fix(@angular/build): enhance Vitest config merging and validation

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

@@ -40,7 +40,7 @@ interface VitestConfigPluginOptions {
   projectSourceRoot: string;
   reporters?: string[] | [string, object][];
   setupFiles: string[];
-  projectPlugins: VitestPlugins;
+  projectPlugins: Exclude<UserWorkspaceConfig['plugins'], undefined>;
   include: string[];
 }
 
@@ -73,13 +73,56 @@ export function createVitestConfigPlugin(options: VitestConfigPluginOptions): Vi
     async config(config) {
       const testConfig = config.test;
 
+      if (testConfig?.projects?.length) {
+        this.warn(
+          'The "test.projects" option in the Vitest configuration file is not supported. ' +
+            'The Angular CLI Test system will construct its own project configuration.',
+        );
+        delete testConfig.projects;
+      }
+
+      if (testConfig?.include) {
+        this.warn(
+          'The "test.include" option in the Vitest configuration file is not supported. ' +
+            'The Angular CLI Test system will manage test file discovery.',
+        );
+        delete testConfig.include;
+      }
+
+      // The user's setup files should be appended to the CLI's setup files.
+      const combinedSetupFiles = [...setupFiles];
+      if (testConfig?.setupFiles) {
+        if (typeof testConfig.setupFiles === 'string') {
+          combinedSetupFiles.push(testConfig.setupFiles);
+        } else if (Array.isArray(testConfig.setupFiles)) {
+          combinedSetupFiles.push(...testConfig.setupFiles);
+        }
+        delete testConfig.setupFiles;
+      }
+
+      // Merge user-defined plugins from the Vitest config with the CLI's internal plugins.
+      if (config.plugins) {
+        const userPlugins = config.plugins.filter(
+          (plugin) =>
+            // Only inspect objects with a `name` property as these would be the internal injected plugins
+            !plugin ||
+            typeof plugin !== 'object' ||
+            !('name' in plugin) ||
+            (!plugin.name.startsWith('angular:') && !plugin.name.startsWith('vitest')),
+        );
+
+        if (userPlugins.length > 0) {
+          projectPlugins.push(...userPlugins);
+        }
+      }
+
       const projectResolver = createRequire(projectSourceRoot + '/').resolve;
 
       const projectConfig: UserWorkspaceConfig = {
         test: {
           ...testConfig,
           name: projectName,
-          setupFiles,
+          setupFiles: combinedSetupFiles,
           include,
           globals: testConfig?.globals ?? true,
           ...(browser ? { browser } : {}),
@@ -99,6 +142,7 @@ export function createVitestConfigPlugin(options: VitestConfigPluginOptions): Vi
           coverage: await generateCoverageOption(options.coverage, projectName),
           // eslint-disable-next-line @typescript-eslint/no-explicit-any
           ...(reporters ? ({ reporters } as any) : {}),
+          ...(browser ? { browser } : {}),
           projects: [projectConfig],
         },
       };

packages/angular/build/src/builders/unit-test/tests/behavior/runner-config-vitest_spec.ts

