrder.ecSignature.v = 27 + (28 - signedOrder.ecSignature.v);
+            signedOrder.ecSignature.v = (28 - signedOrder.ecSignature.v) + 27;
             return expect(zeroEx.exchange.validateFillOrderThrowIfInvalidAsync(
                 signedOrder, fillableAmount, takerAddress,
             )).to.be.rejectedWith(ZeroExError.InvalidSignature);
@@ -226,7 +232,7 @@ describe('OrderValidation', () => {
                 makerTokenAddress, takerTokenAddress, makerFee, takerFee,
                 makerAddress, takerAddress, fillableAmount, feeRecipient,
             );
-            await orderValidationUtils.validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
+            await OrderValidationUtils.validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
                 exchangeTransferSimulator, signedOrder, fillableAmount, takerAddress, zrxTokenAddress,
             );
             expect(transferFromAsync.callCount).to.be.equal(4);
@@ -262,7 +268,7 @@ describe('OrderValidation', () => {
                 makerTokenAddress, takerTokenAddress, makerFee, takerFee,
                 makerAddress, ZeroEx.NULL_ADDRESS, fillableAmount, feeRecipient,
             );
-            await orderValidationUtils.validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
+            await OrderValidationUtils.validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
                 exchangeTransferSimulator, signedOrder, fillableAmount, takerAddress, zrxTokenAddress,
             );
             expect(transferFromAsync.callCount).to.be.equal(4);
@@ -297,7 +303,7 @@ describe('OrderValidation', () => {
             const signedOrder = await fillScenarios.createAsymmetricFillableSignedOrderAsync(
                 makerTokenAddress, takerTokenAddress, makerAddress, takerAddress, makerTokenAmount, takerTokenAmount,
             );
-            await orderValidationUtils.validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
+            await OrderValidationUtils.validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
                 exchangeTransferSimulator, signedOrder, takerTokenAmount, takerAddress, zrxTokenAddress,
             );
             expect(transferFromAsync.callCount).to.be.equal(4);
@@ -312,7 +318,7 @@ describe('OrderValidation', () => {
                 fillableAmount, ZeroEx.NULL_ADDRESS,
             );
             const fillTakerTokenAmount = fillableAmount.div(2).round(0);
-            await orderValidationUtils.validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
+            await OrderValidationUtils.validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
                 exchangeTransferSimulator, signedOrder, fillTakerTokenAmount, takerAddress, zrxTokenAddress,
             );
             const makerPartialFee = makerFee.div(2);
diff --git a/packages/0x.js/test/remaining_fillable_calculator_test.ts b/packages/0x.js/test/remaining_fillable_calculator_test.ts
index 65b65efd8..610bf9b1a 100644
--- a/packages/0x.js/test/remaining_fillable_calculator_test.ts
+++ b/packages/0x.js/test/remaining_fillable_calculator_test.ts
@@ -1,11 +1,13 @@
-import 'mocha';
-import * as chai from 'chai';
 import BigNumber from 'bignumber.js';
-import { chaiSetup } from './utils/chai_setup';
+import * as chai from 'chai';
+import 'mocha';
+
+import { ZeroEx } from '../src/0x';
 import { RemainingFillableCalculator } from '../src/order_watcher/remaining_fillable_calculator';
-import { SignedOrder, ECSignature } from '../src/types';
+import { ECSignature, SignedOrder } from '../src/types';
+
+import { chaiSetup } from './utils/chai_setup';
 import { TokenUtils } from './utils/token_utils';
-import { ZeroEx } from '../src/0x';
 
