Test database strategies in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the testing module in NestJS.

NestJS

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

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Atests

Btesting

Ctest

Dtest-module

Attempts:

3 left

💡 Hint

Common Mistakes

Using '@nestjs/test' instead of '@nestjs/testing'.

Misspelling the import path as 'tests'.

The correct import path for NestJS testing utilities is '@nestjs/testing'.

2fill in blank

medium

Complete the code to create a testing module with a database provider.

NestJS

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

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ADbConnection

BDatabaseModule

CDatabaseProvider

DDatabaseService

Attempts:

3 left

💡 Hint

Common Mistakes

Using a module like DatabaseModule in the providers array (use imports for modules).

Using an unregistered service or connection name.

In NestJS testing, database services are typically provided by including the service class in the providers array.

3fill in blank

hard

Fix the error in the test setup by completing the database connection string.

NestJS

await module.get(DatabaseProvider).connect([1]);

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A'mongodb://localhost:27017/testdb'

B'mysql://localhost:3306/testdb'

C'postgresql://localhost:5432/testdb'

D'redis://localhost:6379/testdb'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a connection string for a different database type.

Missing quotes around the connection string.

The test database connection string should match the database type used; PostgreSQL is common for NestJS tests with TypeORM.

4fill in blank

hard

Fill both blanks to mock the database service and clear data before each test.

NestJS

jest.mock('[1]');
beforeEach(async () => { await databaseService.[2](); });

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Asrc/database/database.service

Bclear

Csrc/database/database.provider

Dreset

Attempts:

3 left

💡 Hint

Common Mistakes

Mocking the module or provider instead of the service.

Calling a non-existent or wrong method like 'reset' without implementation.

Mock the database service file path with jest.mock and call the 'clear' method on the database service instance before each test to reset state.

5fill in blank

hard

Fill all three blanks to create a test database connection, run migrations, and close connection after tests.

NestJS

await connection.[1]();
await connection.[2]();
afterAll(async () => { await connection.[3](); });

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Aconnect

BrunMigrations

Cclose

Dinitialize

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'initialize' instead of 'connect'.

Forgetting to close the connection in afterAll.

First connect to the test database, run migrations to set up the schema, and close the connection after all tests.