NestJS NestJS Testing & Debugging

Question 1

Which testing framework does NestJS use by default for unit and integration tests?

Accepted Answer

Jest

Answer

NestJS uses Jest as its default testing framework, which is pre-configured when you scaffold a project with the Nest CLI.

Question 2

What is the primary purpose of `Test.createTestingModule()` in NestJS?

Accepted Answer

To create an isolated module context for testing

Answer

`Test.createTestingModule()` creates an isolated NestJS module environment that mirrors the real DI container, allowing you to test components in isolation.

Question 3

Which package must be imported to use `Test.createTestingModule()` in a NestJS test file?

Accepted Answer

@nestjs/testing

Answer

`Test` and `TestingModule` are exported from the `@nestjs/testing` package, which is the dedicated testing utility package for NestJS.

Question 4

Which method must be called after `Test.createTestingModule()` to finalize the module for use in tests?

Accepted Answer

.compile()

Answer

`.compile()` resolves the module's dependency injection tree and returns a `TestingModule` instance ready for retrieving providers and controllers.

Question 5

How do you retrieve a provider instance from a compiled `TestingModule` in NestJS?

Accepted Answer

module.get(ServiceClass)

Answer

`module.get(ServiceClass)` retrieves a singleton instance of the specified provider from the module's DI container.

NestJS Practice Test

NestJS Practice Test

NestJS NestJS Testing & Debugging