@Test(expected = IllegalArgumentException.class)
  public void deleteRoomNullId() {

    Room room = newRoom(RoomType.bungalow, 4);
    manager.createRoom(room);
    Long roomId = room.getId();
    room = manager.getRoom(roomId);
    room.setId(null);
    manager.deleteRoom(room);
  }
  @Test
  public void deleteRoom() {

    Room g1 = newRoom(RoomType.bungalow, 4);
    Room g2 = newRoom(RoomType.apartment, 2);
    manager.createRoom(g1);
    manager.createRoom(g2);

    assertNotNull(manager.getRoom(g1.getId()));
    assertNotNull(manager.getRoom(g2.getId()));

    manager.deleteRoom(g1);

    assertNull(manager.getRoom(g1.getId()));
    assertNotNull(manager.getRoom(g2.getId()));
  }
  @Test(expected = IllegalArgumentException.class)
  public void deleteRoomNull() {

    manager.deleteRoom(null);
  }