Make logs fetching and sunscriptions more type-safe

9 files changed, 80 insertions, 64 deletions

diff --git a/src/contract_wrappers/contract_wrapper.ts b/src/contract_wrappers/contract_wrapper.ts
index f6ccfdee4..19dccc6f2 100644
--- a/src/contract_wrappers/contract_wrapper.ts
+++ b/src/contract_wrappers/contract_wrapper.ts
@@ -14,6 +14,7 @@ import {
     IndexedFilterValues,
     EventCallback,
     BlockParamLiteral,
+    ContractEventArgs,
 } from '../types';
 import {constants} from '../utils/constants';
 import {intervalUtils} from '../utils/interval_utils';
@@ -25,7 +26,7 @@ export class ContractWrapper {
     private _blockAndLogStreamer: BlockAndLogStreamer|undefined;
     private _blockAndLogStreamInterval: NodeJS.Timer;
     private _filters: {[filterToken: string]: Web3.FilterObject};
-    private _filterCallbacks: {[filterToken: string]: EventCallback};
+    private _filterCallbacks: {[filterToken: string]: EventCallback<ContractEventArgs>};
     private _onLogAddedSubscriptionToken: string|undefined;
     private _onLogRemovedSubscriptionToken: string|undefined;
     constructor(web3Wrapper: Web3Wrapper, abiDecoder?: AbiDecoder) {
@@ -37,9 +38,9 @@ export class ContractWrapper {
         this._onLogAddedSubscriptionToken = undefined;
         this._onLogRemovedSubscriptionToken = undefined;
     }
-    protected _subscribe(address: string, eventName: ContractEvents,
-                         indexFilterValues: IndexedFilterValues, abi: Web3.ContractAbi,
-                         callback: EventCallback): string {
+    protected _subscribe<ArgsType extends ContractEventArgs>(
+        address: string, eventName: ContractEvents, indexFilterValues: IndexedFilterValues, abi: Web3.ContractAbi,
+        callback: EventCallback<ArgsType>): string {
         const filter = filterUtils.getFilter(address, eventName, indexFilterValues, abi);
         if (_.isUndefined(this._blockAndLogStreamer)) {
             this._startBlockAndLogStream();
@@ -59,32 +60,32 @@ export class ContractWrapper {
             this._stopBlockAndLogStream();
         }
     }
-    protected async _getLogsAsync(address: string, eventName: ContractEvents, subscriptionOpts: SubscriptionOpts,
-                                  indexFilterValues: IndexedFilterValues,
-                                  abi: Web3.ContractAbi): Promise<LogWithDecodedArgs[]> {
+    protected async _getLogsAsync<ArgsType extends ContractEventArgs>(
+        address: string, eventName: ContractEvents, subscriptionOpts: SubscriptionOpts,
+        indexFilterValues: IndexedFilterValues, abi: Web3.ContractAbi): Promise<Array<LogWithDecodedArgs<ArgsType>>> {
         const filter = filterUtils.getFilter(address, eventName, indexFilterValues, abi, subscriptionOpts);
         const logs = await this._web3Wrapper.getLogsAsync(filter);
         const logsWithDecodedArguments = _.map(logs, this._tryToDecodeLogOrNoop.bind(this));
         return logsWithDecodedArguments;
     }
-    protected _tryToDecodeLogOrNoop(log: Web3.LogEntry): LogWithDecodedArgs|RawLog {
+    protected _tryToDecodeLogOrNoop<ArgsType extends ContractEventArgs>(
+        log: Web3.LogEntry): LogWithDecodedArgs<ArgsType>|RawLog {
         if (_.isUndefined(this._abiDecoder)) {
             throw new Error(InternalZeroExError.NoAbiDecoder);
         }
         const logWithDecodedArgs = this._abiDecoder.tryToDecodeLogOrNoop(log);
         return logWithDecodedArgs;
     }
-    protected async _instantiateContractIfExistsAsync<A extends Web3.ContractInstance>(artifact: Artifact,
-                                                                                       addressIfExists?: string,
-                                                                                      ): Promise<A> {
+    protected async _instantiateContractIfExistsAsync<ContractType extends Web3.ContractInstance>(
+        artifact: Artifact, addressIfExists?: string): Promise<ContractType> {
         const contractInstance =
-            await this._web3Wrapper.getContractInstanceFromArtifactAsync<A>(artifact, addressIfExists);
