public void FloorPlan_detects_adjacent_tiles()
        {
            FloorPlan plan = NSubstitute.Substitute.For <FloorPlan>();

            plan.FloorTiles.AddRange(_FillArea(5, 5));
            var center = plan.GetFloorTile(2, 2);

            plan.GetNorth(center).Should().BeSameAs(plan.GetFloorTile(2, 1));
            plan.GetSouth(center).Should().BeSameAs(plan.GetFloorTile(2, 3));
            plan.GetWest(center).Should().BeSameAs(plan.GetFloorTile(1, 2));
            plan.GetEast(center).Should().BeSameAs(plan.GetFloorTile(3, 2));

            plan.GetNorth(center).Should().NotBeSameAs(plan.GetFloorTile(2, 3));

            var corner = plan.GetFloorTile(0, 0);

            plan.GetNorth(corner).Should().BeNull();
            plan.GetSouth(corner).Should().BeSameAs(plan.GetFloorTile(0, 1));
            plan.GetWest(corner).Should().BeNull();
            plan.GetEast(corner).Should().BeSameAs(plan.GetFloorTile(1, 0));

            corner = plan.GetFloorTile(4, 4);
            plan.GetNorth(corner).Should().BeSameAs(plan.GetFloorTile(4, 3));
            plan.GetSouth(corner).Should().BeNull();
            plan.GetWest(corner).Should().BeSameAs(plan.GetFloorTile(3, 4));
            plan.GetEast(corner).Should().BeNull();
        }