### Question:
Stopwatch { public void start(String eventName) { startEvent(eventName); }  void start(String eventName); Event stop(String eventName); void lap(String eventName);  }### Answer:
@Test(expected = IllegalArgumentException.class) public void shouldThrowExceptionWhenTryingToStartAlreadyStartedEvent() { Stopwatch stopwatch = new Stopwatch(); stopwatch.start("e"); stopwatch.start("e"); }