typeorm-factories

TypeORM Entity factory

The library allows you to create factories for your entities. Useful when unit-testing your NestJS project.

Faker

Library using faker.js for provide fake-data in you factories.

Library has peer dependecy for faker and faker-types libraries, but make sure you have them installed. If you want take help about functions in your IDE, just install @types/faker and faker libraries for yourself.

How to

1. Install library:

   yarn add typeorm-factories or npm install typeorm-factories

2. Library can find factory file everywhere in project folder. But could be better if you can create folder for them:

   Create folder in project root: mkdir factories

3. Create your first factory:

   import * as Faker from 'faker';
   import { define } from 'typeorm-factories';
   import { Task } from '../src/tasks/task.entity';
    
   define(Task, (faker: typeof Faker) => {
     const task = new Task();
    
     task.id = faker.random.uuid();
     task.title = faker.lorem.word();
    
     return task;
   });

   Here we have factory for Task entity. Entity has this interface:

    @Entity({ name: 'tasks' })
    export class Task {
      @PrimaryGeneratedColumn('uuid')
      id: string;
    
      @Column()
      title: string;
   }

4. Use it everywhere:

   In my case i wanted to create unit-testing of my project without database hitting. Just test it on mock data. How?

   Look at my test file for my tasks controller in project:

   For first we need to create mockFactory for repositories. Place this code everywhere you want:

   export type MockType<T> = {
       [P in keyof T]: jest.Mock<{}>;
   };
    
   // @ts-ignore
   export const repositoryMockFactory: () => MockType<Repository<any>> = jest.fn(() => ({
       findOne: jest.fn(entity => entity),
       findOneOrFail: jest.fn(entity => entity),
       // there u can implement another functions of your repositories
   }));

   And lookup to code of test file for my controller

   describe('TasksController', () => {
       let controller: TasksController;
       let repository: MockType<Repository<Task>>;
       
       beforeEach(async () => {
           const module = await Test.createTestingModule({
           imports: [FactoryModule],
           controllers: [TasksController],
           providers: [
              TasksService,
              { provide: getRepositoryToken(Task), useFactory: repositoryMockFactory },
              ],
           }).compile();
           await module.init(); // we are need to wait for module creating, but we inject our factory module to testing module
           
           controller = module.get<TasksController>(TasksController);
           repository = module.get(getRepositoryToken(Task));
       });
           
       describe('getOne', () => {
           it('should return entity', async () => {
               const task = await factory(Task).make();
               repository.findOneOrFail.mockReturnValue(task);
    
               expect(await repository.findOneOrFail(task.id)).toEqual(task);
               expect(repository.findOneOrFail).toBeCalledWith(task.id);
           })
       })
   });

   As you can see, we are create entity by factory via factory() function. After call this we have object of type EntityFactory.

   EnityFactory provide 3 functions:

   • map(callback) - callback will be called for every item in array or solo item when we call make or makeMany functions.
   • makeMany(count, params) - create many objects of your entity. Override default params in original object by passed params from variable.
   • make(params) - create one one entity object and override. About params see above.

Few words

Detailed instructions for use in development. I have not told even half of all the possibilities of this library. If you have a question about the library’s work, you can create Issue. If you have a desire to help me and make the documentation better, contact me. I have some problems with the narration and I think there are people who do it better than me.