Add BigNumber support to expectEvent/inLogs (#1026) (#1338)

* Add BigNumber support to expectEvent/inLogs (#1026)

* switched direct logs array check to expectEvent method in AllowanceCrowdsale.test.js

* Refactor expectEvent.inLogs function to use simple value number check

* Introduced should.be.bignumber method to compare BigNumber values

* Destructure transaction object to extract logs field

test/crowdsale/AllowanceCrowdsale.test.js

+const expectEvent = require('../helpers/expectEvent');
 const { ether } = require('../helpers/ether');
 const { assertRevert } = require('../helpers/assertRevert');
 const { ethGetBalance } = require('../helpers/web3');
 
 const BigNumber = web3.BigNumber;
 
-const should = require('chai')
+require('chai')
   .use(require('chai-bignumber')(BigNumber))
   .should();
 
@@ -41,12 +42,14 @@ contract('AllowanceCrowdsale', function ([_, investor, wallet, purchaser, tokenW
   describe('high-level purchase', function () {
     it('should log purchase', async function () {
       const { logs } = await this.crowdsale.sendTransaction({ value: value, from: investor });
-      const event = logs.find(e => e.event === 'TokensPurchased');
-      should.exist(event);
-      event.args.purchaser.should.equal(investor);
-      event.args.beneficiary.should.equal(investor);
-      event.args.value.should.be.bignumber.equal(value);
-      event.args.amount.should.be.bignumber.equal(expectedTokenAmount);
+      expectEvent.inLogs(
+        logs,
+        'TokensPurchased',
+        {
+          purchaser: investor,
+          beneficiary: investor,
+          value: value,
+          amount: expectedTokenAmount });
     });
 
     it('should assign tokens to sender', async function () {

test/helpers/expectEvent.js

-const should = require('chai').should();
+const BigNumber = web3.BigNumber;
+const should = require('chai')
+  .use(require('chai-bignumber')(BigNumber))
+  .should();
 
 function inLogs (logs, eventName, eventArgs = {}) {
   const event = logs.find(function (e) {
     if (e.event === eventName) {
-      let matches = true;
-
       for (const [k, v] of Object.entries(eventArgs)) {
-        if (e.args[k] !== v) {
-          matches = false;
-        }
+        contains(e.args, k, v);
       }
-
-      if (matches) {
       return true;
     }
-    }
   });
-
   should.exist(event);
-
   return event;
 }
 
@@ -27,6 +21,20 @@ async function inTransaction (tx, eventName, eventArgs = {}) {
   return inLogs(logs, eventName, eventArgs);
 }
 
+function contains (args, key, value) {
+  if (isBigNumber(args[key])) {
+    args[key].should.be.bignumber.equal(value);
+  } else {
+    args[key].should.be.equal(value);
+  }
+}
+
+function isBigNumber (object) {
+  return object.isBigNumber ||
+    object instanceof BigNumber ||
+    (object.constructor && object.constructor.name === 'BigNumber');
+}
+
 module.exports = {
   inLogs,
   inTransaction,