feat(@angular-devkit/build-angular): karma builder main option is now optional

The Karma builder `main` option is now optional. The default test bootstrapping is injected automatically in the bundle.

Author: alan-agius4

goldens/public-api/angular_devkit/build_angular/index.md

@@ -178,7 +178,7 @@ export interface KarmaBuilderOptions {
     include?: string[];
     inlineStyleLanguage?: InlineStyleLanguage_2;
     karmaConfig: string;
-    main: string;
+    main?: string;
     poll?: number;
     polyfills?: Polyfills_2;
     preserveSymlinks?: boolean;

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

@@ -111,6 +111,17 @@ export function execute(
         throw new Error('The builder requires a target.');
       }
 
+      if (!options.main) {
+        webpackConfig.entry ??= {};
+        if (typeof webpackConfig.entry === 'object' && !Array.isArray(webpackConfig.entry)) {
+          if (Array.isArray(webpackConfig.entry['main'])) {
+            webpackConfig.entry['main'].push(getBuiltInMainFile());
+          } else {
+            webpackConfig.entry['main'] = [getBuiltInMainFile()];
+          }
+        }
+      }
+
       const projectMetadata = await context.getProjectMetadata(projectName);
       const sourceRoot = (projectMetadata.sourceRoot ?? projectMetadata.root ?? '') as string;
 
@@ -169,3 +180,23 @@ export function execute(
 
 export { KarmaBuilderOptions };
 export default createBuilder<Record<string, string> & KarmaBuilderOptions>(execute);
+
+function getBuiltInMainFile(): string {
+  const content = Buffer.from(
+    `
+  import { getTestBed } from '@angular/core/testing';
+  import {
+    BrowserDynamicTestingModule,
+    platformBrowserDynamicTesting,
+   } from '@angular/platform-browser-dynamic/testing';
+
+  // Initialize the Angular testing environment.
+  getTestBed().initTestEnvironment(BrowserDynamicTestingModule, platformBrowserDynamicTesting(), {
+    errorOnUnknownElements: true,
+    errorOnUnknownProperties: true
+  });
+`,
+  ).toString('base64');
+
+  return `ng-virtual-main.js!=!data:text/javascript;base64,${content}`;
+}

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

@@ -255,7 +255,7 @@
     }
   },
   "additionalProperties": false,
-  "required": ["main", "tsConfig", "karmaConfig"],
+  "required": ["tsConfig", "karmaConfig"],
   "definitions": {
     "assetPattern": {
       "oneOf": [

packages/angular_devkit/build_angular/src/builders/karma/tests/setup.ts

@@ -20,7 +20,6 @@ export const KARMA_BUILDER_INFO = Object.freeze({
  * Also disables progress reporting to minimize logging output.
  */
 export const BASE_OPTIONS = Object.freeze<Schema>({
-  main: 'src/test.ts',
   polyfills: 'src/polyfills.ts',
   tsConfig: 'src/tsconfig.spec.json',
   karmaConfig: 'karma.conf.js',

packages/angular_devkit/build_angular/src/webpack/configs/common.ts

@@ -130,7 +130,7 @@ export async function getCommonConfig(wco: WebpackConfigOptions): Promise<Config
       if (Array.isArray(entryPoints['main'])) {
         entryPoints['main'].unshift(zoneTestingEntryPoint);
       } else {
-        entryPoints['main'] = [zoneTestingEntryPoint, entryPoints['main'] as string];
+        entryPoints['main'] = [zoneTestingEntryPoint];
       }
     }
   }

packages/angular_devkit/build_angular/test/hello-world-app/angular.json

@@ -117,7 +117,6 @@
         "test": {
           "builder": "@angular-devkit/build-angular:karma",
           "options": {
-            "main": "src/test.ts",
             "polyfills": "src/polyfills.ts",
             "tsConfig": "src/tsconfig.spec.json",
             "karmaConfig": "karma.conf.js",

packages/angular_devkit/build_angular/test/hello-world-app/src/test.ts

@@ -7,7 +7,6 @@
     ]
   },
   "files": [
-    "test.ts",
     "polyfills.ts"
   ],
   "include": [

packages/angular_devkit/build_angular/test/hello-world-app/src/tsconfig.spec.json

@@ -7,7 +7,6 @@
     "types": []
   },
   "exclude": [
-    "src/test.ts",
     "**/*.spec.ts"
   ]
 }