fix: remove ES6 features since this also now runs on the browser

test/debug_spec.js

@@ -1,32 +1,33 @@
 /* global describe, it */
+'use strict'
 
-if (typeof module !== 'undefined' && module.exports) {
-  const chai = require('chai');
-  const expect = chai.expect;
+if (typeof module !== 'undefined') {
+  var chai = require('chai');
+  var expect = chai.expect;
 
-  const debug = require('../src/index');
-  const sinon = require('sinon');
+  var debug = require('../src/index');
+  var sinon = require('sinon');
   var sinonChai = require("sinon-chai");
   chai.use(sinonChai);
 }
 
-const dummyConsole = {
+var dummyConsole = {
   log: function() {
     //dummy function
   }
 };
 
-debug.log = dummyConsole;
-
 
 describe('debug', function () {
-  const log = debug('test');
+  var log = debug('test');
+
   log.log = sinon.stub();
     it('passes a basic sanity check', function () {
       expect(log('hello world')).to.not.throw;
     });
 
     it('Should output to the log function', function () {
+      debug.log = dummyConsole.log;
       sinon.spy(dummyConsole, 'log');
       log('Hello world');
       //expect(dummyConsole.log).to.have.been.called;