How to use
- Copy the installation command and review the source package before installing it in your own agent environment.
- Check the source document for required tools, credentials and supported hosts.
- Describe your input and desired deliverable; review the output against the source material.
npx skills add https://github.com/j4flmao/agent_skills_nodejs_nestjs --skill testing-nestjs-applicationsBefore you start
- Installation does not include a model subscription, API allowance or permission to access your files.
- Repository stars and installation counts describe activity, not an independent quality or security test.
Original skill document
Rendered from the source repository. Headings, examples, code, tables, links, and referenced images are preserved.
Testing NestJS Applications
When to use
- Writing tests for use cases, controllers, or full HTTP flows
- Setting up test strategy for a NestJS feature
- Replacing mocks with hand-rolled fakes
Core rules
- Unit tests: domain entities with pure assertions (no NestJS testing module)
- Use-cases tested with hand-rolled fakes (not jest.mock)
- Integration tests:
Test.createTestingModulewith real or fake providers - E2E tests: Supertest against bootstrapped app
- No
jest.mockfor internal modules; only for third-party if needed
Reference shape (TypeScript)
Unit Test (Domain Entity)
typescript
import { User } from './user.entity';
describe('User', () => {
it('creates with valid email', () => {
const email = Email.create('test@example.com');
const user = User.create('1', email);
expect(user.id).toBe('1');
});
});Integration Test (Use-Case with Fake)
typescript
import { Test } from '@nestjs/testing';
import { CreateUserUseCase } from './create-user.use-case';
import { FakeUserRepository } from './fakes/fake-user.repository';
describe('CreateUserUseCase', () => {
let useCase: CreateUserUseCase;
beforeEach(async () => {
const module = await Test.createTestingModule({
providers: [
CreateUserUseCase,
{ provide: 'UserRepository', useClass: FakeUserRepository },
],
}).compile();
useCase = module.get(CreateUserUseCase);
});
it('creates user', async () => {
const result = await useCase.execute({ id: '1', email: 'test@example.com' });
expect(result.success).toBe(true);
});
});Examples — Do
typescript
const module = await Test.createTestingModule({
controllers: [UserController],
providers: [CreateUserUseCase, { provide: 'UserRepository', useClass: FakeUserRepository }],
}).compile();Examples — Don't
typescript
// ❌ jest.mock for internal modules
jest.mock('../../application/user.repository');Checklist
- [ ] Domain entities have unit tests
- [ ] Use-cases tested with hand-rolled fakes
- [ ] Integration tests with
Test.createTestingModule - [ ] E2E tests with Supertest
See reference/test-patterns.md for full patterns.
