angular-unit-test-helper

Angular Unit Test Helper

Helper functions to help write unit tests in Angular using mocks and spies

Goal

Minimal feature set to bridge obvious gaps in jasmine's support of modern JavaScript features. Ideally, I'd like to be using an auto-mocking library, but they don't play well with Angular's TestBed and RxJS\BehaviorSubject.

Here's a great article about auto-mocking libraries: https://hackernoon.com/with-typescript-3-and-substitute-js-you-are-already-missing-out-when-mocking-or-faking-a3b3240c4607.

Example Projects

Check out my sample projects:

• https://github.com/duluca/local-weather-app
• https://github.com/duluca/lemon-mart

Functions

addProperty(object: object, propertyName: string, valueToReturn: object)

When creating a mock object, add a property to that object with a property getter, so you can use a jasmine.spyOnProperty.

Usage

  weatherServiceMock = jasmine.createSpyObj('WeatherService', ['getCurrentWeather'])
  addPropertyAsBehaviorSubject(weatherServiceMock, 'currentWeather', null)
  ...
  spyOnProperty(weatherServiceMock, 'currentWeather$').and.returnValue({ temp = 72})

addPropertyAsBehaviorSubject(object: object, propertyName: string)

Convenience method to configure a property as a BehaviorSubject, so you can update its value before each test by calling .next on it.

Usage

  weatherServiceMock = jasmine.createSpyObj('WeatherService', ['getCurrentWeather'])
  addPropertyAsBehaviorSubject(weatherServiceMock, 'currentWeather$')
  ...
  weatherServiceMock.currentWeather$.next(fakeWeather)

createComponentMock(className: string, selectorName?: string)

Creates a mock class decorated with @Component, if not specified selector is inferred to be MyClassComponent -> app.

Replaces boilerplate

@Component({
  selector: 'app-current-weather',
  template: '',
})
class MockCurrentWeatherComponent {}

Usage

TestBed.configureTestingModule({
      declarations: [ ..., createComponentMock('CurrentWeatherComponent')]
      ...
})

Inferred selector in the above example is 'app-current-weather'.