NewFakeClock constructs a fake clock set to the provided time.

NewFakePassiveClock returns a new FakePassiveClock.

FakeClock implements clock.Clock, but returns an arbitrary time.

FakePassiveClock implements PassiveClock, but returns an arbitrary time.

IntervalClock implements clock.PassiveClock, but each invocation of Now steps the clock forward the specified duration.

SimpleIntervalClock implements clock.PassiveClock, but each invocation of Now steps the clock forward the specified duration.