refactor(@schematics/angular): use .mts extension for generated Vitest configuration

Update the generated Vitest base configuration file extension from `.ts` to `.mts` to ensure it is treated as an ES module by default. This avoids warnings from Vite regarding ESM syntax in CommonJS files when the workspace does not define `"type": "module"`.

Also updates related schematics tests, karma migration hints, and builder integration test specs to use `vitest-base.config.mts`.

Author: alan-agius4

packages/angular/build/src/builders/unit-test/tests/options/isolate_spec.ts

@@ -57,7 +57,7 @@ describeBuilder(execute, UNIT_TEST_BUILDER_INFO, (harness) => {
 
     it('should override isolate from the Vitest config file when set to false', async () => {
       harness.writeFile(
-        'vitest-base.config.ts',
+        'vitest-base.config.mts',
         `
           import { defineConfig } from 'vitest/config';
 

packages/angular/build/src/builders/unit-test/tests/options/runner-config-coverage_spec.ts

@@ -23,7 +23,7 @@ describeBuilder(execute, UNIT_TEST_BUILDER_INFO, (harness) => {
     describe('Vitest Runner', () => {
       it('should preserve thresholds from Vitest config when not overridden by CLI', async () => {
         harness.writeFile(
-          'vitest-base.config.ts',
+          'vitest-base.config.mts',
           `
           import { defineConfig } from 'vitest/config';
           export default defineConfig({
@@ -52,7 +52,7 @@ describeBuilder(execute, UNIT_TEST_BUILDER_INFO, (harness) => {
 
       it('should override Vitest config thresholds with CLI thresholds', async () => {
         harness.writeFile(
-          'vitest-base.config.ts',
+          'vitest-base.config.mts',
           `
           import { defineConfig } from 'vitest/config';
           export default defineConfig({
@@ -84,7 +84,7 @@ describeBuilder(execute, UNIT_TEST_BUILDER_INFO, (harness) => {
 
       it('should merge partial CLI thresholds with Vitest config thresholds', async () => {
         harness.writeFile(
-          'vitest-base.config.ts',
+          'vitest-base.config.mts',
           `
           import { defineConfig } from 'vitest/config';
           export default defineConfig({

packages/angular/build/src/builders/unit-test/tests/options/runner-config_spec.ts

@@ -44,7 +44,7 @@ describeBuilder(execute, UNIT_TEST_BUILDER_INFO, (harness) => {
       });
 
       it('should search for a config file when `true`', async () => {
-        harness.writeFile('vitest-base.config.ts', VITEST_CONFIG_CONTENT);
+        harness.writeFile('vitest-base.config.mts', VITEST_CONFIG_CONTENT);
         harness.useTarget('test', {
           ...BASE_OPTIONS,
           runnerConfig: true,
@@ -57,7 +57,7 @@ describeBuilder(execute, UNIT_TEST_BUILDER_INFO, (harness) => {
       });
 
       it('should ignore config file when `false`', async () => {
-        harness.writeFile('vitest-base.config.ts', VITEST_CONFIG_CONTENT);
+        harness.writeFile('vitest-base.config.mts', VITEST_CONFIG_CONTENT);
         harness.useTarget('test', {
           ...BASE_OPTIONS,
           runnerConfig: false,
@@ -70,7 +70,7 @@ describeBuilder(execute, UNIT_TEST_BUILDER_INFO, (harness) => {
       });
 
       it('should ignore config file by default', async () => {
-        harness.writeFile('vitest-base.config.ts', VITEST_CONFIG_CONTENT);
+        harness.writeFile('vitest-base.config.mts', VITEST_CONFIG_CONTENT);
         harness.useTarget('test', {
           ...BASE_OPTIONS,
         });
@@ -96,9 +96,9 @@ describeBuilder(execute, UNIT_TEST_BUILDER_INFO, (harness) => {
 
       it('should find and use a `vitest-base.config.js` in the workspace root', async () => {
         // This file should be ignored because the new logic looks for `vitest-base.config.*`.
-        harness.writeFile('vitest.config.mts', VITEST_CONFIG_CONTENT);
+        harness.writeFile('vitest.config.ts', VITEST_CONFIG_CONTENT);
         // The workspace root is the directory containing the project root in the test harness.
-        harness.writeFile('vitest-base.config.js', VITEST_CONFIG_CONTENT);
+        harness.writeFile('vitest-base.config.mjs', VITEST_CONFIG_CONTENT);
         harness.useTarget('test', {
           ...BASE_OPTIONS,
           runnerConfig: true,

