Write clean, maintainable pytest tests using Fake-based testing, contract testing, and dependency injection patterns. Use when setting up test suites for Python/MCP projects, creating Fakes for external dependencies, writing contract tests, or implementing test patterns with fixtures and parametrization.

使用基于 Fake 的测试、契约测试和依赖注入模式编写清洁且可维护的 pytest 测试。适用于为 Python/MCP 项目搭建测试套件、为外部依赖创建 Fake、编写契约测试，或结合 fixture 和参数化实现测试模式。