tick()

Simulates the asynchronous passage of time for the timers in the fakeAsync zone. The microtasks queue is drained at the very start of this function and after any timer callback has been executed.

describe('this test', () => {
  it('looks async but is synchronous', <any>fakeAsync((): void => {
       let flag = false;
       setTimeout(() => {
         flag = true;
       }, 100);
       expect(flag).toBe(false);
       tick(50);
       expect(flag).toBe(false);
       tick(50);
       expect(flag).toBe(true);
     }));
});