OverrideByFactoryOptions

Kind: Interface

Source: packages/testing/interfaces/override-by-factory-options.interface.ts

Part of: Testing

OverrideByFactoryOptions configures a testing override that creates a replacement provider through a factory function. The inject array declares the dependencies passed to the factory, allowing test modules to compose mocks or custom implementations from other registered providers.

Properties

Diagram

mermaid
graph LR
  A[Test Module] --> B[OverrideByFactoryOptions]
  B --> C[factory(...args)]
  D[inject tokens] --> E[Resolved dependencies]
  E --> C
  C --> F[Replacement provider instance]

Usage

ts
import { Test } from '@nestjs/testing';

const mockUsersService = {
  findAll: jest.fn().mockResolvedValue([]),
};

const moduleRef = await Test.createTestingModule({
  providers: [UsersService, ConfigService],
})
  .overrideProvider(UsersService)
  .useFactory({
    inject: [ConfigService],
    factory: (configService: ConfigService) => ({
      ...mockUsersService,
      findAll: jest.fn().mockResolvedValue([
        { id: 1, environment: configService.get('NODE_ENV') },
      ]),
    }),
  })
  .compile();

AI Coding Instructions

• Use factory when an override needs to be built dynamically from other providers instead of returning a fixed mock.
• Include every factory dependency in inject and keep the array order aligned with the factory function parameters.
• Return the complete replacement provider implementation expected by the code under test.
• Prefer stable mock behavior in factories; avoid unnecessary external state or side effects.
• Ensure injected dependency tokens are available in the testing module before compiling it.