…fig/files/vitest-base.config.ts.template …ig/files/vitest-base.config.mts.templatepackages/schematics/angular/config/files/vitest-base.config.ts.template renamed to packages/schematics/angular/config/files/vitest-base.config.mts.template packages/schematics/angular/config/files/vitest-base.config.ts.template renamed to packages/schematics/angular/config/files/vitest-base.config.mts.template

@@ -72,7 +72,7 @@ function addVitestConfig(options: ConfigOptions): Rule {
       if (testTarget.options.runner === 'karma') {
         context.logger.warn(
           `The "test" target is configured to use the "karma" runner in the main options.` +
-            ' The generated "vitest-base.config.ts" file may not be used.',
+            ' The generated "vitest-base.config.mts" file may not be used.',
         );
       }
 
@@ -85,14 +85,14 @@ function addVitestConfig(options: ConfigOptions): Rule {
         ) {
           context.logger.warn(
             `The "test" target's "${name}" configuration is configured to use the "karma" runner.` +
-              ' The generated "vitest-base.config.ts" file may not be used for that configuration.',
+              ' The generated "vitest-base.config.mts" file may not be used for that configuration.',
           );
         }
       }
 
       return mergeWith(
         apply(url('./files'), [
-          filter((p) => p.endsWith('vitest-base.config.ts.template')),
+          filter((p) => p.endsWith('vitest-base.config.mts.template')),
           applyTemplates({}),
           move(project.root),
         ]),

packages/schematics/angular/config/index.ts

@@ -194,9 +194,9 @@ describe('Config Schematic', () => {
       applicationTree.overwrite('angular.json', JSON.stringify(angularJson));
     });
 
-    it('should create a vitest-base.config.ts file', async () => {
+    it('should create a vitest-base.config.mts file', async () => {
       const tree = await runConfigSchematic(ConfigType.Vitest);
-      expect(tree.exists('projects/foo/vitest-base.config.ts')).toBeTrue();
+      expect(tree.exists('projects/foo/vitest-base.config.mts')).toBeTrue();
     });
 
     it(`should set 'runnerConfig' in test builder`, async () => {

packages/schematics/angular/config/index_spec.ts

@@ -163,7 +163,7 @@ export async function processKarmaConfig(
       context.logger.warn(
         `Project "${projectName}" uses a custom Karma configuration file "${karmaConfig}". ` +
           `Tests have been migrated to use Vitest, but you may need to manually migrate custom settings ` +
-          `from this Karma config to a Vitest config (e.g. "vitest-base.config.ts") ` +
+          `from this Karma config to a Vitest config (e.g. "vitest-base.config.mts") ` +
           `and set the "runnerConfig" option to true.`,
       );
       manualMigrationFiles.push(karmaConfig);

packages/schematics/angular/migrations/migrate-karma-to-vitest/karma-processor.ts

@@ -10,9 +10,9 @@ export default async function (): Promise<void> {
 
   await ng('generate', 'component', 'my-comp');
 
-  // Create vitest-base.config.ts
+  // Create vitest-base.config.mts
   await writeFile(
-    'vitest-base.config.ts',
+    'vitest-base.config.mts',
     `
       import { defineConfig } from 'vitest/config';
       import { playwright } from '@vitest/browser-playwright';

tests/e2e/tests/vitest/browser-custom-config.ts

@@ -47,7 +47,7 @@ export async function applyVitestBuilder(options?: {
     }
   });
 
-  await installWorkspacePackages();
+  await installWorkspacePackages({ force: true });
 
   await updateJsonFile('angular.json', (json) => {
     const projects = Object.values(json['projects']);