在spec.ts Angular4中获取类元素的长度

Question

I have a simple spec.ts, where i am getting an array from service. Same service render a table in *ngFor inside the component. Table- tr has a class .dataTr . How can i know how much tr are in the table.

I tried this.

it('Should increase page number on paginator next Click', async(() => {   

    fixture.detectChanges();
    fixture.whenStable().then(() => { 
        fixture.detectChanges();
        console.log(component.dataSource.length);
        let tr = fixture.debugElement.query(By.css('.dataTr'))[1];
        console.log(tr);
        expect(2 + 2).toBe(4);
    });


}));

Answer 1

let numTrs = fixture.debugElement.queryAll(By.css('tr')).length;
expect(numTrs).toBe(/* Expected Number */);

or if you want to search only within the table:

let tableDe = fixture.debugElement.query(By.css('.dataTr'));
expect(tableDe.queryAll(By.css('tr')).length).toBe(/* Expected Number */);