Fake,Spy,Stub, Mock

classes.js

const Database = {
  findAll() {}
}

class UsersController {
  constructor(Database) {
    this.Database = Database;
  }

  getAll() {
    return this.Database.findAll('users');
  }
}

fakes.js

describe('UsersController getAll()', () => {
  it('should return a list of users', () => {
    const expectedDatabaseResponse = [{
      id: 1,
      name: 'John Doe',
      email: '[email protected]'
    }];

    const fakeDatabase = {
      findAll() {
        return expectedDatabaseResponse;
      }
    }
    const usersController = new UsersController(fakeDatabase);
    const response = usersController.getAll();

    expect(response).to.be.eql(expectedDatabaseResponse);
  });
});

mocks.js

describe('UsersController getAll()', () => {
  it('should call database with correct arguments', () => {
    const databaseMock = sinon.mock(Database);
    databaseMock.expects('findAll').once().withArgs('users');

    const usersController = new UsersController(Database);
    usersController.getAll();

    databaseMock.verify();
    databaseMock.restore();
  });
});

spies.js

describe('UsersController getAll()', () => {
  it('should findAll users from database with correct parameters', () => {
    const findAll = sinon.spy(Database, 'findAll');

    const usersController = new UsersController(Database);
    usersController.getAll();

    sinon.assert.calledWith(findAll, 'users');
    findAll.restore();
  });
});

stubs.js

describe('UsersController getAll()', () => {
  it('should return a list of users', () => {
    const expectedDatabaseResponse = [{
      id: 1,
      name: 'John Doe',
      email: '[email protected]'
    }];

    const findAll = sinon.stub(Database, 'findAll');
    findAll.withArgs('users').returns(expectedDatabaseResponse);

    const usersController = new UsersController(Database);
    const response = usersController.getAll();

    sinon.assert.calledWith(findAll, 'users');
    expect(response).to.be.eql(expectedDatabaseResponse);
    findAll.restore();
  });
});