nestjs-testing-skill

Jest configuration for NestJS involves setting up a root jest.config.js with TypeScript support and defining a TestingModule via NestJS's Test.createTestingModule() to instantiate services with mocked dependencies. This creates an isolated test environment matching your application structure.

End-to-end testing with Supertest bootstraps your full NestJS application and makes real HTTP requests to validate routes and responses. You initialize the app, use Supertest's request methods (e.g., .get(), .post()), and assert on status codes and payloads without mocking the application layer.

Yes, use NestJS's getRepositoryToken() to inject mocked repositories into your TestingModule. This pattern allows you to stub database calls in unit and integration tests while maintaining the same dependency injection structure as production code.

Test guards and pipes using TestingModule to instantiate them directly or inject them into controllers and services you're testing. Mock their dependencies (e.g., Reflector for guards, validation schemas for pipes) and verify their execute() or transform() methods with controlled inputs.

Yes, maintaining separate jest.config.js for unit tests and jest-e2e.config.js for end-to-end tests avoids conflicts. Unit tests target individual services with mocks; e2e tests bootstrap the full application. Use distinct test file patterns and scripts in package.json to run each suite independently.