Why testing ensures application reliability in NestJS - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the testing module in a NestJS test file.

NestJS

import { Test, TestingModule } from '[1]';

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A@nestjs/testing

Bnestjs/core

C@nestjs/common

Dnestjs/platform-express

Attempts:

3 left

💡 Hint

Common Mistakes

Importing from '@nestjs/common' instead of '@nestjs/testing'.

Using 'nestjs/core' which is not for testing.

The '@nestjs/testing' package provides utilities to create testing modules in NestJS.

2fill in blank

medium

Complete the code to create a testing module for the AppService.

NestJS

const module: TestingModule = await Test.createTestingModule({ providers: [[1]] }).compile();

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AAppService

BAppController

CHttpService

DConfigService

Attempts:

3 left

💡 Hint

Common Mistakes

Providing the controller instead of the service.

Providing unrelated services.

The testing module should provide the service you want to test, here 'AppService'.

3fill in blank

hard

Fix the error in the test by completing the code to get the service instance.

NestJS

const service = module.[1](AppService);

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Afetch

Bfind

Cget

Dretrieve

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'find' which is not a method on TestingModule.

Using 'fetch' or 'retrieve' which do not exist here.

The 'get' method retrieves an instance of the provider from the testing module.

4fill in blank

hard

Fill both blanks to write a simple test that checks if the service is defined.

NestJS

it('should be defined', () => { expect(service).[1](); });

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AtoBeFalsy

BtoBeTruthy

CtoBeNull

DtoBeDefined

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'toBeNull' which checks for null, not existence.

Using 'toBeFalsy' which checks for false-like values.

The 'toBeDefined' matcher checks that the value is not undefined.

5fill in blank

hard

Fill all three blanks to write a test that checks the service returns the expected string.

NestJS

it('should return "Hello World!"', () => { expect(service.[1]()).[2]([3]); });

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AgetHello

BtoEqual

C"Hello World!"

DtoBe

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'toBe' which is stricter and may fail for strings.

Using wrong method names or string values.

The test calls 'getHello', expects the result to equal the string 'Hello World!'.