+            await this._web3Wrapper.getContractInstanceFromArtifactAsync<ContractType>(artifact, addressIfExists);
         return contractInstance;
     }
-    private _onLogStateChanged(removed: boolean, log: Web3.LogEntry): void {
+    private _onLogStateChanged<ArgsType extends ContractEventArgs>(removed: boolean, log: Web3.LogEntry): void {
         _.forEach(this._filters, (filter: Web3.FilterObject, filterToken: string) => {
             if (filterUtils.matchesFilter(log, filter)) {
-                const decodedLog = this._tryToDecodeLogOrNoop(log) as LogWithDecodedArgs;
+                const decodedLog = this._tryToDecodeLogOrNoop(log) as LogWithDecodedArgs<ArgsType>;
                 const logEvent = {
                     ...decodedLog,
                     removed,
diff --git a/src/contract_wrappers/exchange_wrapper.ts b/src/contract_wrappers/exchange_wrapper.ts
index 9e4936de6..739fe74c6 100644
--- a/src/contract_wrappers/exchange_wrapper.ts
+++ b/src/contract_wrappers/exchange_wrapper.ts
@@ -1,4 +1,5 @@
 import * as _ from 'lodash';
+import * as Web3 from 'web3';
 import * as BigNumber from 'bignumber.js';
 import {schemas} from '0x-json-schemas';
 import {Web3Wrapper} from '../web3_wrapper';
@@ -28,6 +29,8 @@ import {
     OrderTransactionOpts,
     RawLog,
     EventCallback,
+    ExchangeContractEventArgs,
+    DecodedLogArgs,
 } from '../types';
 import {assert} from '../utils/assert';
 import {utils} from '../utils/utils';
@@ -654,13 +657,14 @@ 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(eventName: ExchangeEvents, indexFilterValues: IndexedFilterValues,
-                                callback: EventCallback): Promise<string> {
+    public async subscribeAsync<ArgsType extends ExchangeContractEventArgs>(
+        eventName: ExchangeEvents, indexFilterValues: IndexedFilterValues,
+        callback: EventCallback<ArgsType>): Promise<string> {
         assert.doesBelongToStringEnum('eventName', eventName, ExchangeEvents);
         assert.doesConformToSchema('indexFilterValues', indexFilterValues, schemas.indexFilterValuesSchema);
         assert.isFunction('callback', callback);
         const exchangeContractAddress = await this.getContractAddressAsync();
-        const subscriptionToken = this._subscribe(
+        const subscriptionToken = this._subscribe<ArgsType>(
             exchangeContractAddress, eventName, indexFilterValues, artifacts.ExchangeArtifact.abi, callback,
         );
         this._activeSubscriptions.push(subscriptionToken);
@@ -682,13 +686,14 @@ export class ExchangeWrapper extends ContractWrapper {
      *                              the value is the value you are interested in. E.g `{_from: aUserAddressHex}`
      * @return  Array of logs that match the parameters
      */
-    public async getLogsAsync(eventName: ExchangeEvents, subscriptionOpts: SubscriptionOpts,
-                              indexFilterValues: IndexedFilterValues): Promise<LogWithDecodedArgs[]> {
+    public async getLogsAsync<ArgsType extends ExchangeContractEventArgs>(
+        eventName: ExchangeEvents, subscriptionOpts: SubscriptionOpts, indexFilterValues: IndexedFilterValues,
+    ): Promise<Array<LogWithDecodedArgs<ArgsType>>> {
         assert.doesBelongToStringEnum('eventName', eventName, ExchangeEvents);
         assert.doesConformToSchema('subscriptionOpts', subscriptionOpts, schemas.subscriptionOptsSchema);
         assert.doesConformToSchema('indexFilterValues', indexFilterValues, schemas.indexFilterValuesSchema);
         const exchangeContractAddress = await this.getContractAddressAsync();
-        const logs = await this._getLogsAsync(
+        const logs = await this._getLogsAsync<ArgsType>(
             exchangeContractAddress, eventName, subscriptionOpts, indexFilterValues, artifacts.ExchangeArtifact.abi,
         );
         return logs;
@@ -799,12 +804,14 @@ export class ExchangeWrapper extends ContractWrapper {
     }
     /**
      * Checks if logs contain LogError, which is emmited by Exchange contract on transaction failure.
