public void GetId_Get65536OrLessIds_NoDelay(int numberOfIds) { // Arrange // When delay is called, start moving the millisecond timer. _timingProvider.When(x => x.DelayMilliseconds(Arg.Any <int>())) .Do(arg => _wasDelayed = true); _timingProvider.GetNowMilliseconds() .ReturnsForAnyArgs(x => _wasDelayed ? ++_nowMilliseconds : _nowMilliseconds); // Act Int128 id = null; for (int i = 0; i < numberOfIds; i++) { id = _generator.GenId(); } // Assert _timingProvider.DidNotReceiveWithAnyArgs().DelayMilliseconds(Arg.Any <int>()); Assert.That(id?.Lo & 0xffff, Is.EqualTo(numberOfIds - 1), "Count part of ID"); }