fix karma coverage report

config/karma.config.js

@@ -13,9 +13,17 @@ module.exports = function(config) {
       { pattern: 'spec/javascripts/fixtures/**/*@(.json|.html|.html.raw)', included: false },
     ],
     preprocessors: {
-      'spec/javascripts/**/*.js?(.es6)': ['webpack', 'sourcemap'],
+      'spec/javascripts/**/*.js?(.es6)': ['webpack', 'sourcemap', 'coverage'],
     },
+    reporters: ['progress', 'coverage'],
     webpack: webpackConfig,
     webpackMiddleware: { stats: 'errors-only' },
+    coverageReporter: {
+      dir: './coverage-javascript',
+      reporters: [
+        { type: 'html', subdir: 'default' },
+        { type: 'text-summary' }
+      ],
+    }
   });
 };

package.json

@@ -43,6 +43,7 @@
     "jasmine-core": "^2.5.2",
     "jasmine-jquery": "^2.1.1",
     "karma": "^1.3.0",
+    "karma-coverage": "^1.1.1",
     "karma-jasmine": "^1.1.0",
     "karma-phantomjs-launcher": "^1.0.2",
     "karma-sourcemap-loader": "^0.3.7",