Better diffs for specs.

test/unit/karma.conf.js

@@ -55,7 +55,7 @@ module.exports = function (config) {
     // 2. add it to the `browsers` array below.
     browsers: ['PhantomJS'],
     frameworks: ['mocha', 'sinon-chai'],
-    reporters: ['spec'],
+    reporters: ['mocha'],
     files: ['./index.js'],
     preprocessors: {
       './index.js': ['webpack', 'sourcemap']
@@ -64,6 +64,9 @@ module.exports = function (config) {
     webpackMiddleware: {
       noInfo: true
     },
+    mochaReporter: {
+      showDiff: true
+    },
     coverageReporter: {
       dir: './coverage',
       reporters: [