test(@angular/build): add E2E test for Vitest browser mode with coverage

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

@@ -232,16 +232,12 @@ export async function createVitestConfigPlugin(
         delete config.plugins;
       }
 
-      // Add browser source map support if coverage is enabled
+      // Validate browser coverage support if coverage is enabled
       if (
         (browser || testConfig?.browser?.enabled) &&
         (options.coverage.enabled || testConfig?.coverage?.enabled)
       ) {
-        // Validate that enabled browsers support the selected coverage provider
         validateBrowserCoverage(browser, testConfig?.browser, determinedProvider);
-
-        projectPlugins.unshift(createSourcemapSupportPlugin());
-        setupFiles.unshift('virtual:source-map-support');
       }
 
       const projectResolver = createRequire(projectSourceRoot + '/').resolve;
@@ -408,7 +404,7 @@ export function createVitestPlugins(pluginOptions: PluginOptions): VitestPlugins
 
           const map = sourceMapText ? JSON.parse(sourceMapText) : undefined;
           if (map) {
-            adjustSourcemapSources(map, !vitestConfig?.coverage?.enabled, workspaceRoot, id);
+            adjustSourcemapSources(map, true, workspaceRoot, id);
           }
 
           return {
@@ -475,36 +471,6 @@ function adjustSourcemapSources(
   }
 }
 
-function createSourcemapSupportPlugin(): VitestPlugins[0] {
-  return {
-    name: 'angular:source-map-support',
-    enforce: 'pre',
-    resolveId(source) {
-      if (source.includes('virtual:source-map-support')) {
-        return '\0source-map-support';
-      }
-    },
-    async load(id) {
-      if (id !== '\0source-map-support') {
-        return;
-      }
-
-      const packageResolve = createRequire(__filename).resolve;
-      const supportPath = packageResolve('source-map-support/browser-source-map-support.js');
-
-      const content = await readFile(supportPath, 'utf-8');
-
-      // The `source-map-support` library currently relies on `this` being defined in the global scope.
-      // However, when running in an ESM environment, `this` is undefined.
-      // To workaround this, we patch the library to use `globalThis` instead of `this`.
-      return (
-        content.replaceAll(/this\.(define|sourceMapSupport|base64js)/g, 'globalThis.$1') +
-        '\n;globalThis.sourceMapSupport.install();'
-      );
-    },
-  };
-}
-
 interface CustomBrowserConfigOptions {
   enabled?: boolean;
   instances?: { browser: string }[];

tests/e2e/tests/vitest/browser-coverage-sourcemaps.ts

@@ -0,0 +1,43 @@
+import assert from 'node:assert/strict';
+import { applyVitestBuilder } from '../../utils/vitest';
+import { ng } from '../../utils/process';
+import { installPackage } from '../../utils/packages';
+import { expectFileToExist, readFile } from '../../utils/fs';
+
+export default async function (): Promise<void> {
+  await applyVitestBuilder();
+  await installPackage('playwright@1');
+  await installPackage('@vitest/browser-playwright@4');
+  await installPackage('@vitest/coverage-v8@4');
+
+  // Run tests with coverage in browser mode.
+  // We use the default passing tests generated for the project.
+  const { stdout } = await ng(
+    'test',
+    '--no-watch',
+    '--browsers',
+    'chromiumHeadless',
+    '--coverage',
+    '--coverage-reporters=json-summary',
+  );
+
+  // Verify that tests passed
+  assert.match(stdout, /pass/, 'Expected tests to run successfully.');
+
+  // Verify that coverage files are generated
+  const summaryPath = 'coverage/test-project/coverage-summary.json';
+  await expectFileToExist(summaryPath);
+
+  const summary = JSON.parse(await readFile(summaryPath));
+
+  // Find the key for app.ts (it might be an absolute path)
+  const appFileKey = Object.keys(summary).find((key) => key.endsWith('app.ts'));
+  assert.ok(appFileKey, 'Expected coverage summary to contain app.ts.');
+
+  const appCoverage = summary[appFileKey];
+  assert.ok(appCoverage.lines.pct > 0, 'Expected lines percentage to be greater than 0.');
+
+  // Also verify that spec files are NOT present in the summary
+  const specFileKey = Object.keys(summary).find((key) => key.endsWith('.spec.ts'));
+  assert.ok(!specFileKey, 'Expected coverage report to not contain .spec.ts files.');
+}