-     * @param   logsWithDecodedArgs   Transaction logs as returned by `zeroEx.awaitTransactionMinedAsync`
+     * @param   logs   Transaction logs as returned by `zeroEx.awaitTransactionMinedAsync`
      */
-    public throwLogErrorsAsErrors(logsWithDecodedArgs: LogWithDecodedArgs[]): void {
-        const errLog = _.find(logsWithDecodedArgs, {event: ExchangeEvents.LogError});
+    public throwLogErrorsAsErrors(logs: Array<LogWithDecodedArgs<DecodedLogArgs>|Web3.LogEntry>): void {
+        const errLog = _.find(logs, {
+            event: ExchangeEvents.LogError,
+        }) as LogWithDecodedArgs<LogErrorContractEventArgs>|undefined;
         if (!_.isUndefined(errLog)) {
-            const logArgs: LogErrorContractEventArgs = errLog.args as any;
+            const logArgs = errLog.args;
             const errCode = logArgs.errorId.toNumber();
             const errMessage = this._exchangeContractErrCodesToMsg[errCode];
             throw new Error(errMessage);
diff --git a/src/contract_wrappers/token_wrapper.ts b/src/contract_wrappers/token_wrapper.ts
index abd090f7e..8dc4e61c5 100644
--- a/src/contract_wrappers/token_wrapper.ts
+++ b/src/contract_wrappers/token_wrapper.ts
@@ -16,6 +16,7 @@ import {
     MethodOpts,
     LogWithDecodedArgs,
     EventCallback,
+    TokenContractEventArgs,
 } from '../types';
 
 const ALLOWANCE_TO_ZERO_GAS_AMOUNT = 47155;
@@ -251,13 +252,14 @@ export class TokenWrapper extends ContractWrapper {
      * @param   callback            Callback that gets called when a log is added/removed
      * @return Subscription token used later to unsubscribe
      */
-    public subscribe(tokenAddress: string, eventName: TokenEvents, indexFilterValues: IndexedFilterValues,
-                     callback: EventCallback): string {
+    public subscribe<ArgsType extends TokenContractEventArgs>(
+        tokenAddress: string, eventName: TokenEvents, indexFilterValues: IndexedFilterValues,
+        callback: EventCallback<ArgsType>): string {
         assert.isETHAddressHex('tokenAddress', tokenAddress);
         assert.doesBelongToStringEnum('eventName', eventName, TokenEvents);
         assert.doesConformToSchema('indexFilterValues', indexFilterValues, schemas.indexFilterValuesSchema);
         assert.isFunction('callback', callback);
-        const subscriptionToken = this._subscribe(
+        const subscriptionToken = this._subscribe<ArgsType>(
             tokenAddress, eventName, indexFilterValues, artifacts.TokenArtifact.abi, callback,
         );
         this._activeSubscriptions.push(subscriptionToken);
@@ -280,13 +282,14 @@ export class TokenWrapper extends ContractWrapper {
      *                              the value is the value you are interested in. E.g `{_from: aUserAddressHex}`
      * @return  Array of logs that match the parameters
      */
-    public async getLogsAsync(tokenAddress: string, eventName: TokenEvents, subscriptionOpts: SubscriptionOpts,
-                              indexFilterValues: IndexedFilterValues): Promise<LogWithDecodedArgs[]> {
+    public async getLogsAsync<ArgsType extends TokenContractEventArgs>(
+        tokenAddress: string, eventName: TokenEvents, subscriptionOpts: SubscriptionOpts,
+        indexFilterValues: IndexedFilterValues): Promise<Array<LogWithDecodedArgs<ArgsType>>> {
         assert.isETHAddressHex('tokenAddress', tokenAddress);
         assert.doesBelongToStringEnum('eventName', eventName, TokenEvents);
         assert.doesConformToSchema('subscriptionOpts', subscriptionOpts, schemas.subscriptionOptsSchema);
