don't 404 missing scripts

Author: filipesilva

packages/@angular/cli/plugins/karma.ts

@@ -131,9 +131,16 @@ const init: any = (config: any, emitter: any, customFileHandlers: any) => {
 
   // The webpack tier owns the watch behavior so we want to force it in the config
   webpackConfig.watch = true;
+  // Files need to be served from a custom path for Karma.
   webpackConfig.output.path = '/_karma_webpack_/';
   webpackConfig.output.publicPath = '/_karma_webpack_/';
 
+
+  // webpackConfig.entry = Object.assign({}, {
+  //   scripts: [],
+  //   styles: []
+  // }, webpackConfig.entry)
+
   let compiler: any;
   try {
     compiler = webpack(webpackConfig);
@@ -168,8 +175,22 @@ const init: any = (config: any, emitter: any, customFileHandlers: any) => {
     urlRegex: /^\/_karma_webpack_\/.*/,
     handler: function handler(req: any, res: any) {
       middleware(req, res, function () {
-        res.statusCode = 404;
-        res.end('Not found');
+        // Ensure script and style bundles are served.
+        // They are mentioned in the custom karma context page and we don't want them to 404.
+        const alwaysServe = [
+          '/_karma_webpack_/inline.bundle.js',
+          '/_karma_webpack_/polyfills.bundle.js',
+          '/_karma_webpack_/scripts.bundle.js',
+          '/_karma_webpack_/styles.bundle.js',
+          '/_karma_webpack_/vendor.bundle.js',
+        ];
+        if (alwaysServe.indexOf(req.url) != -1) {
+          res.statusCode = 200;
+          res.end();
+        } else {
+          res.statusCode = 404;
+          res.end('Not found');
+        }
       });
     }
   });