How to use the @posva/vuefire-test-helpers.spyOnSnapshotCallback function in @posva/vuefire-test-helpers

it('unbinds previously bound document when overwriting a bound', async () => {
    // Mock c onSnapshot to spy when the callback is called
    const spy = spyOnSnapshotCallback(item)
    await item.update({ baz: 'baz' })
    await d.update({ ref: item })
    // NOTE see #1
    await delay(5)
    expect(spy).toHaveBeenCalledTimes(1)
    await item.update({ baz: 'bar' })
    // make sure things are updating correctly
    expect(vm.d).toEqual({
      ref: { baz: 'bar' },
    })
    // we call update twice to make sure our mock works
    expect(spy).toHaveBeenCalledTimes(2)
    await d.update({ ref: b })
    // NOTE see #1
    await delay(5)

it('unbinds removed properties', async () => {
    // @ts-ignore
    const a: firestore.DocumentReference = db.collection().doc()
    const unbindSpy = spyUnbind(a)
    const callbackSpy = spyOnSnapshotCallback(a)
    const onSnapshotSpy = spyOnSnapshot(a)

    // @ts-ignore
    const item: firestore.DocumentReference = db.collection().doc()
    await a.update({ isA: true })
    await b.update({ isB: true })
    await item.update({ a })

    expect(unbindSpy).toHaveBeenCalledTimes(0)
    expect(callbackSpy).toHaveBeenCalledTimes(0)
    expect(onSnapshotSpy).toHaveBeenCalledTimes(0)
    await bind('item', item)

    expect(unbindSpy).toHaveBeenCalledTimes(0)
    expect(callbackSpy).toHaveBeenCalledTimes(1)
    expect(onSnapshotSpy).toHaveBeenCalledTimes(1)