public void TestMementoToReturnValidObjectState()
{
var grid = new Grid();
var tile = new Tile("1", 1, TileType.Number);
var emptyTile = new Tile(string.Empty, GlobalConstants.TotalTilesCount - 1, TileType.Empty);
var anotherTile = new Tile("2", 2, TileType.Number);
grid.AddTile(tile);
grid.AddTile(emptyTile);
Memento memento = grid.SaveMemento();
grid.AddTile(anotherTile);
grid.RestoreMemento(memento);
var actual = grid.TilesCount;
var expected = 2;
Assert.AreEqual(expected, actual);
}