fix(@angular-devkit/build-angular): sourceMap option not working in tests

Fixes #13766

Author: Alan Agius

packages/angular_devkit/build_angular/src/angular-cli-files/models/webpack-configs/test.ts

@@ -60,8 +60,8 @@ export function getTestConfig(
     const { styles, scripts } = wco.buildOptions.sourceMap;
 
     extraPlugins.push(getSourceMapDevTool(
-      styles,
-      scripts,
+      scripts || false,
+      styles || false,
       false,
       true,
     ));

tests/legacy-cli/e2e/tests/test/test-sourcemap.ts

@@ -0,0 +1,29 @@
+import { writeFile } from '../../utils/fs';
+import { execAndWaitForOutputToMatch, killAllProcesses } from '../../utils/process';
+import { updateJsonFile } from '../../utils/project';
+
+export default async function () {
+  await updateJsonFile('angular.json', configJson => {
+    const appArchitect = configJson.projects['test-project'].architect;
+    appArchitect.test.options.sourceMap = {
+      scripts: true,
+    };
+  });
+
+  await writeFile('src/app/app.component.spec.ts', `
+      it('show fail', () => {
+        expect(undefined).toBeTruthy();
+      });
+    `);
+
+  // when sourcemaps are not working the stacktrace won't point to the spec.ts file.
+  try {
+    await execAndWaitForOutputToMatch(
+      'ng',
+      ['test', '--watch', 'false'],
+      /app\.component\.spec\.ts/,
+    );
+  } finally {
+    killAllProcesses();
+  }
+}