fix(@angular/build): resolve junit karma reporter output to workspace root

To maintain behavior with the Webpack-based karma unit-testing available
via `@angular-devkit/build-angular`, the application build system based
karma testing will now resolve the output directory location of the junit
karma reporter to the same workspace root location.  This is only performed
if the `junit` reporter is enabled and the reporter's `outputDir` option
is not an absolute path.

Author: clydin

packages/angular/build/src/builders/karma/application_builder.ts

@@ -577,6 +577,35 @@ async function initializeApplication(
   parsedKarmaConfig.reporters ??= [];
   parsedKarmaConfig.reporters.push(AngularPolyfillsPlugin.NAME);
 
+  // Adjust karma junit reporter outDir location to maintain previous (devkit) behavior
+  // The base path for the reporter was previously the workspace root.
+  // To keep the files in the same location, the reporter's output directory is adjusted
+  // to be relative to the workspace root when using junit.
+  if (parsedKarmaConfig.reporters?.some((reporter) => reporter === 'junit')) {
+    if ('junitReporter' in parsedKarmaConfig) {
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      const junitReporterOptions = (parsedKarmaConfig as any)['junitReporter'] as {
+        outputDir?: unknown;
+      };
+      if (junitReporterOptions.outputDir == undefined) {
+        junitReporterOptions.outputDir = context.workspaceRoot;
+      } else if (
+        typeof junitReporterOptions.outputDir === 'string' &&
+        !path.isAbsolute(junitReporterOptions.outputDir)
+      ) {
+        junitReporterOptions.outputDir = path.join(
+          context.workspaceRoot,
+          junitReporterOptions.outputDir,
+        );
+      }
+    } else {
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      (parsedKarmaConfig as any)['junitReporter'] = {
+        outputDir: context.workspaceRoot,
+      };
+    }
+  }
+
   // When using code-coverage, auto-add karma-coverage.
   // This was done as part of the karma plugin for webpack.
   if (

tests/legacy-cli/e2e/tests/test/karma-junit-output.ts

@@ -0,0 +1,27 @@
+import { expectFileMatchToExist, replaceInFile } from '../../utils/fs';
+import { installPackage } from '../../utils/packages';
+import { silentNg } from '../../utils/process';
+
+const E2E_CUSTOM_LAUNCHER = `
+  customLaunchers: {
+    ChromeHeadlessNoSandbox: {
+      base: 'ChromeHeadless',
+      flags: ['--no-sandbox', '--headless', '--disable-gpu', '--disable-dev-shm-usage'],
+    },
+  },
+  restartOnFileChange: true,
+`;
+
+export default async function () {
+  await installPackage('karma-junit-reporter');
+  await silentNg('generate', 'config', 'karma');
+
+  await replaceInFile('karma.conf.js', 'karma-jasmine-html-reporter', 'karma-junit-reporter');
+  await replaceInFile('karma.conf.js', `'kjhtml'`, `'junit'`);
+
+  await replaceInFile('karma.conf.js', `restartOnFileChange: true`, E2E_CUSTOM_LAUNCHER);
+
+  await silentNg('test', '--no-watch');
+
+  await expectFileMatchToExist('.', /TESTS\-.+\.xml/);
+}