Angular Unit test Cannot read properties of null

Question

I have a slider toggle in my page and also a label text. I am writing test cases for that. But Iam getting "cannot read properties of null"

<div class="test" *ngIf="checked">
<div class="toggles">
<mat-slide-toggle [(ngModel)]="checked">Toggle1</mat-slide-toggle>
</div>
</div>

test cases

it('load slide text', ()=> {
component.checked = true;
const togtext = fixture.debugElement.nativeElement.querySelector('mat-slide-toggle') as HTMLElement;
expect(togtext.nativeElement.innerText).toContain('Toggle1');
});

Answer 1

I got the fix, when I moved my if condition to beforeeach

beforeEach(() => {
 TestBed.configureTestingModule({
   declarations: [ParagraphComponent],
   imports: [MatSlideToggleModule, FormsModule],
});
 fixture = 
 TestBed.createComponent(YourComponent);
 component = fixture.componentInstance;
 component.checked = true;

 fixture.detectChanges();
});

it('load slide text', () => {

fixture.detectChanges();
const togtext = fixture.debugElement.nativeElement.querySelector('mat-slide-toggle');

expect(togtext.innerText).
toContain('Toggle1');
});