NestJS NestJS Testing & Debugging 2

Question 1

Which library does NestJS recommend for making HTTP requests in end-to-end (e2e) tests?

Accepted Answer

supertest

Answer

axios

Answer

node-fetch

Answer

got

Question 2

In a NestJS e2e test, how do you initialize the application before running tests?

Accepted Answer

Call `NestFactory.create()` and `app.init()` inside `beforeAll()`

Answer

Call `Test.createTestingModule().compile()` without calling `init()`

Answer

Import the AppModule directly and call its constructor

Answer

Use `jest.setup()` to bootstrap the app globally

Question 3

What should be called in `afterAll()` at the end of a NestJS e2e test suite?

Accepted Answer

app.close()

Answer

app.destroy()

Answer

app.shutdown()

Answer

app.terminate()

Question 4

How do you override a provider in a NestJS `TestingModule` with a custom mock?

Accepted Answer

builder.overrideProvider(RealService).useValue(mockService)

Answer

module.providers.replace(RealService, MockService)

Answer

module.set(RealService, mockService)

Answer

jest.mock('./real.service')

Question 5

What does `jest.spyOn(service, 'methodName')` allow you to do in a NestJS test?

Accepted Answer

Wrap the real method to track calls while still executing the original

Answer

Replace the method permanently with a mock function

Answer

Throw an error whenever the method is called

Answer

Automatically generate parameter types from TypeScript metadata

Question 6

When testing a NestJS service that uses a repository (TypeORM), what is the correct token to use with `getRepositoryToken(Entity)` in the test providers array?

Accepted Answer

The result of `getRepositoryToken(Entity)` from `@nestjs/typeorm`

Answer

The Entity class reference itself

Answer

The string 'EntityRepository'

Answer

The string injected via `@InjectRepository()`

Question 7

Which Jest configuration option in `jest.config.js` tells Jest how to handle TypeScript files in a NestJS project?

Accepted Answer

transform: { '^.+\.(t|j)s$': 'ts-jest' }

Answer

transform: { '^.+\.ts$': 'babel-jest' }

Answer

preset: 'ts-node'

Answer

moduleFileExtensions: ['ts', 'js']