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Given this simple component :
import { Component} from '@angular/core'; @Component({ selector: 'app-component' }) export class AppComponent { foo() { this.bar(); } bar() { console.log('hello'); } } How come the following test won't validate that bar is called when I call foo
describe('AppComponent', () => { let component: AppComponent; beforeEach(() => { component = new AppComponent(); } it('should foobar', () => { component.foo(); spyOn(component, 'bar'); expect(component.bar).toHaveBeenCalled(); }) } I get the failed test :
Expected spy bar to have been called. 
397
To call another components function in Angular, we can inject the component we want to call the function on as a dependency. export class OneComponent implements OnInit, AfterViewInit { //... ngOnInit() {} public testCall() { alert("I am here.."); } //... }
The question does not ask component interaction, it asks for calling a component method from a service. This simply can be achieved by injecting service to the component. Then define a method inside the service which takes a function as parameter.
fixture is a wrapper for our component's environment so we can control things like change detection. To trigger change detection we call the function fixture.detectChanges() , now we can update our test spec to: Copy it('login button hidden when the user is authenticated', () => { expect(el. nativeElement. textContent.
You need to set up the spy before the method is called. Jasmine spys wrap function to determine when they are called and what they get called with. The method must be wrapped before the spied on method is called in order to capture the information. Try changing your test to match the following:
it('should foobar', () => { spyOn(component, 'bar'); component.foo(); expect(component.bar).toHaveBeenCalled(); }) If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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