Refactor event scraping and add support for scraping ERC20 approval events (#1401)

* Refactor event scraping and add support for scraping ERC20 approval events

* Add tests for data_sources/contract-wrappers/utils

3 files changed, 55 insertions, 2 deletions

diff --git a/packages/pipeline/test/parsers/bloxy/index_test.ts b/packages/pipeline/test/parsers/bloxy/index_test.ts
index 2b8d68f98..6aabb091d 100644
--- a/packages/pipeline/test/parsers/bloxy/index_test.ts
+++ b/packages/pipeline/test/parsers/bloxy/index_test.ts
@@ -7,7 +7,6 @@ import * as R from 'ramda';
 import { BLOXY_DEX_TRADES_URL, BloxyTrade } from '../../../src/data_sources/bloxy';
 import { DexTrade } from '../../../src/entities';
 import { _parseBloxyTrade } from '../../../src/parsers/bloxy';
-import { _convertToExchangeFillEvent } from '../../../src/parsers/events';
 import { chaiSetup } from '../../utils/chai_setup';
 
 chaiSetup.configure();
diff --git a/packages/pipeline/test/parsers/events/erc20_events_test.ts b/packages/pipeline/test/parsers/events/erc20_events_test.ts
new file mode 100644
index 000000000..962c50f98
--- /dev/null
+++ b/packages/pipeline/test/parsers/events/erc20_events_test.ts
@@ -0,0 +1,54 @@
+import { ERC20TokenApprovalEventArgs } from '@0x/contract-wrappers';
+import { BigNumber } from '@0x/utils';
+import * as chai from 'chai';
+import { LogWithDecodedArgs } from 'ethereum-types';
+import 'mocha';
+
+import { ERC20ApprovalEvent } from '../../../src/entities';
+import { _convertToERC20ApprovalEvent } from '../../../src/parsers/events/erc20_events';
+import { _convertToExchangeFillEvent } from '../../../src/parsers/events/exchange_events';
+import { chaiSetup } from '../../utils/chai_setup';
+
+chaiSetup.configure();
+const expect = chai.expect;
+
+// tslint:disable:custom-no-magic-numbers
+describe('erc20_events', () => {
+    describe('_convertToERC20ApprovalEvent', () => {
+        it('converts LogWithDecodedArgs to ERC20ApprovalEvent entity', () => {
+            const input: LogWithDecodedArgs<ERC20TokenApprovalEventArgs> = {
+                address: '0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2',
+                blockHash: '0xd2d7aafaa7102aec0bca8ef026d5a85133e87892334c46ee1e92e42912991c9b',
+                blockNumber: 6281577,
+                data: '0x000000000000000000000000000000000000000000000002b9cba5ee21ad3df9',
+                logIndex: 43,
+                topics: [
+                    '0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925',
+                    '0x0000000000000000000000000b65c5f6f3a05d6be5588a72b603360773b3fe04',
+                    '0x000000000000000000000000448a5065aebb8e423f0896e6c5d525c040f59af3',
+                ],
+                transactionHash: '0xcb46b19c786376a0a0140d51e3e606a4c4f926d8ca5434e96d2f69d04d8d9c7f',
+                transactionIndex: 103,
+                event: 'Approval',
+                args: {
+                    _owner: '0x0b65c5f6f3a05d6be5588a72b603360773b3fe04',
+                    _spender: '0x448a5065aebb8e423f0896e6c5d525c040f59af3',
+                    _value: new BigNumber('50281464906893835769'),
+                },
+            };
+
+            const expected = new ERC20ApprovalEvent();
+            expected.tokenAddress = '0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2';
+            expected.blockNumber = 6281577;
+            expected.rawData = '0x000000000000000000000000000000000000000000000002b9cba5ee21ad3df9';
+            expected.logIndex = 43;
+            expected.transactionHash = '0xcb46b19c786376a0a0140d51e3e606a4c4f926d8ca5434e96d2f69d04d8d9c7f';
+            expected.ownerAddress = '0x0b65c5f6f3a05d6be5588a72b603360773b3fe04';
+            expected.spenderAddress = '0x448a5065aebb8e423f0896e6c5d525c040f59af3';
+            expected.amount = new BigNumber('50281464906893835769');
+
+            const actual = _convertToERC20ApprovalEvent(input);
+            expect(actual).deep.equal(expected);
+        });
+    });
+});
diff --git a/packages/pipeline/test/parsers/events/index_test.ts b/packages/pipeline/test/parsers/events/exchange_events_test.ts
index 7e439ce39..5d4b185a5 100644
--- a/packages/pipeline/test/parsers/events/index_test.ts
+++ b/packages/pipeline/test/parsers/events/exchange_events_test.ts
@@ -5,7 +5,7 @@ import { LogWithDecodedArgs } from 'ethereum-types';
 import 'mocha';
 
 import { ExchangeFillEvent } from '../../../src/entities';
-import { _convertToExchangeFillEvent } from '../../../src/parsers/events';
+import { _convertToExchangeFillEvent } from '../../../src/parsers/events/exchange_events';
 import { chaiSetup } from '../../utils/chai_setup';
 
 chaiSetup.configure();