 chaiSetup.configure();
 const expect = chai.expect;
diff --git a/packages/0x.js/test/subscription_test.ts b/packages/0x.js/test/subscription_test.ts
index f69ae0b13..e3b15808b 100644
--- a/packages/0x.js/test/subscription_test.ts
+++ b/packages/0x.js/test/subscription_test.ts
@@ -1,23 +1,27 @@
-import 'mocha';
-import * as _ from 'lodash';
+import BigNumber from 'bignumber.js';
 import * as chai from 'chai';
+import promisify = require('es6-promisify');
+import * as _ from 'lodash';
+import 'mocha';
 import * as Sinon from 'sinon';
-import {chaiSetup} from './utils/chai_setup';
 import * as Web3 from 'web3';
-import BigNumber from 'bignumber.js';
-import promisify = require('es6-promisify');
-import {web3Factory} from './utils/web3_factory';
+
 import {
-    ZeroEx,
-    ZeroExError,
-    Token,
     ApprovalContractEventArgs,
-    TokenEvents,
     DecodedLogEvent,
+    Token,
+    TokenEvents,
+    ZeroEx,
+    ZeroExError,
 } from '../src';
+import {BlockParamLiteral, DoneCallback} from '../src/types';
+
 import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
+import {chaiSetup} from './utils/chai_setup';
+import {constants} from './utils/constants';
+import {reportCallbackErrors} from './utils/report_callback_errors';
 import {TokenUtils} from './utils/token_utils';
-import {DoneCallback, BlockParamLiteral} from '../src/types';
+import {web3Factory} from './utils/web3_factory';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -31,9 +35,12 @@ describe('SubscriptionTest', () => {
     let tokenUtils: TokenUtils;
     let coinbase: string;
     let addressWithoutFunds: string;
+    const config = {
+        networkId: constants.TESTRPC_NETWORK_ID,
+    };
     before(async () => {
         web3 = web3Factory.create();
-        zeroEx = new ZeroEx(web3.currentProvider);
+        zeroEx = new ZeroEx(web3.currentProvider, config);
         userAddresses = await zeroEx.getAvailableAddressesAsync();
         tokens = await zeroEx.tokenRegistry.getTokensAsync();
         tokenUtils = new TokenUtils(tokens);
@@ -62,22 +69,44 @@ describe('SubscriptionTest', () => {
             _.each(stubs, s => s.restore());
             stubs = [];
         });
-        it('Should receive the Error when an error occurs', (done: DoneCallback) => {
+        it('Should receive the Error when an error occurs while fetching the block', (done: DoneCallback) => {
             (async () => {
-                const callback = (err: Error, logEvent: DecodedLogEvent<ApprovalContractEventArgs>) => {
-                    expect(err).to.not.be.null();
-                    expect(logEvent).to.be.undefined();
-                    done();
-                };
+                const errMsg = 'Error fetching block';
+                const callback = reportCallbackErrors(done)(
+                    (err: Error, logEvent: DecodedLogEvent<ApprovalContractEventArgs>) => {
+                        expect(err.message).to.be.equal(errMsg);
+                        expect(logEvent).to.be.undefined();
+                        done();
+                    },
+                );
                 stubs = [
                   Sinon.stub((zeroEx as any)._web3Wrapper, 'getBlockAsync')
-                   .throws('JSON RPC error'),
+                   .throws(new Error(errMsg)),
+                ];
+                zeroEx.token.subscribe(
+                    tokenAddress, TokenEvents.Approval, indexFilterValues, callback);
+                await zeroEx.token.setAllowanceAsync(tokenAddress, coinbase, addressWithoutFunds, allowanceAmount);
+            })().catch(done);
+        });
+        it('Should receive the Error when an error occurs while reconciling the new block', (done: DoneCallback) => {
