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Create factories for your TypeORM entities. Useful for NestJS applications

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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.