@@ -88,6 +88,7 @@ describeBuilder(execute, UNIT_TEST_BUILDER_INFO, (harness) => {
       const results = JSON.parse(harness.readFile('vitest-results.json'));
       expect(results.numPassedTests).toBe(1);
     });
+
     it('should allow overriding builder options via runnerConfig file', async () => {
       harness.useTarget('test', {
         ...BASE_OPTIONS,
@@ -142,5 +143,179 @@ describeBuilder(execute, UNIT_TEST_BUILDER_INFO, (harness) => {
       const { result } = await harness.executeOnce();
       expect(result?.success).toBeFalse();
     });
+
+    it('should warn and ignore "test.projects" option from runnerConfig file', async () => {
+      harness.useTarget('test', {
+        ...BASE_OPTIONS,
+        runnerConfig: 'vitest.config.ts',
+      });
+
+      harness.writeFile(
+        'vitest.config.ts',
+        `
+        import { defineConfig } from 'vitest/config';
+        export default defineConfig({
+          test: {
+            projects: ['./foo.config.ts'],
+          },
+        });
+        `,
+      );
+
+      const { result, logs } = await harness.executeOnce();
+      expect(result?.success).toBeTrue();
+
+      // TODO: Re-enable once Vite logs are remapped through build system
+      // expect(logs).toContain(
+      //   jasmine.objectContaining({
+      //     level: 'warn',
+      //     message: jasmine.stringMatching(
+      //       'The "test.projects" option in the Vitest configuration file is not supported.',
+      //     ),
+      //   }),
+      // );
+    });
+
+    it('should warn and ignore "test.include" option from runnerConfig file', async () => {
+      harness.useTarget('test', {
+        ...BASE_OPTIONS,
+        runnerConfig: 'vitest.config.ts',
+      });
+
+      harness.writeFile(
+        'vitest.config.ts',
+        `
+        import { defineConfig } from 'vitest/config';
+        export default defineConfig({
+          test: {
+            include: ['src/app/non-existent.spec.ts'],
+          },
+        });
+        `,
+      );
+
+      const { result, logs } = await harness.executeOnce();
+      expect(result?.success).toBeTrue();
+
+      // TODO: Re-enable once Vite logs are remapped through build system
+      // expect(logs).toContain(
+      //   jasmine.objectContaining({
+      //     level: 'warn',
+      //     message: jasmine.stringMatching(
+      //       'The "test.include" option in the Vitest configuration file is not supported.',
+      //     ),
+      //   }),
+      // );
+    });
+
+    it(`should append "test.setupFiles" (string) from runnerConfig to the CLI's setup`, async () => {
+      harness.useTarget('test', {
+        ...BASE_OPTIONS,
+        runnerConfig: 'vitest.config.ts',
+      });
+
+      harness.writeFile(
+        'vitest.config.ts',
+        `
+        import { defineConfig } from 'vitest/config';
+        export default defineConfig({
+          test: {
+            setupFiles: './src/app/custom-setup.ts',
+          },
+        });
+        `,
+      );
+
+      harness.writeFile('src/app/custom-setup.ts', `(globalThis as any).customSetupLoaded = true;`);
+
+      harness.writeFile(
+        'src/app/app.component.spec.ts',
+        `
+        import { test, expect } from 'vitest';
+        test('should have custom setup loaded', () => {
+          expect((globalThis as any).customSetupLoaded).toBe(true);
+        });
+        `,
+      );
+
+      const { result } = await harness.executeOnce();
+      expect(result?.success).toBeTrue();
+    });
+
+    it(`should append "test.setupFiles" (array) from runnerConfig to the CLI's setup`, async () => {
+      harness.useTarget('test', {
+        ...BASE_OPTIONS,
+        runnerConfig: 'vitest.config.ts',
+      });
+
+      harness.writeFile(
+        'vitest.config.ts',
+        `
+        import { defineConfig } from 'vitest/config';
+        export default defineConfig({
+          test: {
+            setupFiles: ['./src/app/custom-setup-1.ts', './src/app/custom-setup-2.ts'],
+          },
+        });
+        `,
+      );
+
+      harness.writeFile('src/app/custom-setup-1.ts', `(globalThis as any).customSetup1 = true;`);
+      harness.writeFile('src/app/custom-setup-2.ts', `(globalThis as any).customSetup2 = true;`);
+
+      harness.writeFile(
+        'src/app/app.component.spec.ts',
+        `
+        import { test, expect } from 'vitest';
+        test('should have custom setups loaded', () => {
+          expect((globalThis as any).customSetup1).toBe(true);
+          expect((globalThis as any).customSetup2).toBe(true);
+        });
+        `,
+      );
+
+      const { result } = await harness.executeOnce();
+      expect(result?.success).toBeTrue();
+    });
+
+    it('should merge and apply custom Vite plugins from runnerConfig file', async () => {
+      harness.useTarget('test', {
+        ...BASE_OPTIONS,
+        runnerConfig: 'vitest.config.ts',
+      });
+
+      harness.writeFile(
+        'vitest.config.ts',
+        `
+        import { defineConfig } from 'vitest/config';
+        export default defineConfig({
+          plugins: [
+            {
+              name: 'my-custom-transform-plugin',
+              transform(code, id) {
+                if (code.includes('__PLACEHOLDER__')) {
+                  return code.replace('__PLACEHOLDER__', 'transformed by custom plugin');
+                }
+              },
+            },
+          ],
+        });
+        `,
+      );
+
+      harness.writeFile(
+        'src/app/app.component.spec.ts',
+        `
+        import { test, expect } from 'vitest';
+        test('should have been transformed by custom plugin', () => {
+          const placeholder = '__PLACEHOLDER__';
+          expect(placeholder).toBe('transformed by custom plugin');
+        });
+        `,
+      );
+
+      const { result } = await harness.executeOnce();
+      expect(result?.success).toBeTrue();
+    });
   });
 });