### Question:
MonotonicClock implements Clock { @Override public long nanoTime() { return clock.nanoTime(); } private  MonotonicClock(Clock clock, long epochNanos, long nanoTime); static MonotonicClock create(Clock clock); @Override long now(); @Override long nanoTime();  }### Answer:
@Test void nanoTime() { assertThat(testClock.now()).isEqualTo(EPOCH_NANOS); MonotonicClock monotonicClock = MonotonicClock.create(testClock); assertThat(monotonicClock.nanoTime()).isEqualTo(testClock.nanoTime()); testClock.advanceNanos(12345); assertThat(monotonicClock.nanoTime()).isEqualTo(testClock.nanoTime()); }