public void Undo(int x, int y)
{
var position = new Vector(x, y);
var oldTile = new Tile {
WallId = 1
};
var change = new TileUpdate(position, oldTile, new Tile());
var extent = Mock.Of <Extent>(e => e.SetTile(position, It.IsAny <Tile>()));
Assert.That(change.Undo(extent));
Mock.Get(extent).Verify(e => e.SetTile(position, oldTile), Times.Once);
}
