finally

Minint.Tests/ImageEffectsTests.cs

@@ -0,0 +1,65 @@
+using Minint.Core.Models;
+using Minint.Core.Services.Impl;
+
+namespace Minint.Tests;
+
+public class ImageEffectsTests
+{
+    private readonly ImageEffectsService _effects = new();
+
+    [Fact]
+    public void ApplyGrayscale_ConvertsColors()
+    {
+        var doc = new MinintDocument("test");
+        var red = new RgbaColor(255, 0, 0, 255);
+        doc.EnsureColorCached(red);
+
+        _effects.ApplyGrayscale(doc);
+
+        var gray = doc.Palette[1];
+        Assert.Equal(gray.R, gray.G);
+        Assert.Equal(gray.G, gray.B);
+        Assert.Equal(255, gray.A);
+        // BT.601: 0.299*255 ≈ 76
+        Assert.InRange(gray.R, 74, 78);
+    }
+
+    [Fact]
+    public void ApplyGrayscale_PreservesTransparentIndex()
+    {
+        var doc = new MinintDocument("test");
+        doc.EnsureColorCached(new RgbaColor(100, 200, 50, 255));
+
+        _effects.ApplyGrayscale(doc);
+
+        Assert.Equal(RgbaColor.Transparent, doc.Palette[0]);
+    }
+
+    [Fact]
+    public void ApplyContrast_IncreasesContrast()
+    {
+        var doc = new MinintDocument("test");
+        var midGray = new RgbaColor(128, 128, 128, 255);
+        var lightGray = new RgbaColor(192, 192, 192, 255);
+        doc.EnsureColorCached(midGray);
+        doc.EnsureColorCached(lightGray);
+
+        _effects.ApplyContrast(doc, 2.0);
+
+        // midGray (128) stays ~128: factor*(128-128)+128 = 128
+        Assert.InRange(doc.Palette[1].R, 126, 130);
+        // lightGray (192): factor*(192-128)+128 = 2*64+128 = 256 → clamped to 255
+        Assert.Equal(255, doc.Palette[2].R);
+    }
+
+    [Fact]
+    public void ApplyContrast_PreservesAlpha()
+    {
+        var doc = new MinintDocument("test");
+        doc.EnsureColorCached(new RgbaColor(100, 100, 100, 200));
+
+        _effects.ApplyContrast(doc, 1.5);
+
+        Assert.Equal(200, doc.Palette[1].A);
+    }
+}