         assert.doesConformToSchema('indexFilterValues', indexFilterValues, schemas.indexFilterValuesSchema);
-        const logs = await this._getLogsAsync(
+        const logs = await this._getLogsAsync<ArgsType>(
             tokenAddress, eventName, subscriptionOpts, indexFilterValues, artifacts.TokenArtifact.abi,
         );
         return logs;
diff --git a/src/index.ts b/src/index.ts
index 048050c7a..f287a8c57 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -32,7 +32,6 @@ export {
     ZeroExConfig,
     TransactionReceiptWithDecodedLogs,
     LogWithDecodedArgs,
-    DecodedLogArgs,
     MethodOpts,
     OrderTransactionOpts,
     FilterObject,
diff --git a/src/types.ts b/src/types.ts
index 8c0bc1cf9..d933404b7 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -36,12 +36,12 @@ export type OrderAddresses = [string, string, string, string, string];
 export type OrderValues = [BigNumber.BigNumber, BigNumber.BigNumber, BigNumber.BigNumber,
                            BigNumber.BigNumber, BigNumber.BigNumber, BigNumber.BigNumber];
 
-export interface LogEvent extends LogWithDecodedArgs {
+export interface LogEvent<ArgsType> extends LogWithDecodedArgs<ArgsType> {
     removed: boolean;
 }
-export type EventCallbackAsync = (log: LogEvent) => Promise<void>;
-export type EventCallbackSync = (log: LogEvent) => void;
-export type EventCallback = EventCallbackSync|EventCallbackAsync;
+export type EventCallbackAsync<ArgsType> = (log: LogEvent<ArgsType>) => Promise<void>;
+export type EventCallbackSync<ArgsType> = (log: LogEvent<ArgsType>) => void;
+export type EventCallback<ArgsType> = EventCallbackSync<ArgsType>|EventCallbackAsync<ArgsType>;
 export interface ExchangeContract extends Web3.ContractInstance {
     isValidSignature: {
         callAsync: (signerAddressHex: string, dataHex: string, v: number, r: string, s: string,
@@ -419,15 +419,15 @@ export interface DecodedLogArgs {
     [argName: string]: ContractEventArg;
 }
 
-export interface DecodedArgs {
-    args: DecodedLogArgs;
+export interface DecodedArgs<ArgsType> {
+    args: ArgsType;
     event: string;
 }
 
-export interface LogWithDecodedArgs extends Web3.LogEntry, DecodedArgs {}
+export interface LogWithDecodedArgs<ArgsType> extends Web3.LogEntry, DecodedArgs<ArgsType> {}
 
 export interface TransactionReceiptWithDecodedLogs extends Web3.TransactionReceipt {
-    logs: Array<LogWithDecodedArgs|Web3.LogEntry>;
+    logs: Array<LogWithDecodedArgs<DecodedLogArgs>|Web3.LogEntry>;
 }
 
 export interface Artifact {
diff --git a/src/utils/abi_decoder.ts b/src/utils/abi_decoder.ts
index 52b114c12..a6c45bee7 100644
--- a/src/utils/abi_decoder.ts
+++ b/src/utils/abi_decoder.ts
@@ -1,7 +1,7 @@
 import * as Web3 from 'web3';
 import * as _ from 'lodash';
 import * as BigNumber from 'bignumber.js';
-import {AbiType, DecodedLogArgs, LogWithDecodedArgs, RawLog, SolidityTypes} from '../types';
+import {AbiType, DecodedLogArgs, LogWithDecodedArgs, RawLog, SolidityTypes, ContractEventArgs} from '../types';
 import * as SolidityCoder from 'web3/lib/solidity/coder';
 
 export class AbiDecoder {
@@ -11,7 +11,8 @@ export class AbiDecoder {
         _.map(abiArrays, this.addABI.bind(this));
     }
     // This method can only decode logs from the 0x smart contracts
-    public tryToDecodeLogOrNoop(log: Web3.LogEntry): LogWithDecodedArgs|RawLog {
+    public tryToDecodeLogOrNoop<ArgsType extends ContractEventArgs>(
+        log: Web3.LogEntry): LogWithDecodedArgs<ArgsType>|RawLog {
