feat.融合桌面组件展示优化

LanMountainDesktop.Tests/FusedDesktopLibraryPreviewLayoutTests.cs

@@ -0,0 +1,66 @@
+using LanMountainDesktop.Views;
+using Xunit;
+
+namespace LanMountainDesktop.Tests;
+
+public sealed class FusedDesktopLibraryPreviewLayoutTests
+{
+    [Fact]
+    public void Calculate_PreservesLandscapeComponentRatio()
+    {
+        var metrics = FusedDesktopLibraryPreviewLayout.Calculate(
+            widthCells: 4,
+            heightCells: 2,
+            stageWidth: 520,
+            stageHeight: 320);
+
+        Assert.Equal(4, metrics.WidthCells);
+        Assert.Equal(2, metrics.HeightCells);
+        Assert.True(metrics.Width > metrics.Height);
+        Assert.Equal(2d, metrics.Width / metrics.Height, precision: 3);
+    }
+
+    [Fact]
+    public void Calculate_PreservesPortraitComponentRatio()
+    {
+        var metrics = FusedDesktopLibraryPreviewLayout.Calculate(
+            widthCells: 2,
+            heightCells: 4,
+            stageWidth: 520,
+            stageHeight: 320);
+
+        Assert.Equal(2, metrics.WidthCells);
+        Assert.Equal(4, metrics.HeightCells);
+        Assert.True(metrics.Height > metrics.Width);
+        Assert.Equal(0.5d, metrics.Width / metrics.Height, precision: 3);
+    }
+
+    [Fact]
+    public void Calculate_FitsPreviewInsideStageInsets()
+    {
+        var metrics = FusedDesktopLibraryPreviewLayout.Calculate(
+            widthCells: 4,
+            heightCells: 4,
+            stageWidth: 420,
+            stageHeight: 260);
+
+        Assert.Equal(metrics.Width, metrics.Height, precision: 3);
+        Assert.True(metrics.Width <= 420);
+        Assert.True(metrics.Height <= 260);
+        Assert.True(metrics.CellSize > 0);
+    }
+
+    [Fact]
+    public void Calculate_UsesFallbackStageWhenBoundsAreNotMeasured()
+    {
+        var metrics = FusedDesktopLibraryPreviewLayout.Calculate(
+            widthCells: 4,
+            heightCells: 2,
+            stageWidth: 0,
+            stageHeight: 0);
+
+        Assert.True(metrics.Width > 0);
+        Assert.True(metrics.Height > 0);
+        Assert.Equal(2d, metrics.Width / metrics.Height, precision: 3);
+    }
+}