Test setup helper added (#1482)

* 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 #1404

* approve failing test

* suggested changes done

* ISafeERC20 removed

* conflict fixes

* fixes #1205

* minor change

* suggested changes

* reviewed changes

* final update

test/helpers/shouldFail.js

@@ -1,5 +1,4 @@
-const should = require('chai')
-  .should();
+const { should } = require('./setup');
 
 async function shouldFailWithMessage (promise, message) {
   try {