fix(karma): set defaults for karma.conf.js

The karma plugin is currently overwriting configuration set in karma.conf.js instead of merging existing values. This fix will set defaults but not overwrite existing configuration.

Author: JSMike

plugins/karma.js

@@ -7,10 +7,7 @@ const init = (config) => {
   if (!config.angularCliConfig) throw new Error('Missing \'angularCliConfig\' entry in Karma config');
   const angularCliConfig = require(path.join(config.basePath, config.angularCliConfig));
   const appConfig = angularCliConfig.apps[0];
-
-  // add webpack config
-  config.webpack = getWebpackTestConfig(config.basePath, appConfig);
-  config.webpackMiddleware = {
+  const webpackMiddlewareConfig =     {
     noInfo: true, // Hide webpack output because its noisy.
     stats: { // Also prevent chunk and module display output, cleaner look. Only emit errors.
       assets: false,
@@ -23,6 +20,10 @@ const init = (config) => {
     }
   };
 
+  // add webpack config
+  config.webpack = Object.assign(getWebpackTestConfig(config.basePath, appConfig), config.webpack);
+  config.webpackMiddleware = Object.assign(webpackMiddlewareConfig, config.webpackMiddleware);
+
   // replace the angular-cli preprocessor with webpack+sourcemap
   Object.keys(config.preprocessors)
     .filter((file) => config.preprocessors[file].indexOf('angular-cli') !== -1)
@@ -40,4 +41,4 @@ preprocessor.$inject = []
 module.exports = Object.assign({
   'framework:angular-cli': ['factory', init],
   'preprocessor:angular-cli': ['factory', preprocessor]
-}, require('karma-webpack'), require('karma-sourcemap-loader'));
+}, require('karma-webpack'), require('karma-sourcemap-loader'));