fix(@angular/cli): use headless option in MCP test tool

[cexbrayat]

PR Checklist

Please check to confirm your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular-cli/blob/main/CONTRIBUTING.md#-commit-message-guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the new behavior?

This avoids the following error for projects using Vitest and Browser mode:

 Unhandled Error:
  Error: [(chrome)] Browser "chrome" is not supported by the browser provider "playwright". Supported
  browsers: firefox, webkit, chromium.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[gemini-code-assist]

Code Review

This pull request updates the test tool to support the --headless option for the @angular/build:unit-test builder, specifically for Vitest-based projects, while preserving ChromeHeadless for Karma. It includes logic to detect the builder type, updated documentation, and new unit tests. Feedback suggests refactoring the added tests into a parameterized format to reduce duplication.

[gemini-code-assist]

These two new test cases are very similar and contain duplicated logic. To improve maintainability and reduce redundancy, you could consider parameterizing them. This can be done by defining the test cases in an array and iterating over them to create the it blocks dynamically.

  const testCases = [
    {
      description: 'when using Vitest',
      projectName: 'my-vitest-app',
      options: { runner: 'vitest' },
    },
    {
      description: 'when the runner is omitted',
      projectName: 'my-default-vitest-app',
      options: {},
    },
  ];

  for (const { description, projectName, options } of testCases) {
    it('should use the headless option for the unit-test builder ' + description, async () => {
      addProjectToWorkspace(mockContext.workspace.projects, projectName, {
        test: {
          builder: '@angular/build:unit-test',
          options,
        },
      });

      await runTest({ project: projectName }, mockContext);

      expect(mockHost.runCommand).toHaveBeenCalledWith(
        'ng',
        ['test', projectName, '--headless', 'true', '--watch', 'false'],
        { cwd: '/test' },
      );
    });
  }