### Question:
IncrementingEnvironmentEdge implements EnvironmentEdge { @Override public synchronized long currentTimeMillis() { return timeIncrement++; }  @Override synchronized long currentTimeMillis();  }### Answer:
@Test public void testGetCurrentTimeUsesSystemClock() { IncrementingEnvironmentEdge edge = new IncrementingEnvironmentEdge(); assertEquals(1, edge.currentTimeMillis()); assertEquals(2, edge.currentTimeMillis()); assertEquals(3, edge.currentTimeMillis()); assertEquals(4, edge.currentTimeMillis()); }