finally

Minint.Tests/FloodFillTests.cs

@@ -0,0 +1,52 @@
+using Minint.Core.Models;
+using Minint.Core.Services.Impl;
+
+namespace Minint.Tests;
+
+public class FloodFillTests
+{
+    private readonly FloodFillService _fill = new();
+
+    [Fact]
+    public void Fill_EmptyLayer_FillsAll()
+    {
+        var layer = new MinintLayer("L1", 9); // 3x3, all zeros
+        _fill.Fill(layer, 0, 0, 1, 3, 3);
+
+        Assert.All(layer.Pixels, px => Assert.Equal(1, px));
+    }
+
+    [Fact]
+    public void Fill_SameColor_NoOp()
+    {
+        var layer = new MinintLayer("L1", 4);
+        Array.Fill(layer.Pixels, 2);
+        _fill.Fill(layer, 0, 0, 2, 2, 2);
+
+        Assert.All(layer.Pixels, px => Assert.Equal(2, px));
+    }
+
+    [Fact]
+    public void Fill_Bounded_DoesNotCrossBorder()
+    {
+        // 3x3 grid with a wall:
+        // 0 0 0
+        // 1 1 1
+        // 0 0 0
+        var layer = new MinintLayer("L1", 9);
+        layer.Pixels[3] = 1; // (0,1)
+        layer.Pixels[4] = 1; // (1,1)
+        layer.Pixels[5] = 1; // (2,1)
+
+        _fill.Fill(layer, 0, 0, 2, 3, 3);
+
+        // Top row should be filled
+        Assert.Equal(2, layer.Pixels[0]);
+        Assert.Equal(2, layer.Pixels[1]);
+        Assert.Equal(2, layer.Pixels[2]);
+        // Wall untouched
+        Assert.Equal(1, layer.Pixels[3]);
+        // Bottom row untouched (blocked by wall)
+        Assert.Equal(0, layer.Pixels[6]);
+    }
+}