Executing a function to erase the stored value in local storage during an Angular unit test

Looking to verify whether the localStorage gets cleared when I execute my function.

Component

ngOnInit() {
    // Logging out when reaching login screen for login purposes
    this.authService.logout();
  }

authService

logout() {
    // Removing logged in user from localStorage
    localStorage.removeItem('currentUser');
  }

TEST

fit('ngOnInit should log out user stored in localStorage', () => {
    // Example data stored as token
    localStorage.setItem('token', 'someUserToken');

    component.ngOnInit();

    expect(localStorage.getItem('token')).toEqual('{}');
});

Is there a method to accomplish this?

Answer №1

When it comes to unit testing, the focus should always be on the specific functionality being tested.

For instance, there is no need to verify if local storage gets cleared in your component's test. That task falls under the responsibility of the authentication service that your component interacts with.

Instead, make sure to verify that the correct method is getting called as expected.

it('ngOnInit should call auth.logout', () => {
    spyOn(component['authService'], 'logout');

    component.ngOnInit();

    expect(component['authService'].logout).toHaveBeenCalled();
});

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