Does NestJS Work With Jest?

Fully CompatibleLast verified: 2026-02-20

NestJS and Jest work together seamlessly with official integration and excellent tooling support.

Quick Facts

Compatibility

full

Setup Difficulty

Easy

Official Integration

Yes ✓

Confidence

high

Minimum Versions

NestJS: 8.0.0

Jest: 27.0.0

How NestJS Works With Jest

NestJS has built-in Jest support through the `@nestjs/testing` module, which provides utilities like `Test.createTestingModule()` for constructing isolated test environments. The framework's dependency injection system integrates perfectly with Jest's module mocking capabilities, allowing you to mock services, repositories, and external dependencies with minimal boilerplate. When you scaffold a NestJS project with the CLI, Jest is pre-configured with appropriate TypeScript support, module aliases, and coverage settings. The testing experience is streamlined: you create a testing module that mirrors your application's module structure, override providers with test doubles, and then test your controllers, services, and resolvers in complete isolation. This makes unit testing NestJS applications significantly cleaner than working with other Node frameworks.

Best Use Cases

→Unit testing NestJS services and controllers with mocked dependencies

→Testing database interactions with in-memory databases or mocked repositories

→Integration tests for HTTP endpoints using supertest with NestJS test modules

→GraphQL resolver testing with mocked data sources and authentication

Quick Setup

bash

npm install --save-dev @nestjs/testing jest @types/jest ts-jest

typescript

import { Test, TestingModule } from '@nestjs/testing';
import { CatsService } from './cats.service';
import { CatsController } from './cats.controller';

describe('CatsController', () => {
  let controller: CatsController;
  let service: CatsService;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      controllers: [CatsController],
      providers: [
        {
          provide: CatsService,
          useValue: {
            findAll: jest.fn().mockResolvedValue([{ id: 1, name: 'Fluffy' }]),
          },
        },
      ],
    }).compile();

    controller = module.get<CatsController>(CatsController);
    service = module.get<CatsService>(CatsService);
  });

  it('should return an array of cats', async () => {
    expect(await controller.findAll()).toEqual([{ id: 1, name: 'Fluffy' }]);
    expect(service.findAll).toHaveBeenCalled();
  });
});

Known Issues & Gotchas

warning

TypeScript path aliases not resolving in tests without proper jest.config.js configuration

Fix: Ensure moduleNameMapper is configured in jest.config.js to match tsconfig.json paths, or use the @nestjs/cli which handles this automatically

warning

Async module initialization and lifecycle hooks not executing in tests

Fix: Call await app.init() after createTestingModule to ensure all async initializers and onModuleInit hooks run

critical

Database connections persisting between test suites, causing test pollution

Fix: Use beforeAll/afterAll hooks to connect/disconnect, or better, use a test database that's wiped between test files

Alternatives

•Vitest with NestJS - faster alternative with native ESM support and similar API
•Mocha + Chai with NestJS - more traditional Node.js testing, requires manual setup
•TypeORM with Sinon mocking - database-focused testing without Jest's module system

Resources

docsNestJS Testing Documentation docsJest Official Documentation docsNestJS CLI - Project Setup

Related Compatibility Guides

Django + Jest NestJS + UploadThing NestJS + Resend NestJS + Playwright NestJS + GraphQL NestJS + Payload CMS

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