fix(@angular/build): inject zone.js/testing before karma builder execution

`unit-test` builder doesn't inject `zone.js/testing` for `Karma` runner but only for `Vitest`.

Closes: #30595

Author: lacolaco

packages/angular/build/src/builders/unit-test/builder.ts

@@ -24,7 +24,7 @@ import { OutputHashing } from '../application/schema';
 import { writeTestFiles } from '../karma/application_builder';
 import { findTests, getTestEntrypoints } from '../karma/find-tests';
 import { useKarmaBuilder } from './karma-bridge';
-import { NormalizedUnitTestOptions, normalizeOptions } from './options';
+import { NormalizedUnitTestOptions, injectTestingPolyfills, normalizeOptions } from './options';
 import type { Schema as UnitTestOptions } from './schema';
 
 export type { UnitTestOptions };
@@ -111,9 +111,7 @@ export async function* execute(
     await context.getBuilderNameForTarget(normalizedOptions.buildTarget),
   )) as unknown as ApplicationBuilderInternalOptions;
 
-  if (buildTargetOptions.polyfills?.includes('zone.js')) {
-    buildTargetOptions.polyfills.push('zone.js/testing');
-  }
+  buildTargetOptions.polyfills = injectTestingPolyfills(buildTargetOptions.polyfills);
 
   const outputPath = path.join(context.workspaceRoot, generateOutputPath());
   const buildOptions: ApplicationBuilderInternalOptions = {

packages/angular/build/src/builders/unit-test/karma-bridge.ts

@@ -9,7 +9,7 @@
 import type { BuilderContext, BuilderOutput } from '@angular-devkit/architect';
 import type { ApplicationBuilderInternalOptions } from '../application/options';
 import type { KarmaBuilderOptions } from '../karma';
-import type { NormalizedUnitTestOptions } from './options';
+import { type NormalizedUnitTestOptions, injectTestingPolyfills } from './options';
 
 export async function useKarmaBuilder(
   context: BuilderContext,
@@ -26,6 +26,8 @@ export async function useKarmaBuilder(
     await context.getBuilderNameForTarget(unitTestOptions.buildTarget),
   )) as unknown as ApplicationBuilderInternalOptions;
 
+  buildTargetOptions.polyfills = injectTestingPolyfills(buildTargetOptions.polyfills);
+
   const options: KarmaBuilderOptions = {
     tsConfig: unitTestOptions.tsConfig,
     polyfills: buildTargetOptions.polyfills,

packages/angular/build/src/builders/unit-test/options.ts

@@ -64,3 +64,7 @@ export async function normalizeOptions(
     providersFile: options.providersFile && path.join(workspaceRoot, options.providersFile),
   };
 }
+
+export function injectTestingPolyfills(polyfills: string[] = []): string[] {
+  return polyfills.includes('zone.js') ? [...polyfills, 'zone.js/testing'] : polyfills;
+}