+            (async () => {
+                const errMsg = 'Error fetching logs';
+                const callback = reportCallbackErrors(done)(
+                    (err: Error, logEvent: DecodedLogEvent<ApprovalContractEventArgs>) => {
+                        expect(err.message).to.be.equal(errMsg);
+                        expect(logEvent).to.be.undefined();
+                        done();
+                    },
+                );
+                stubs = [
+                  Sinon.stub((zeroEx as any)._web3Wrapper, 'getLogsAsync')
+                   .throws(new Error(errMsg)),
                 ];
                 zeroEx.token.subscribe(
                     tokenAddress, TokenEvents.Approval, indexFilterValues, callback);
                 await zeroEx.token.setAllowanceAsync(tokenAddress, coinbase, addressWithoutFunds, allowanceAmount);
             })().catch(done);
-         });
+        });
         it('Should allow unsubscribeAll to be called successfully after an error', (done: DoneCallback) => {
             (async () => {
                 const callback = (err: Error, logEvent: DecodedLogEvent<ApprovalContractEventArgs>) => _.noop;
@@ -85,11 +114,11 @@ describe('SubscriptionTest', () => {
                     tokenAddress, TokenEvents.Approval, indexFilterValues, callback);
                 stubs = [
                   Sinon.stub((zeroEx as any)._web3Wrapper, 'getBlockAsync')
-                   .throws('JSON RPC error'),
+                   .throws(new Error('JSON RPC error')),
                 ];
                 zeroEx.token.unsubscribeAll();
                 done();
             })().catch(done);
-         });
+        });
     });
 });
diff --git a/packages/0x.js/test/token_registry_wrapper_test.ts b/packages/0x.js/test/token_registry_wrapper_test.ts
index d3497451b..f1f307f3a 100644
--- a/packages/0x.js/test/token_registry_wrapper_test.ts
+++ b/packages/0x.js/test/token_registry_wrapper_test.ts
@@ -1,11 +1,14 @@
+import {schemas, SchemaValidator} from '@0xproject/json-schemas';
+import * as chai from 'chai';
 import * as _ from 'lodash';
 import 'mocha';
-import * as chai from 'chai';
-import {SchemaValidator, schemas} from '@0xproject/json-schemas';
+
+import {Token, ZeroEx} from '../src';
+
+import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
 import {chaiSetup} from './utils/chai_setup';
+import {constants} from './utils/constants';
 import {web3Factory} from './utils/web3_factory';
-import {ZeroEx, Token} from '../src';
-import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -24,9 +27,12 @@ describe('TokenRegistryWrapper', () => {
     const registeredName = '0x Protocol Token';
     const unregisteredSymbol = 'MAL';
     const unregisteredName = 'Malicious Token';
+    const config = {
+        networkId: constants.TESTRPC_NETWORK_ID,
+    };
     before(async () => {
         const web3 = web3Factory.create();
-        zeroEx = new ZeroEx(web3.currentProvider);
+        zeroEx = new ZeroEx(web3.currentProvider, config);
         tokens = await zeroEx.tokenRegistry.getTokensAsync();
         _.map(tokens, token => {
             tokenAddressBySymbol[token.symbol] = token.address;
diff --git a/packages/0x.js/test/token_transfer_proxy_wrapper_test.ts b/packages/0x.js/test/token_transfer_proxy_wrapper_test.ts
index 8faef0b30..05861d112 100644
--- a/packages/0x.js/test/token_transfer_proxy_wrapper_test.ts
+++ b/packages/0x.js/test/token_transfer_proxy_wrapper_test.ts
@@ -1,17 +1,23 @@
 import * as chai from 'chai';
-import {chaiSetup} from './utils/chai_setup';
-import {web3Factory} from './utils/web3_factory';
+
 import {ZeroEx} from '../src';
 import {TokenTransferProxyWrapper} from '../src/contract_wrappers/token_transfer_proxy_wrapper';
 
