test: improve vitest e2e test stability and performance

- Use Chrome binary from `rules_browsers` for Playwright in Vitest browser tests for hermetic testing.
- Batch `ng generate` commands in e2e tests to improve performance.
- Remove now redundant chromium install commands from e2e tests.

Author: alan-agius4

packages/angular/build/src/builders/unit-test/runners/vitest/browser-provider.ts

@@ -76,7 +76,21 @@ export async function setupBrowserConfiguration(
       // Validate that the imported module has the expected structure
       const providerFactory = providerModule[providerName];
       if (typeof providerFactory === 'function') {
-        provider = providerFactory();
+        if (
+          providerName === 'playwright' &&
+          process.env['CHROME_BIN']?.includes('rules_browsers')
+        ) {
+          // Use the Chrome binary from the 'rules_browsers' toolchain (via CHROME_BIN)
+          // for Playwright when available to ensure hermetic testing, preventing reliance
+          // on locally installed or NPM-managed browser versions.
+          provider = providerFactory({
+            launchOptions: {
+              executablePath: process.env.CHROME_BIN,
+            },
+          });
+        } else {
+          provider = providerFactory();
+        }
       } else {
         errors ??= [];
         errors.push(

tests/legacy-cli/e2e/tests/vitest/larger-project.ts

@@ -12,26 +12,7 @@ export default async function () {
   // Each generated artifact will add one more test file.
   const initialTestCount = 1;
 
-  // Generate a mix of components, services, and pipes
-  for (let i = 0; i < artifactCount; i++) {
-    const type = i % 3;
-    const name = `test-artifact-${i}`;
-    let generateType;
-
-    switch (type) {
-      case 0:
-        generateType = 'component';
-        break;
-      case 1:
-        generateType = 'service';
-        break;
-      default:
-        generateType = 'pipe';
-        break;
-    }
-
-    await ng('generate', generateType, name, '--skip-tests=false');
-  }
+  await generateArtifactsInBatches(artifactCount);
 
   const totalTests = initialTestCount + artifactCount;
   const expectedMessage = new RegExp(`${totalTests} passed`);
@@ -43,7 +24,6 @@ export default async function () {
   // Setup for browser mode
   await installPackage('playwright@1');
   await installPackage('@vitest/browser-playwright@4');
-  await exec('npx', 'playwright', 'install', 'chromium', '--only-shell');
 
   // Run tests in browser mode
   const { stdout: browserStdout } = await ng(
@@ -58,3 +38,33 @@ export default async function () {
     `Expected ${totalTests} tests to pass in browser mode.`,
   );
 }
+
+async function generateArtifactsInBatches(artifactCount: number): Promise<void> {
+  const BATCH_SIZE = 5;
+  let commands: Promise<any>[] = [];
+
+  for (let i = 0; i < artifactCount; i++) {
+    const type = i % 3;
+    const name = `test-artifact-${i}`;
+    let generateType: string;
+
+    switch (type) {
+      case 0:
+        generateType = 'component';
+        break;
+      case 1:
+        generateType = 'service';
+        break;
+      default:
+        generateType = 'pipe';
+        break;
+    }
+
+    commands.push(ng('generate', generateType, name, '--skip-tests=false'));
+
+    if (commands.length === BATCH_SIZE || i === artifactCount - 1) {
+      await Promise.all(commands);
+      commands = [];
+    }
+  }
+}

tests/legacy-cli/e2e/tests/vitest/tslib-resolution.ts

@@ -1,14 +1,13 @@
 import { writeFile } from '../../utils/fs';
 import { installPackage } from '../../utils/packages';
-import { exec, ng } from '../../utils/process';
+import { ng } from '../../utils/process';
 import { applyVitestBuilder } from '../../utils/vitest';
 import assert from 'node:assert';
 
 export default async function () {
   await applyVitestBuilder();
   await installPackage('playwright@1');
   await installPackage('@vitest/browser-playwright@4');
-  await exec('npx', 'playwright', 'install', 'chromium', '--only-shell');
 
   // Add a custom decorator to trigger tslib usage
   await writeFile(