Use error codes in test attributes.

Author: JimBobSquarePants

tests/ImageSharp.Drawing.Tests/TestUtilities/Attributes/WebGPUFactAttribute.cs

@@ -14,21 +14,7 @@ public WebGPUFactAttribute()
     {
         if (!WebGPUProbe.IsComputeSupported)
         {
-            this.Skip = "WebGPU compute is not available on this system.";
-        }
-    }
-}
-
-/// <summary>
-/// A <see cref="TheoryAttribute"/> that skips when WebGPU compute is not available on the current system.
-/// </summary>
-public class WebGPUTheoryAttribute : TheoryAttribute
-{
-    public WebGPUTheoryAttribute()
-    {
-        if (!WebGPUProbe.IsComputeSupported)
-        {
-            this.Skip = "WebGPU compute is not available on this system.";
+            this.Skip = WebGPUProbe.ComputeUnsupportedSkipMessage;
         }
     }
 }
@@ -38,8 +24,23 @@ public WebGPUTheoryAttribute()
 /// </summary>
 internal static class WebGPUProbe
 {
-    private static bool? computeSupported;
+    private static WebGPUEnvironmentError? computeProbeResult;
+
+    /// <summary>
+    /// Gets the cached WebGPU compute-pipeline probe result.
+    /// </summary>
+    internal static WebGPUEnvironmentError ComputeProbeResult
+        => computeProbeResult ??= WebGPUEnvironment.ProbeComputePipelineSupport();
 
+    /// <summary>
+    /// Gets a value indicating whether WebGPU compute is supported on the current system.
+    /// </summary>
     internal static bool IsComputeSupported
-        => computeSupported ??= WebGPUEnvironment.ProbeComputePipelineSupport() == WebGPUEnvironmentError.Success;
+        => ComputeProbeResult == WebGPUEnvironmentError.Success;
+
+    /// <summary>
+    /// Gets the skip message used when WebGPU compute is unavailable.
+    /// </summary>
+    internal static string ComputeUnsupportedSkipMessage
+        => $"WebGPU compute is not available on this system: {ComputeProbeResult}.";
 }

tests/ImageSharp.Drawing.Tests/TestUtilities/Attributes/WebGPUTheoryAttribute.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Drawing.Tests.TestUtilities.Attributes;
+
+/// <summary>
+/// A <see cref="TheoryAttribute"/> that skips when WebGPU compute is not available on the current system.
+/// </summary>
+public class WebGPUTheoryAttribute : TheoryAttribute
+{
+    public WebGPUTheoryAttribute()
+    {
+        if (!WebGPUProbe.IsComputeSupported)
+        {
+            this.Skip = WebGPUProbe.ComputeUnsupportedSkipMessage;
+        }
+    }
+}