         const methodId = log.topics[0];
         const event = this.methodIds[methodId];
         if (_.isUndefined(event)) {
diff --git a/test/0x.js_test.ts b/test/0x.js_test.ts
index cc6b91e99..dd5dd19b1 100644
--- a/test/0x.js_test.ts
+++ b/test/0x.js_test.ts
@@ -4,7 +4,7 @@ import {chaiSetup} from './utils/chai_setup';
 import 'mocha';
 import * as BigNumber from 'bignumber.js';
 import * as Sinon from 'sinon';
-import {ZeroEx, Order, ZeroExError, LogWithDecodedArgs} from '../src';
+import {ZeroEx, Order, ZeroExError, LogWithDecodedArgs, ApprovalContractEventArgs, TokenEvents} from '../src';
 import {constants} from './utils/constants';
 import {TokenUtils} from './utils/token_utils';
 import {web3Factory} from './utils/web3_factory';
@@ -223,8 +223,8 @@ describe('ZeroEx library', () => {
             const proxyAddress = await zeroEx.proxy.getContractAddressAsync();
             const txHash = await zeroEx.token.setUnlimitedProxyAllowanceAsync(zrxTokenAddress, coinbase);
             const txReceiptWithDecodedLogs = await zeroEx.awaitTransactionMinedAsync(txHash);
-            const log = txReceiptWithDecodedLogs.logs[0] as LogWithDecodedArgs;
-            expect(log.event).to.be.equal('Approval');
+            const log = txReceiptWithDecodedLogs.logs[0] as LogWithDecodedArgs<ApprovalContractEventArgs>;
+            expect(log.event).to.be.equal(TokenEvents.Approval);
             expect(log.args._owner).to.be.equal(coinbase);
             expect(log.args._spender).to.be.equal(proxyAddress);
             expect(log.args._value).to.be.bignumber.equal(zeroEx.token.UNLIMITED_ALLOWANCE_IN_BASE_UNITS);
diff --git a/test/exchange_wrapper_test.ts b/test/exchange_wrapper_test.ts
index afc33f1f4..1bedfc4da 100644
--- a/test/exchange_wrapper_test.ts
+++ b/test/exchange_wrapper_test.ts
@@ -18,6 +18,7 @@ import {
     OrderCancellationRequest,
     OrderFillRequest,
     LogFillContractEventArgs,
+    LogCancelContractEventArgs,
     OrderFillOrKillRequest,
     LogEvent,
 } from '../src';
@@ -651,7 +652,7 @@ describe('ExchangeWrapper', () => {
         // Source: https://github.com/mochajs/mocha/issues/2407
         it('Should receive the LogFill event when an order is filled', (done: DoneCallback) => {
             (async () => {
-                const callback = (logEvent: LogEvent) => {
+                const callback = (logEvent: LogEvent<LogFillContractEventArgs>) => {
                     expect(logEvent.event).to.be.equal(ExchangeEvents.LogFill);
                     done();
                 };
@@ -665,7 +666,7 @@ describe('ExchangeWrapper', () => {
         });
         it('Should receive the LogCancel event when an order is cancelled', (done: DoneCallback) => {
             (async () => {
-                const callback = (logEvent: LogEvent) => {
+                const callback = (logEvent: LogEvent<LogCancelContractEventArgs>) => {
                     expect(logEvent.event).to.be.equal(ExchangeEvents.LogCancel);
                     done();
                 };
@@ -677,7 +678,7 @@ describe('ExchangeWrapper', () => {
         });
         it('Outstanding subscriptions are cancelled when zeroEx.setProviderAsync called', (done: DoneCallback) => {
             (async () => {
-                const callbackNeverToBeCalled = (logEvent: LogEvent) => {
+                const callbackNeverToBeCalled = (logEvent: LogEvent<LogFillContractEventArgs>) => {
                     done(new Error('Expected this subscription to have been cancelled'));
                 };
