[code-infra] Adopt @mui/internal-test-utils

[Janpot]

Makes it possible to iterate faster on this module, the goal is to thin it out and remove unnecessary wrapper APIs.

in this PR I also make emotion optional for createRenderer

[mui-bot]

Bundle size report

Bundle	Parsed size	Gzip size
@base-ui-components/react	0B(0.00%)	0B(0.00%)
@mui/x-charts-pro	0B(0.00%)	0B(0.00%)

Details of bundle changes

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Check out the code infra dashboard for more information about this PR.

[Copilot]

Pull request overview

This PR introduces the @mui/internal-test-utils package to the code-infra repository, consolidating testing utilities to enable faster iteration and development. The package provides a comprehensive suite of test utilities including renderers, matchers, conformance testing, and helper functions for React component testing.

Key Changes

• New test-utils package with complete TypeScript and Vitest configuration
• Custom chai matchers for accessibility, focus, and style assertions
• Conformance testing framework for component consistency
• React Testing Library wrapper with enhanced functionality

Reviewed changes

Copilot reviewed 22 out of 23 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
packages/test-utils/package.json	Package definition with dependencies and exports for the new test utilities
packages/test-utils/tsconfig.json	TypeScript configuration for the test-utils package
packages/test-utils/tsconfig.build.json	Build-specific TypeScript configuration
packages/test-utils/vitest.config.mts	Vitest test configuration with jsdom environment setup
packages/test-utils/src/index.ts	Main entry point exporting all test utilities
packages/test-utils/src/setupVitest.ts	Vitest setup with console error/warning suppression
packages/test-utils/src/setupVitestBrowser.ts	Browser environment setup with Touch API polyfill
packages/test-utils/src/initMatchers.ts	Initializes chai matchers for tests
packages/test-utils/src/initMatchers.test.js	Test suite for custom error/warning matchers
packages/test-utils/src/initPlaywrightMatchers.ts	Playwright-specific matchers for browser testing
packages/test-utils/src/chaiPlugin.ts	Custom chai assertions for accessibility and styling
packages/test-utils/src/chai.types.ts	TypeScript type definitions for custom chai matchers
packages/test-utils/src/createRenderer.tsx	Enhanced React Testing Library renderer with emotion cache
packages/test-utils/src/createRenderer.test.jsx	Tests for the custom renderer functionality
packages/test-utils/src/createDescribe.ts	Utility for creating describe blocks with skip/only support
packages/test-utils/src/describeConformance.tsx	Comprehensive conformance testing framework for components
packages/test-utils/src/components.tsx	Test helper components (ErrorBoundary, RenderCounter)
packages/test-utils/src/focusVisible.ts	Focus management utilities for testing
packages/test-utils/src/flushMicrotasks.ts	Async utility for flushing microtasks
packages/test-utils/src/fireDiscreteEvent.ts	Discrete event firing utilities for React 17/18 compatibility
packages/test-utils/src/env.ts	Environment detection utilities
packages/code-infra/src/eslint/material-ui/config.mjs	ESLint configuration update to support .jsx extension

[oliviertassinari]

Adopt @mui/internal-test-utils
Makes it possible to iterate faster on this module

OK, so @mui/internal-test-utils is currently owned by https://github.com/mui/material-ui.

Intuitively, I would expect https://github.com/mui/base-ui to be where we can iterate the fastest with this logic, because it covers 80%+ of the test cases for this test utils package, and allows an instant deployment experience against those tests. So wouldn't it be the best place to host those internal modules?