+import {chaiSetup} from './utils/chai_setup';
+import {constants} from './utils/constants';
+import {web3Factory} from './utils/web3_factory';
+
 chaiSetup.configure();
 const expect = chai.expect;
 
 describe('TokenTransferProxyWrapper', () => {
     let zeroEx: ZeroEx;
+    const config = {
+        networkId: constants.TESTRPC_NETWORK_ID,
+    };
     before(async () => {
         const web3 = web3Factory.create();
-        zeroEx = new ZeroEx(web3.currentProvider);
+        zeroEx = new ZeroEx(web3.currentProvider, config);
     });
     describe('#isAuthorizedAsync', () => {
         it('should return false if the address is not authorized', async () => {
diff --git a/packages/0x.js/test/token_wrapper_test.ts b/packages/0x.js/test/token_wrapper_test.ts
index b3c8edcc4..cc61c2324 100644
--- a/packages/0x.js/test/token_wrapper_test.ts
+++ b/packages/0x.js/test/token_wrapper_test.ts
@@ -1,27 +1,30 @@
-import 'mocha';
-import * as chai from 'chai';
-import {chaiSetup} from './utils/chai_setup';
-import * as Web3 from 'web3';
 import BigNumber from 'bignumber.js';
+import * as chai from 'chai';
 import promisify = require('es6-promisify');
-import {web3Factory} from './utils/web3_factory';
+import 'mocha';
+import * as Web3 from 'web3';
+
 import {
-    ZeroEx,
-    ZeroExError,
-    Token,
+    ApprovalContractEventArgs,
+    ContractEvent,
+    DecodedLogEvent,
+    LogEvent,
+    LogWithDecodedArgs,
     SubscriptionOpts,
+    Token,
+    TokenContractEventArgs,
     TokenEvents,
-    ContractEvent,
     TransferContractEventArgs,
-    ApprovalContractEventArgs,
-    TokenContractEventArgs,
-    LogWithDecodedArgs,
-    LogEvent,
-    DecodedLogEvent,
+    ZeroEx,
+    ZeroExError,
 } from '../src';
+import {BlockParamLiteral, DoneCallback} from '../src/types';
+
 import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
+import {chaiSetup} from './utils/chai_setup';
+import {constants} from './utils/constants';
 import {TokenUtils} from './utils/token_utils';
-import {DoneCallback, BlockParamLiteral} from '../src/types';
+import {web3Factory} from './utils/web3_factory';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -35,9 +38,12 @@ describe('TokenWrapper', () => {
     let tokenUtils: TokenUtils;
     let coinbase: string;
     let addressWithoutFunds: string;
+    const config = {
+        networkId: constants.TESTRPC_NETWORK_ID,
+    };
     before(async () => {
         web3 = web3Factory.create();
-        zeroEx = new ZeroEx(web3.currentProvider);
+        zeroEx = new ZeroEx(web3.currentProvider, config);
         userAddresses = await zeroEx.getAvailableAddressesAsync();
         tokens = await zeroEx.tokenRegistry.getTokensAsync();
         tokenUtils = new TokenUtils(tokens);
@@ -80,7 +86,7 @@ describe('TokenWrapper', () => {
             const toAddress = coinbase;
             return expect(zeroEx.token.transferAsync(
                 nonExistentTokenAddress, fromAddress, toAddress, transferAmount,
-            )).to.be.rejectedWith(ZeroExError.ContractDoesNotExist);
+            )).to.be.rejectedWith(ZeroExError.TokenContractDoesNotExist);
         });
     });
     describe('#transferFromAsync', () => {
@@ -153,7 +159,7 @@ describe('TokenWrapper', () => {
             const nonExistentTokenAddress = '0x9dd402f14d67e001d8efbe6583e51bf9706aa065';
             return expect(zeroEx.token.transferFromAsync(
                 nonExistentTokenAddress, fromAddress, toAddress, senderAddress, new BigNumber(42),
-            )).to.be.rejectedWith(ZeroExError.ContractDoesNotExist);
+            )).to.be.rejectedWith(ZeroExError.TokenContractDoesNotExist);
         });
     });
     describe('#getBalanceAsync', () => {
@@ -169,7 +175,7 @@ describe('TokenWrapper', () => {
                 const nonExistentTokenAddress = '0x9dd402f14d67e001d8efbe6583e51bf9706aa065';
                 const ownerAddress = coinbase;
                 return expect(zeroEx.token.getBalanceAsync(nonExistentTokenAddress, ownerAddress))
-                    .to.be.rejectedWith(ZeroExError.ContractDoesNotExist);
+                    .to.be.rejectedWith(ZeroExError.TokenContractDoesNotExist);
             });
             it('should return a balance of 0 for a non-existent owner address', async () => {
                 const token = tokens[0];
@@ -184,7 +190,7 @@ describe('TokenWrapper', () => {
             before(async () => {
                 const hasAddresses = false;
                 const web3WithoutAccounts = web3Factory.create(hasAddresses);
-                zeroExWithoutAccounts = new ZeroEx(web3WithoutAccounts.currentProvider);
+                zeroExWithoutAccounts = new ZeroEx(web3WithoutAccounts.currentProvider, config);
             });
             it('should return balance even when called with Web3 provider instance without addresses', async () => {
                     const token = tokens[0];
@@ -281,7 +287,7 @@ describe('TokenWrapper', () => {
             before(async () => {
                 const hasAddresses = false;
                 const web3WithoutAccounts = web3Factory.create(hasAddresses);
-                zeroExWithoutAccounts = new ZeroEx(web3WithoutAccounts.currentProvider);
+                zeroExWithoutAccounts = new ZeroEx(web3WithoutAccounts.currentProvider, config);
             });
             it('should get the proxy allowance', async () => {
                 const token = tokens[0];
@@ -404,7 +410,7 @@ describe('TokenWrapper', () => {
                     done();
                 };
                 const newProvider = web3Factory.getRpcProvider();
-                await zeroEx.setProviderAsync(newProvider);
+                zeroEx.setProvider(newProvider, constants.TESTRPC_NETWORK_ID);
                 zeroEx.token.subscribe(
                     tokenAddress, TokenEvents.Transfer, indexFilterValues, callbackToBeCalled,
                 );
@@ -432,10 +438,10 @@ describe('TokenWrapper', () => {
             toBlock: BlockParamLiteral.Latest,
         };
         let txHash: string;
-        before(async () => {
+        before(() => {
             const token = tokens[0];
             tokenAddress = token.address;
-            tokenTransferProxyAddress = await zeroEx.proxy.getContractAddressAsync();
+            tokenTransferProxyAddress = zeroEx.proxy.getContractAddress();
         });
         it('should get logs with decoded args emitted by Approval', async () => {
             txHash = await zeroEx.token.setUnlimitedProxyAllowanceAsync(tokenAddress, coinbase);
diff --git a/packages/0x.js/test/utils/chai_setup.ts b/packages/0x.js/test/utils/chai_setup.ts
index c18988106..078edd309 100644
--- a/packages/0x.js/test/utils/chai_setup.ts
+++ b/packages/0x.js/test/utils/chai_setup.ts
@@ -1,7 +1,7 @@
 import * as chai from 'chai';
-import * as dirtyChai from 'dirty-chai';
-import ChaiBigNumber = require('chai-bignumber');
 import chaiAsPromised = require('chai-as-promised');
+import ChaiBigNumber = require('chai-bignumber');
+import * as dirtyChai from 'dirty-chai';
 
