@Test
  public void togglingUnlitLightTurnsOn1Light() {
    int x = getRandomCoordinate();
    int y = getRandomCoordinate();

    grid.toggle(x, y);
    assertEquals(1, grid.getNumberOfLitLights());
  }
  @Test
  public void togglingLitLightTurnsOff1Light() {
    turnOnAllLights();
    int x = getRandomCoordinate();
    int y = getRandomCoordinate();

    grid.toggle(x, y);
    assertEquals(ROWS * COLUMNS - 1, grid.getNumberOfLitLights());
  }