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angularjasminebind
Teoman shipahi
Teoman shipahi

Reputation: 23102

Angular 8, jasmine <spyOn> : could not find an object to spy upon for bind()

For my Angular component, I have a base class, and in order to keep current this context I have following binding code. If I console.log, I can see updatePreference is called, but jasmine cannot detect if it is called.

If I use following, I am getting error at the title

spyOn(fixture.componentInstance.updatePreference.prototype, 'bind').and.callThrough();

Is there anything missing on my setup?

Profile-component.ts extends Profile-base.ts

public ngOnInit(): void {
    this.updatePreference = this.updatePreference.bind(this);
}

 public openRemovePanel(itemGuid: string) {
    super.openRemovePanel(itemGuid, this.updatePreference);
  }

Profile-base.ts (base class)

public openRemovePanel(itemGuid: string, callbackFunction: (id: string, data: string) => void) { 
….
callbackFunction(id, data);
}

Profile-component.spec.ts

fit('this should work', () => {
let fixture = TestBed.createComponent(ProfileComponent);
fixture.detectChanges();

// tried both of the following
spyOn(fixture.componentInstance.updatePreference.prototype, 'bind').and.callThrough();
spyOn(fixture.componentInstance, updatePreference).and.callThrough();

…...
// make a call to openRemovePanel, and that triggers updatePreference
……

// this does not work
expect(fixture.componentInstance.updatePreference).toHaveBeenCalled();
})

Upvotes: 2

Views: 1460

Answers (1)

Teoman shipahi
Teoman shipahi

Reputation: 23102

After some try and fail, I noticed it works if I re-arrange order like below

let fixture = TestBed.createComponent(ProfileComponent);

// hold the spy reference
let spyReference = spyOn(fixture.componentInstance, updatePreference).and.callThrough();

// then trigger OnInit to do binding  
fixture.detectChanges();

// then write your expection against spy reference
expect(spyReference ).toHaveBeenCalledWith('123', '456');

Upvotes: 2

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