3.1 PaletteFactory

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/FrameProcessor.Tests/PaletteFactoryTests.cs

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+using FrameProcessor.Domain;
+using FrameProcessor.ImagePipeline;
+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace FrameProcessor.Tests;
+
+public class PaletteFactoryTests
+{
+    private static readonly IReadOnlyList<PaletteEntry> Spectra6 = new[]
+    {
+        new PaletteEntry("black",  Color.FromPixel(new Rgba32(0x1F, 0x22, 0x26, 0xFF)), Color.FromPixel(new Rgba32(0x00, 0x00, 0x00, 0xFF))),
+        new PaletteEntry("white",  Color.FromPixel(new Rgba32(0xB9, 0xC7, 0xC9, 0xFF)), Color.FromPixel(new Rgba32(0xFF, 0xFF, 0xFF, 0xFF))),
+        new PaletteEntry("blue",   Color.FromPixel(new Rgba32(0x23, 0x3F, 0x8E, 0xFF)), Color.FromPixel(new Rgba32(0x00, 0x00, 0xFF, 0xFF))),
+        new PaletteEntry("green",  Color.FromPixel(new Rgba32(0x35, 0x56, 0x3A, 0xFF)), Color.FromPixel(new Rgba32(0x00, 0xFF, 0x00, 0xFF))),
+        new PaletteEntry("red",    Color.FromPixel(new Rgba32(0x62, 0x20, 0x1E, 0xFF)), Color.FromPixel(new Rgba32(0xFF, 0x00, 0x00, 0xFF))),
+        new PaletteEntry("yellow", Color.FromPixel(new Rgba32(0xC1, 0xBB, 0x1E, 0xFF)), Color.FromPixel(new Rgba32(0xFF, 0xFF, 0x00, 0xFF))),
+    };
+
+    [Fact]
+    public void BuildDisplay_PreservesOrderAndCount()
+    {
+        var palette = PaletteFactory.BuildDisplay(Spectra6).ToArray();
+
+        Assert.Equal(Spectra6.Count, palette.Length);
+        for (var i = 0; i < Spectra6.Count; i++)
+        {
+            Assert.Equal(Spectra6[i].DisplayColor, palette[i]);
+        }
+    }
+
+    [Fact]
+    public void BuildDevice_PreservesOrderAndCount()
+    {
+        var palette = PaletteFactory.BuildDevice(Spectra6).ToArray();
+
+        Assert.Equal(Spectra6.Count, palette.Length);
+        for (var i = 0; i < Spectra6.Count; i++)
+        {
+            Assert.Equal(Spectra6[i].DeviceColor, palette[i]);
+        }
+    }
+
+    [Fact]
+    public void BuildDisplay_AndBuildDevice_DiffWhenColorsDiffer()
+    {
+        var display = PaletteFactory.BuildDisplay(Spectra6).ToArray();
+        var device = PaletteFactory.BuildDevice(Spectra6).ToArray();
+
+        Assert.NotEqual(display, device);
+    }
+
+    [Fact]
+    public void Build_OnEmptyList_ReturnsEmptyPalette()
+    {
+        Assert.Equal(0, PaletteFactory.BuildDisplay(Array.Empty<PaletteEntry>()).Length);
+        Assert.Equal(0, PaletteFactory.BuildDevice(Array.Empty<PaletteEntry>()).Length);
+    }
+
+    [Fact]
+    public void Build_NullEntries_Throws()
+    {
+        Assert.Throws<ArgumentNullException>(() => PaletteFactory.BuildDisplay(null!));
+        Assert.Throws<ArgumentNullException>(() => PaletteFactory.BuildDevice(null!));
+    }
+}