 export const chaiSetup = {
     configure() {
diff --git a/packages/0x.js/test/utils/constants.ts b/packages/0x.js/test/utils/constants.ts
index 5992c226e..212abf4d6 100644
--- a/packages/0x.js/test/utils/constants.ts
+++ b/packages/0x.js/test/utils/constants.ts
@@ -2,6 +2,8 @@ export const constants = {
     NULL_ADDRESS: '0x0000000000000000000000000000000000000000',
     RPC_HOST: 'localhost',
     RPC_PORT: 8545,
+    ROPSTEN_NETWORK_ID: 3,
+    KOVAN_NETWORK_ID: 42,
     TESTRPC_NETWORK_ID: 50,
     KOVAN_RPC_URL: 'https://kovan.infura.io',
     ROPSTEN_RPC_URL: 'https://ropsten.infura.io',
diff --git a/packages/0x.js/test/utils/fill_scenarios.ts b/packages/0x.js/test/utils/fill_scenarios.ts
index a0632b12c..090493935 100644
--- a/packages/0x.js/test/utils/fill_scenarios.ts
+++ b/packages/0x.js/test/utils/fill_scenarios.ts
@@ -1,6 +1,8 @@
 import BigNumber from 'bignumber.js';
-import {ZeroEx, Token, SignedOrder} from '../../src';
+
+import {SignedOrder, Token, ZeroEx} from '../../src';
 import {orderFactory} from '../utils/order_factory';
+
 import {constants} from './constants';
 
 export class FillScenarios {
diff --git a/packages/0x.js/test/utils/order_factory.ts b/packages/0x.js/test/utils/order_factory.ts
index 6086e09f7..41d93e340 100644
--- a/packages/0x.js/test/utils/order_factory.ts
+++ b/packages/0x.js/test/utils/order_factory.ts
@@ -1,6 +1,7 @@
-import * as _ from 'lodash';
 import BigNumber from 'bignumber.js';
-import {ZeroEx, SignedOrder} from '../../src';
+import * as _ from 'lodash';
+
+import {SignedOrder, ZeroEx} from '../../src';
 
 export const orderFactory = {
     async createSignedOrderAsync(
@@ -15,11 +16,11 @@ export const orderFactory = {
         takerTokenAddress: string,
         exchangeContractAddress: string,
         feeRecipient: string,
-        expirationUnixTimestampSec?: BigNumber): Promise<SignedOrder> {
+        expirationUnixTimestampSecIfExists?: BigNumber): Promise<SignedOrder> {
         const defaultExpirationUnixTimestampSec = new BigNumber(2524604400); // Close to infinite
-        expirationUnixTimestampSec = _.isUndefined(expirationUnixTimestampSec) ?
+        const expirationUnixTimestampSec = _.isUndefined(expirationUnixTimestampSecIfExists) ?
             defaultExpirationUnixTimestampSec :
-            expirationUnixTimestampSec;
+            expirationUnixTimestampSecIfExists;
         const order = {
             maker,
             taker,
diff --git a/packages/0x.js/test/utils/report_callback_errors.ts b/packages/0x.js/test/utils/report_callback_errors.ts
index 4f9517704..8a8f4d966 100644
--- a/packages/0x.js/test/utils/report_callback_errors.ts
+++ b/packages/0x.js/test/utils/report_callback_errors.ts
@@ -1,10 +1,10 @@
 import { DoneCallback } from '../../src/types';
 
