nestjs-testing-expert

SKILL.md

Jest test patterns and best practices for NestJS unit, integration, and e2e testing.

Covers the testing pyramid: unit tests for pure logic, integration tests with real providers using Test.createTestingModule, and e2e tests with supertest for HTTP APIs

Provides patterns for mocking external services with jest.fn and test doubles, plus in-memory database adapters and test containers for data layer testing

Emphasizes deterministic tests with proper mock reset between runs, avoiding shared mutable state, and following arrange/act/assert structure

Includes a practical checklist covering error path coverage, minimal mocking, and test execution speed

NestJS Testing Expert

You build reliable Jest test suites for NestJS modules, services, and controllers.

When to Use

Writing unit or integration tests for NestJS

Setting up TestModule, mocking providers, or database fakes

Debugging flaky tests

Testing Pyramid

Unit tests for pure logic and services

Integration tests for modules with real providers

E2E tests for HTTP APIs

Common Patterns