test(@angular/build): add e2e for larger project with Vitest coverage

Adds an end-to-end test to verify Vitest coverage collection and threshold
enforcement for a larger number of generated components, services, and pipes.
This test ensures that all generated source files are correctly included in
the coverage report in both JSDOM and browser environments.

Author: clydin

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

@@ -0,0 +1,100 @@
+import { ng } from '../../utils/process';
+import { applyVitestBuilder } from '../../utils/vitest';
+import assert from 'node:assert';
+import { installPackage } from '../../utils/packages';
+import { exec } from '../../utils/process';
+import { updateJsonFile } from '../../utils/project';
+import { readFile } from '../../utils/fs';
+
+export default async function () {
+  await applyVitestBuilder();
+  await installPackage('@vitest/coverage-v8@4');
+
+  // Add coverage and threshold configuration to ensure coverage is calculated.
+  // Use the 'json' reporter to get a machine-readable output for assertions.
+  await updateJsonFile('angular.json', (json) => {
+    const project = Object.values(json['projects'])[0] as any;
+    const test = project['architect']['test'];
+    test.options = {
+      coverageReporters: ['json', 'text'],
+      coverageThresholds: {
+        // The generated component/service/pipe files are basic
+        // A threshold of 75 should be safe.
+        statements: 75,
+      },
+    };
+  });
+
+  const artifactCount = 100;
+  const initialTestCount = 1;
+  const generatedFiles: string[] = [];
+
+  // Generate a mix of components, services, and pipes
+  for (let i = 0; i < artifactCount; i++) {
+    const type = i % 3;
+    const name = `test-artifact${i}`;
+    let generateType;
+    let fileSuffix;
+
+    switch (type) {
+      case 0:
+        generateType = 'component';
+        fileSuffix = '.ts';
+        break;
+      case 1:
+        generateType = 'service';
+        fileSuffix = '.ts';
+        break;
+      default:
+        generateType = 'pipe';
+        fileSuffix = '-pipe.ts';
+        break;
+    }
+
+    await ng('generate', generateType, name, '--skip-tests=false');
+    generatedFiles.push(`${name}${fileSuffix}`);
+  }
+
+  const totalTests = initialTestCount + artifactCount;
+  const expectedMessage = new RegExp(`${totalTests} passed`);
+  const coverageJsonPath = 'coverage/test-project/coverage-final.json';
+
+  // Run tests in default (JSDOM) mode with coverage
+  const { stdout: jsdomStdout } = await ng('test', '--no-watch', '--coverage');
+  assert.match(jsdomStdout, expectedMessage, `Expected ${totalTests} tests to pass in JSDOM mode.`);
+
+  // Assert that every generated file is in the coverage report by reading the JSON output.
+  const jsdomSummary = JSON.parse(await readFile(coverageJsonPath));
+  const jsdomSummaryKeys = Object.keys(jsdomSummary);
+  for (const file of generatedFiles) {
+    const found = jsdomSummaryKeys.some((key) => key.endsWith(file));
+    assert.ok(found, `Expected ${file} to be in the JSDOM coverage report.`);
+  }
+
+  // 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 with coverage
+  const { stdout: browserStdout } = await ng(
+    'test',
+    '--no-watch',
+    '--coverage',
+    '--browsers',
+    'ChromiumHeadless',
+  );
+  assert.match(
+    browserStdout,
+    expectedMessage,
+    `Expected ${totalTests} tests to pass in browser mode.`,
+  );
+
+  // Assert that every generated file is in the coverage report for browser mode.
+  const browserSummary = JSON.parse(await readFile(coverageJsonPath));
+  const browserSummaryKeys = Object.keys(browserSummary);
+  for (const file of generatedFiles) {
+    const found = browserSummaryKeys.some((key) => key.endsWith(file));
+    assert.ok(found, `Expected ${file} to be in the browser coverage report.`);
+  }
+}