NestJS Testing

import { Test } from "@nestjs/testing";
import { UsersService } from "./users.service";

describe("UsersService", () => {
  let service: UsersService;

  beforeEach(async () => {
    const moduleRef = await Test.createTestingModule({
      providers: [UsersService],
    }).compile();

    service = moduleRef.get<UsersService>(UsersService);
  });

  it("সব users দেয়", () => {
    const users = service.findAll();
    expect(users).toHaveLength(2);
  });

  it("not found-এ exception", () => {
    expect(() => service.findOne(999)).toThrow();
  });
});

import { Test } from "@nestjs/testing";
import { UsersController } from "./users.controller";
import { UsersService } from "./users.service";

describe("UsersController", () => {
  let controller: UsersController;
  let service: { findAll: jest.Mock };

  beforeEach(async () => {
    service = {
      findAll: jest.fn().mockResolvedValue([{ id: 1, name: "রহিম" }]),
    };

    const moduleRef = await Test.createTestingModule({
      controllers: [UsersController],
      providers: [{ provide: UsersService, useValue: service }],
    }).compile();

    controller = moduleRef.get<UsersController>(UsersController);
  });

  it("findAll ডাকা হয়", async () => {
    await controller.findAll();
    expect(service.findAll).toHaveBeenCalled();
  });
});

import { Test, TestingModule } from "@nestjs/testing";
import { INestApplication } from "@nestjs/common";
import * as request from "supertest";
import { AppModule } from "../src/app.module";

describe("App (e2e)", () => {
  let app: INestApplication;

  beforeAll(async () => {
    const moduleFixture: TestingModule = await Test.createTestingModule({
      imports: [AppModule],
    }).compile();

    app = moduleFixture.createNestApplication();
    await app.init();
  });

  afterAll(async () => {
    await app.close();
  });

  it("GET / → Hello", () => {
    return request(app.getHttpServer())
      .get("/")
      .expect(200)
      .expect(/Hello World/);
  });

  it("POST /users → validation fails", () => {
    return request(app.getHttpServer())
      .post("/users")
      .send({ name: "" })
      .expect(400);
  });
});

npm test             # unit tests
npm run test:e2e     # end-to-end
npm run test:cov     # coverage report