                 await zeroEx.exchange.subscribeAsync(
@@ -687,7 +688,7 @@ describe('ExchangeWrapper', () => {
                 const newProvider = web3Factory.getRpcProvider();
                 await zeroEx.setProviderAsync(newProvider);
 
-                const callback = (logEvent: LogEvent) => {
+                const callback = (logEvent: LogEvent<LogFillContractEventArgs>) => {
                     expect(logEvent.event).to.be.equal(ExchangeEvents.LogFill);
                     done();
                 };
@@ -701,7 +702,7 @@ describe('ExchangeWrapper', () => {
         });
         it('Should cancel subscription when unsubscribe called', (done: DoneCallback) => {
             (async () => {
-                const callbackNeverToBeCalled = (logEvent: LogEvent) => {
+                const callbackNeverToBeCalled = (logEvent: LogEvent<LogFillContractEventArgs>) => {
                     done(new Error('Expected this subscription to have been cancelled'));
                 };
                 const subscriptionToken = await zeroEx.exchange.subscribeAsync(
@@ -811,11 +812,12 @@ describe('ExchangeWrapper', () => {
             const indexFilterValues = {
                 maker: differentMakerAddress,
             };
-            const logs = await zeroEx.exchange.getLogsAsync(
+            const logs = await zeroEx.exchange.getLogsAsync<LogFillContractEventArgs>(
                 eventName, subscriptionOpts, indexFilterValues,
             );
             expect(logs).to.have.length(1);
-            expect(logs[0].args.maker).to.be.equal(differentMakerAddress);
+            const args = logs[0].args;
+            expect(args.maker).to.be.equal(differentMakerAddress);
         });
     });
 });
diff --git a/test/token_wrapper_test.ts b/test/token_wrapper_test.ts
index 50f2db2ac..f1f6543b7 100644
--- a/test/token_wrapper_test.ts
+++ b/test/token_wrapper_test.ts
@@ -14,6 +14,7 @@ import {
     ContractEvent,
     TransferContractEventArgs,
     ApprovalContractEventArgs,
+    TokenContractEventArgs,
     LogWithDecodedArgs,
     LogEvent,
 } from '../src';
@@ -357,9 +358,9 @@ describe('TokenWrapper', () => {
         // Source: https://github.com/mochajs/mocha/issues/2407
         it('Should receive the Transfer event when tokens are transfered', (done: DoneCallback) => {
             (async () => {
-                const callback = (logEvent: LogEvent) => {
+                const callback = (logEvent: LogEvent<TransferContractEventArgs>) => {
                     expect(logEvent).to.not.be.undefined();
-                    const args = logEvent.args as any as TransferContractEventArgs;
+                    const args = logEvent.args;
                     expect(args._from).to.be.equal(coinbase);
                     expect(args._to).to.be.equal(addressWithoutFunds);
                     expect(args._value).to.be.bignumber.equal(transferAmount);
@@ -372,9 +373,9 @@ describe('TokenWrapper', () => {
         });
         it('Should receive the Approval event when allowance is being set', (done: DoneCallback) => {
             (async () => {
-                const callback = (logEvent: LogEvent) => {
+                const callback = (logEvent: LogEvent<ApprovalContractEventArgs>) => {
                     expect(logEvent).to.not.be.undefined();
-                    const args = logEvent.args as any as ApprovalContractEventArgs;
+                    const args = logEvent.args;
                     expect(args._owner).to.be.equal(coinbase);
