Does fakeAsync guarantee promise completion after tick/flushMicroservice

Main issue is how to test that expected actions were performed once a Promise was completed, for example to test if a component correctly updates its states after receiving some remote content.

In the specs below, the dealWithIt() simulates a logic performed in response to a completed promise (it updates variable and trigger "another async event").

it('Promises fulfilled by flushMicrotasks',fakeAsync((): void => {

    let x = 1;
    let y = 2;

    let dealWithIt = function(p:Promise<number>) {
        p.then( v => {
            x = v;
            Promise.resolve(v).then( v=> {y = v+1; });
        });
    };

    let p = Promise.resolve(y);

    dealWithIt(p);

    flushMicrotasks();
    //valid if promise handling completed
    expect(x).toBe(2);
    expect(y).toBe(3);


}));

it('Promises fulfilled by tick',fakeAsync((): void => {
    let x = 1;
    let y = 2;

    let dealWithIt = function(p:Promise<number>) {
        p.then( v => {
            x = v;
            Promise.resolve(v).then( v=> {y = v+1; });
        });
    };

    let p = Promise.resolve(y);

    dealWithIt(p);

    tick();
    //valid if promise handling completed

    expect(x).toBe(2);
    expect(y).toBe(3);

}));

And both tests pass. At the time of checking expectations the promise was dealt with correctly.

But, is it guaranteed? Or was I just lucky.

Are there any limitations, will all Promises created in the scope of fakeAsync be 'fired' by calling tick or flushMicrotasks.