testing-expert

A React and NestJS testing strategy defines the scope of unit, integration, and end-to-end tests. It establishes pyramid guidelines, measurable coverage targets, and consistent workflows using tools like Jest, Vitest, and Playwright.

Configuring Jest or Vitest for Next.js involves defining maintainable test patterns aligned with your project structure and CI workflows. You should establish mocks, fixtures, and documentation standards to ensure repeatable, fast tests across your application layers.

Integration tests for NestJS API endpoints use tools like Supertest to cover API interactions. You should use established patterns for test organization and mocks to ensure repeatable, fast tests that validate endpoint behavior within your CI workflows.

React Testing Library is used for unit and integration tests of React components, not end-to-end testing. For E2E tests covering user flows across React and NestJS layers, Playwright or Cypress are the recommended tools.

Unit tests validate individual components or services, while e2e tests validate complete user flows across React and NestJS layers. Combining them improves code quality, reliability, and maintainability by covering isolated logic and full application behavior.