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

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

6 files changed, 154 insertions, 131 deletions

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;
-    }
 }