### Question:
EventGroup { public void addEvents(Event... events) { for (Event e : events) { if (e != null) { this.events.add(e); } } } EventGroup();  EventGroup(List<Event> events);  EventGroup(Set<Event> events);  EventGroup(Event... events); Set<Event> getEvents(); void addEvents(Event... events); void clearEvents(); Event getMainEvent(); @Override String toString();  }### Answer:
@Test public void testAddEvents() { assertTrue(this.g.getEvents().isEmpty()); assertTrue(this.g.getEvents().isEmpty()); this.g.addEvents(this.event1); assertFalse(this.g.getEvents().isEmpty()); assertEquals(1, this.g.getEvents().size()); this.g.addEvents(this.event1); assertEquals(1, this.g.getEvents().size()); this.g.addEvents(this.event2, this.event2, this.event2); assertEquals(2, this.g.getEvents().size()); this.g.addEvents(this.event1, this.event2); assertEquals(2, this.g.getEvents().size()); this.g.addEvents(this.event1, this.event2, this.event3); assertEquals(3, this.g.getEvents().size()); this.g.clearEvents(); assertEquals(0, this.g.getEvents().size()); assertTrue(this.g.getEvents().isEmpty()); this.g.addEvents(this.event1, this.event2, this.event3); assertEquals(3, this.g.getEvents().size()); }