add-todo.component.spec.ts

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [
        AddTodoComponent,
      ],
      imports: [
        FormsModule,
        TranslateModule.forRoot(),
      ],
      providers: [
        SpyHelper.provideMagicalMock(TodoListService)
      ],
      schemas: [NO_ERRORS_SCHEMA]
    })
    .compileComponents();
  }));  

  let todoListServiceMock: jasmine.SpyObj<TodoListService>;
  beforeEach(() => {
    todoListServiceMock = TestBed.get(TodoListService);

    fixture = TestBed.createComponent(AddTodoComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();
  });

  it('should create', () => {
    expect(component).toBeTruthy();
  });

  it('should update todo item when todo item is in todo list', () => {

    // Arrange
    const todoList = [
      { id: 'task1', title: 'Buy Milk', description: 'Remember to buy milk' },
      { id: 'task2', title: 'Go to the gym', description: 'Remember to work out' }
    ];
    (todoListServiceMock as any).todoList = todoList;
    todoListServiceMock.updateTodo.and.returnValue(of([]));

    // Act
    component.currentTODO = todoList[0];
    const form = new NgForm([], []);
    component.save(form);

    // Assert
    expect(todoListServiceMock.updateTodo).toHaveBeenCalledWith(component.currentTODO);
  });

  it('should add new todo item when todo item is not in todo list', () => {
    // Arrange
    const newTodo = { id: 'lala1', title: 'Buy Milk', description: 'Remember to buy milk' };

    const todoList = [
      { id: 'task1', title: 'Buy Milk', description: 'Remember to buy milk' },
      { id: 'task2', title: 'Go to the gym', description: 'Remember to work out' }
    ];
    (todoListServiceMock as any).todoList = todoList;
    todoListServiceMock.addTodo.and.returnValue(of([]));

    // Act
    component.currentTODO = newTodo;
    const form = new NgForm([], []);

    debugger;
    component.save(form);

    // Assert
    expect(todoListServiceMock.addTodo).toHaveBeenCalledWith(newTodo);
  });