答案 0 :(得分:2)
试试这个
let hl:HTMLSelectElement = (fixture.debugElement.query(By.css('select')).nativeElement as HTMLSelectElement);
hl.value='newvalue'; //set the new value
hl.dispatchEvent(new Event('change')); //this is what triggers angular to do its magic
fixture.detectChanges();
tick(); //assuming you are doing this inside a fakeAsync
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