Testing

Like @nestjs/mongoose (see the testing section) nestjs-typegoose's forFeature and forRoot rely on a database connection to work. To unit test your CatService without connecting to a mongo database you need to create a fake model using a custom provider.

import { getModelToken } from "nestjs-typegoose";

@Module({
  ProductService,
  {
    provide: getModelToken('Product'),
    useValue: fakeProductModel
  }
})

In a spec file this would look like:

const fakeProductModel = jest.fn();

const module: TestingModule = await Test.createTestingModule({
  providers: [
    {
      provide: getModelToken("Product"),
      useValue: fakeProductModel
    },
    ProductService
  ]
}).compile();

The string given to getModelToken function should be the class name of the typegoose model that you are testing.