Angular SpyOn 公共属性

Question

I need to spy on the public property in angular service. But this property doesn't have getter or setter, therefore, I couldn't spy on that property.

Always get or set is required to use that SpyOn . If I don't provide it, it is set as 'get'. Is there any other way to mock or spy on public property without getter or setter? And why are those methods not available? Am I using an anti-pattern by exposing a public property from service?

This is the code with the public variable that I need to mock:

@Injectable()
export class StudentService {

  public students = [];
  .................

}

Answer 1

You don't need to spy on separate properties, because they don't contain any business logic. One of the purposes of testing is to ensure that functionality works as desired. So you really need to test only methods, and in some cases check on how they affect your properties, eg expect(component.students).equaltTo(mockStudents2) .

Answer 2

I would use jasmine.createSpyObj and then attach it to this object.

Try:

describe('Your component test', () => {
  let mockStudentService: any;

  beforeEach(async(() => {
    mockStudentService = jasmine.createSpyObj('studentService', []); 
    // in the empty array put the public methods you require as strings
    mockStudentService.students = []; // mock the public array you want here
    TestBed.configureTestingModule({
      providers: [{ provide: StudentService, useValue: mockStudentService }],
    }).compileComponents();
  }));
});