### Question:
DefaultExecutor implements Executor { @Override public void orFallBackTo(Runnable defaultClosure) { defaultClosure.run(); }  @Override Executor perform(Closure closure); @Override void orFallBackTo(Runnable defaultClosure);  }### Answer:
@Test public void performsDefaultAction() throws Exception { Runnable action = mock(Runnable.class); new DefaultExecutor().orFallBackTo(action); verify(action).run(); }