Zimic

import { type HttpSchema } from 'zimic/http';
import { httpInterceptor } from 'zimic/interceptor/http';

// 1. Declare your types
interface User {
  username: string;
}

interface RequestError {
  message: string;
}

// 2. Declare your HTTP schema
// https://bit.ly/zimic-interceptor-http-schemas
type MySchema = HttpSchema<{
  '/users': {
    POST: {
      request: { body: User };
      response: {
        201: { body: User }; // User create
        400: { body: RequestError }; // Bad request
        409: { body: RequestError }; // Conflict
      };
    };
    GET: {
      request: {
        headers: { authorization?: string };
        searchParams: { username?: string; limit?: `${number}` };
      };
      response: {
        200: { body: User[] }; // Users listed
        400: { body: RequestError }; // Bad request
        401: { body: RequestError }; // Unauthorized
      };
    };
  };
}>;

// 3. Create your interceptor
// https://bit.ly/zimic-interceptor-http#httpinterceptorcreateoptions
const myInterceptor = httpInterceptor.create<MySchema>({
  type: 'local',
  baseURL: 'http://localhost:3000',
  saveRequests: true, // Allow access to `handler.requests()`
});

// 4. Manage your interceptor lifecycle
// https://bit.ly/zimic-guides-testing
beforeAll(async () => {
  // 4.1. Start intercepting requests
  // https://bit.ly/zimic-interceptor-http#http-interceptorstart
  await myInterceptor.start();
});

afterEach(() => {
  // 4.2. Clear interceptors so that no tests affect each other
  // https://bit.ly/zimic-interceptor-http#http-interceptorclear
  myInterceptor.clear();
});

afterAll(async () => {
  // 4.3. Stop intercepting requests
  // https://bit.ly/zimic-interceptor-http#http-interceptorstop
  await myInterceptor.stop();
});

// Enjoy mocking!
test('should list users', async () => {
  const users: User[] = [{ username: 'diego-aquino' }];
  const token = 'my-token';

  // 7. Declare your mocks
  // https://bit.ly/zimic-interceptor-http#http-interceptormethodpath
  const listHandler = myInterceptor
    .get('/users')
    // 7.1. Use restrictions to make declarative assertions and narrow down your mocks
    // https://bit.ly/zimic-interceptor-http#http-handlerwithrestriction
    .with({
      headers: { authorization: `Bearer ${token}` },
    })
    .with({
      searchParams: { username: 'diego' },
      exact: true,
    })
    // 7.2. Respond with your mock data
    // https://bit.ly/zimic-interceptor-http#http-handlerresponddeclaration
    .respond({ status: 200, body: users });

  // 8. Run your application and make requests
  const fetchedUsers = await myApplication.fetchUsers({
    token,
    filters: { username: 'diego' },
  });
  expect(fetchedUsers).toEqual(users);

  // 9. Assert yours requests
  // https://bit.ly/zimic-interceptor-http#http-handlerrequests
  const listRequests = listHandler.requests();
  expect(listRequests).toHaveLength(1);

  // The following assertions are automatically checked by the declared
  // restrictions and thus are not necessary. Requests not matching them will
  // cause warnings and not be intercepted by default.

  // If you are not using restrictions, asserting the requests manually is
  // a good practice:
  expect(listRequests[0].headers.get('authorization')).toBe(`Bearer ${token}`);

  expect(listRequests[0].searchParams.size).toBe(1);
  expect(listRequests[0].searchParams.get('username')).toBe('diego');
});