 export const reportCallbackErrors = (done: DoneCallback) => {
-    return (fAsync: (...args: any[]) => void|Promise<void>) => {
+    return (f: (...args: any[]) => void) => {
         const wrapped = async (...args: any[]) => {
             try {
-                await fAsync(...args);
+                f(...args);
             } catch (err) {
                 done(err);
             }
diff --git a/packages/0x.js/test/utils/rpc.ts b/packages/0x.js/test/utils/rpc.ts
index 299e72e79..309a96d5e 100644
--- a/packages/0x.js/test/utils/rpc.ts
+++ b/packages/0x.js/test/utils/rpc.ts
@@ -1,5 +1,6 @@
 import * as ethUtil from 'ethereumjs-util';
 import * as request from 'request-promise-native';
+
 import {constants} from './constants';
 
 export class RPC {
diff --git a/packages/0x.js/test/utils/token_utils.ts b/packages/0x.js/test/utils/token_utils.ts
index 51cb9411c..9c20f52a1 100644
--- a/packages/0x.js/test/utils/token_utils.ts
+++ b/packages/0x.js/test/utils/token_utils.ts
@@ -1,5 +1,6 @@
 import * as _ from 'lodash';
-import {Token, InternalZeroExError} from '../../src/types';
+
+import {InternalZeroExError, Token} from '../../src/types';
 
 const PROTOCOL_TOKEN_SYMBOL = 'ZRX';
 
diff --git a/packages/0x.js/test/utils/web3_factory.ts b/packages/0x.js/test/utils/web3_factory.ts
index b20070c74..b4bf1acd3 100644
--- a/packages/0x.js/test/utils/web3_factory.ts
+++ b/packages/0x.js/test/utils/web3_factory.ts
@@ -3,12 +3,14 @@
 // we are not running in a browser env.
 // Filed issue: https://github.com/ethereum/web3.js/issues/844
 (global as any).XMLHttpRequest = undefined;
+import * as Web3 from 'web3';
 import ProviderEngine = require('web3-provider-engine');
 import RpcSubprovider = require('web3-provider-engine/subproviders/rpc');
-import * as Web3 from 'web3';
-import {constants} from './constants';
+
 import {EmptyWalletSubProvider} from '../../src/subproviders/empty_wallet_subprovider';
 
+import {constants} from './constants';
+
 export const web3Factory = {
     create(hasAddresses: boolean = true): Web3 {
         const provider = this.getRpcProvider(hasAddresses);
diff --git a/packages/0x.js/test/web3_wrapper_test.ts b/packages/0x.js/test/web3_wrapper_test.ts
deleted file mode 100644
index d1c2e8e89..000000000
--- a/packages/0x.js/test/web3_wrapper_test.ts
+++ /dev/null
@@ -1,29 +0,0 @@
-import * as chai from 'chai';
-import {web3Factory} from './utils/web3_factory';
-import {ZeroEx} from '../src/';
-import {Web3Wrapper} from '../src/web3_wrapper';
-import {constants} from './utils/constants';
-
-chai.config.includeStack = true;
-const expect = chai.expect;
-
-describe('Web3Wrapper', () => {
-    const web3Provider = web3Factory.create().currentProvider;
-    describe('#getNetworkIdIfExistsAsync', () => {
-        it('caches network id requests', async () => {
-            const web3Wrapper = (new ZeroEx(web3Provider) as any)._web3Wrapper as Web3Wrapper;
-            expect((web3Wrapper as any).networkIdIfExists).to.be.undefined();
-            const networkIdIfExists = await web3Wrapper.getNetworkIdIfExistsAsync();
-            expect((web3Wrapper as any).networkIdIfExists).to.be.equal(constants.TESTRPC_NETWORK_ID);
-        });
-        it('invalidates network id cache on setProvider call', async () => {
-            const web3Wrapper = (new ZeroEx(web3Provider) as any)._web3Wrapper as Web3Wrapper;
-            expect((web3Wrapper as any).networkIdIfExists).to.be.undefined();
-            const networkIdIfExists = await web3Wrapper.getNetworkIdIfExistsAsync();
-            expect((web3Wrapper as any).networkIdIfExists).to.be.equal(constants.TESTRPC_NETWORK_ID);
-            const newProvider = web3Factory.create().currentProvider;
-            web3Wrapper.setProvider(newProvider);
-            expect((web3Wrapper as any).networkIdIfExists).to.be.undefined();
-        });
-    });
-});