Add tests for grid

LibGame.Tests/Collections/GridTests.cs

@@ -0,0 +1,44 @@
+using LibGame.Collections;
+using LibGame.Mathematics;
+
+namespace LibGame.Tests.Collections;
+public static class GridTests
+{
+    private readonly record struct CR(int Column, int Row);
+
+    [Fact(DisplayName = "Smoke test for `Grid<T>`")]
+    public static void SmokeTest()
+    {
+        var values = new CR[]
+        {
+            new CR(0, 0), new CR(1, 0), new CR(2, 0),
+            new CR(0, 1), new CR(1, 1), new CR(2, 1),
+            new CR(0, 2), new CR(1, 2), new CR(2, 2),
+            new CR(0, 3), new CR(1, 3), new CR(2, 3),
+        };
+
+        var grid = new Grid<CR>(values, 3, 4);
+
+        Equal(3, grid.Columns);
+        Equal(4, grid.Rows);
+        Equal(12, grid.Count);
+
+        for (var i = 0; i < 12; i++)
+        {
+            var (c, r) = Indexes.ToTwoDimensional(i, 3);
+            var value = new CR(c, r);
+            Equal(grid[i], value);
+            Equal(grid[c, r], value);
+        }
+
+        var slice = grid.Slice(2, 1, 2, 1);
+        Equal(1, slice.Columns);
+        Equal(1, slice.Rows);
+
+        Equal(new CR(2, 2), slice[0]);
+
+        var safeSlice = grid.SliceAtMost(2, 10, 2, 10);
+        Equal(1, safeSlice.Columns);
+        Equal(2, safeSlice.Rows);
+    }
+}

LibGame/Collections/Grid.cs

@@ -72,6 +72,8 @@ internal ReadOnlyGridSlice(T[] tiles, int stride, int columnOffset, int columnSp
         Debug.Assert(rowOffset >= 0);
         Debug.Assert(rowSpan > 0);
 
+
+
         this.tiles = tiles;
         this.stride = stride;
 
@@ -172,6 +174,16 @@ public IReadOnlyGrid<T> AsReadOnly()
 
     public IReadOnlyGrid<T> Slice(int columnOffset, int columnSpan, int rowOffset, int rowSpan)
     {
+        if (columnOffset + columnSpan > this.Columns)
+        {
+            throw new ArgumentOutOfRangeException(nameof(columnSpan));
+        }
+
+        if (rowOffset + rowSpan > this.Rows)
+        {
+            throw new ArgumentOutOfRangeException(nameof(rowSpan));
+        }
+
         return new ReadOnlyGridSlice<T>(this.Tiles, this.Columns, columnOffset, columnSpan, rowOffset, rowSpan);
     }
 }

LibGame/Tiles/TileUtilities.cs

@@ -1,5 +1,4 @@
 using System.Numerics;
-using LibGame.Mathematics;
 
 namespace LibGame.Tiles;
 
@@ -40,39 +39,6 @@ public static TileSide GetOppositeSide(TileSide side)
         };
     }
 
-    public static Neighbours<T> GetNeighboursFromGrid<T>(T[] grid, int columns, int rows, int index, T fallback)
-        where T : struct
-    {
-        var nw = GetFromGrid(grid, columns, rows, index, -1, -1, fallback);
-        var n = GetFromGrid(grid, columns, rows, index, 0, -1, fallback);
-        var ne = GetFromGrid(grid, columns, rows, index, 1, -1, fallback);
-        var w = GetFromGrid(grid, columns, rows, index, -1, 0, fallback);
-        var e = GetFromGrid(grid, columns, rows, index, 1, 0, fallback);
-        var sw = GetFromGrid(grid, columns, rows, index, -1, 1, fallback);
-        var s = GetFromGrid(grid, columns, rows, index, 0, 1, fallback);
-        var se = GetFromGrid(grid, columns, rows, index, 1, 1, fallback);
-
-        return new Neighbours<T>(nw, n, ne, w, e, sw, s, se);
-    }
-
-
-    public static T GetFromGrid<T>(T[] grid, int columns, int rows, int index, int offsetColumn, int offsetRow, T fallBack)
-    {
-        var (c, r) = Indexes.ToTwoDimensional(index, columns);
-        c += offsetColumn;
-        r += offsetRow;
-
-        if (c >= 0 && c < columns && r >= 0 && r < rows)
-        {
-            var i = Indexes.ToOneDimensional(c, r, columns);
-            return grid[i];
-        }
-
-        return fallBack;
-    }
-
-
-
     public static Vector3 GetCornerPosition(int column, int row, Tile tile, TileCorner c)
     {
         var offset = tile.GetHeight(c);