added a test helper with common constants (#1400)

* signing prefix added

* Minor improvement

* Tests changed

* Successfully tested

* Minor improvements

* Minor improvements

* Revert "Dangling commas are now required. (#1359)"

This reverts commit a6889776f4.

* updates

* fixes #1206

test/examples/SimpleToken.test.js

@@ -1,4 +1,5 @@
 const { decodeLogs } = require('../helpers/decodeLogs');
+const { ZERO_ADDRESS } = require('../helpers/constants');
 const SimpleToken = artifacts.require('SimpleToken');
 
 const BigNumber = web3.BigNumber;
@@ -8,8 +9,6 @@ require('chai')
   .should();
 
 contract('SimpleToken', function ([_, creator]) {
-  const ZERO_ADDRESS = '0x0000000000000000000000000000000000000000';
-
   beforeEach(async function () {
     this.token = await SimpleToken.new({ from: creator });
   });