@Test
  public void testPlaceShip() throws ShipTooCloseException {
    Coordinate[] shipCoordinates = new Coordinate[] {new Coordinate(1, 1)};
    battlefield.placeShip(shipCoordinates);

    assertArrayEquals(new Boolean[] {true}, battlefield.getShipsByCoordinates(shipCoordinates));
  }
 @Test(expected = ShipTooCloseException.class)
 public void testExceptionWhenShipsTooClose() throws ShipTooCloseException {
   battlefield.placeShip(new Coordinate[] {new Coordinate(1, 1), new Coordinate(1, 2)});
   battlefield.placeShip(new Coordinate[] {new Coordinate(2, 1)});
 }