NewFakeClock returns a FakeClock implementation which can be manually advanced through time for testing.

NewFakeClockAt returns a FakeClock initialised at the given time.Time.

NewRealClock returns a Clock which simply delegates calls to the actual time package; it should be used by packages in production.

Clock provides an interface that packages can use instead of directly using the time module, so that chronology-related behavior can be tested.

FakeClock provides an interface for a clock which can be manually advanced through time.