feat(@angular-devkit/build-angular): support web workers in karma builder

Followup to #13700, the karma builder did not get the same support but it should.

Author: filipesilva

packages/angular_devkit/build_angular/src/angular-cli-files/models/webpack-configs/worker.ts

@@ -15,7 +15,12 @@ const WorkerPlugin = require('worker-plugin');
 
 export function getWorkerConfig(wco: WebpackConfigOptions): Configuration {
   const { buildOptions } = wco;
+
   if (!buildOptions.webWorkerTsConfig) {
+    return {};
+  }
+
+  if (typeof buildOptions.webWorkerTsConfig != 'string') {
     throw new Error('The `webWorkerTsConfig` must be a string.');
   }
 

packages/angular_devkit/build_angular/src/browser/index.ts

@@ -155,6 +155,7 @@ export function buildWebpackConfig(
       getBrowserConfig(wco),
       getStylesConfig(wco),
       getStatsConfig(wco),
+      getWorkerConfig(wco),
     ];
 
     if (wco.buildOptions.main || wco.buildOptions.polyfills) {
@@ -179,10 +180,6 @@ export function buildWebpackConfig(
       });
     }
 
-    if (wco.buildOptions.webWorkerTsConfig) {
-      webpackConfigs.push(getWorkerConfig(wco));
-    }
-
     const webpackConfig = webpackMerge(webpackConfigs);
 
     if (options.profile || process.env['NG_BUILD_PROFILING']) {

packages/angular_devkit/build_angular/src/karma/index.ts

@@ -15,6 +15,7 @@ import {
   getNonAotConfig,
   getStylesConfig,
   getTestConfig,
+  getWorkerConfig,
 } from '../angular-cli-files/models/webpack-configs';
 import { Schema as BrowserBuilderOptions } from '../browser/schema';
 import { generateBrowserWebpackConfigFromContext } from '../utils/webpack-browser-config';
@@ -44,6 +45,7 @@ async function initialize(
       getStylesConfig(wco),
       getNonAotConfig(wco),
       getTestConfig(wco),
+      getWorkerConfig(wco),
     ],
   );
 

packages/angular_devkit/build_angular/src/karma/schema.json

@@ -185,6 +185,10 @@
       "items": {
         "type": "string"
       }
+    },
+    "webWorkerTsConfig": {
+      "type": "string",
+      "description": "TypeScript configuration for Web Worker modules."
     }
   },
   "additionalProperties": false,