                     expect(args._spender).to.be.equal(addressWithoutFunds);
                     expect(args._value).to.be.bignumber.equal(allowanceAmount);
@@ -387,13 +388,13 @@ describe('TokenWrapper', () => {
         });
         it('Outstanding subscriptions are cancelled when zeroEx.setProviderAsync called', (done: DoneCallback) => {
             (async () => {
-                const callbackNeverToBeCalled = (logEvent: LogEvent) => {
+                const callbackNeverToBeCalled = (logEvent: LogEvent<TransferContractEventArgs>) => {
                     done(new Error('Expected this subscription to have been cancelled'));
                 };
                 zeroEx.token.subscribe(
                     tokenAddress, TokenEvents.Transfer, indexFilterValues, callbackNeverToBeCalled,
                 );
-                const callbackToBeCalled = (logEvent: LogEvent) => {
+                const callbackToBeCalled = (logEvent: LogEvent<TransferContractEventArgs>) => {
                     done();
                 };
                 const newProvider = web3Factory.getRpcProvider();
@@ -406,7 +407,7 @@ describe('TokenWrapper', () => {
         });
         it('Should cancel subscription when unsubscribe called', (done: DoneCallback) => {
             (async () => {
-                const callbackNeverToBeCalled = (logEvent: LogEvent) => {
+                const callbackNeverToBeCalled = (logEvent: LogEvent<TokenContractEventArgs>) => {
                     done(new Error('Expected this subscription to have been cancelled'));
                 };
                 const subscriptionToken = zeroEx.token.subscribe(
@@ -435,14 +436,15 @@ describe('TokenWrapper', () => {
             await zeroEx.awaitTransactionMinedAsync(txHash);
             const eventName = TokenEvents.Approval;
             const indexFilterValues = {};
-            const logs = await zeroEx.token.getLogsAsync(
+            const logs = await zeroEx.token.getLogsAsync<ApprovalContractEventArgs>(
                 tokenAddress, eventName, subscriptionOpts, indexFilterValues,
             );
             expect(logs).to.have.length(1);
+            const args = logs[0].args;
             expect(logs[0].event).to.be.equal(eventName);
-            expect(logs[0].args._owner).to.be.equal(coinbase);
-            expect(logs[0].args._spender).to.be.equal(tokenTransferProxyAddress);
-            expect(logs[0].args._value).to.be.bignumber.equal(zeroEx.token.UNLIMITED_ALLOWANCE_IN_BASE_UNITS);
+            expect(args._owner).to.be.equal(coinbase);
+            expect(args._spender).to.be.equal(tokenTransferProxyAddress);
+            expect(args._value).to.be.bignumber.equal(zeroEx.token.UNLIMITED_ALLOWANCE_IN_BASE_UNITS);
         });
         it('should only get the logs with the correct event name', async () => {
             txHash = await zeroEx.token.setUnlimitedProxyAllowanceAsync(tokenAddress, coinbase);
@@ -463,11 +465,12 @@ describe('TokenWrapper', () => {
             const indexFilterValues = {
                 _owner: coinbase,
             };
-            const logs = await zeroEx.token.getLogsAsync(
+            const logs = await zeroEx.token.getLogsAsync<ApprovalContractEventArgs>(
                 tokenAddress, eventName, subscriptionOpts, indexFilterValues,
             );
             expect(logs).to.have.length(1);
-            expect(logs[0].args._owner).to.be.equal(coinbase);
+            const args = logs[0].args;
+            expect(args._owner).to.be.equal(coinbase);
         });
     });
 });