From 229598725742a6508b5248d292103b09cd202d43 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Luthi?= <cedric.luthi@gmail.com>
Date: Fri, 29 Nov 2024 11:32:32 +0100
Subject: [PATCH] Add support for the [UnsupportedOSPlatform] attribute

---
 .../Sdk/TestMethodExtensions.cs               | 45 ++++++++++++++++---
 test/Xunit.SkippableFact.Tests/SampleTests.cs |  8 ++++
 2 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/src/Xunit.SkippableFact/Sdk/TestMethodExtensions.cs b/src/Xunit.SkippableFact/Sdk/TestMethodExtensions.cs
index 2f316b6..1bb3fcd 100644
--- a/src/Xunit.SkippableFact/Sdk/TestMethodExtensions.cs
+++ b/src/Xunit.SkippableFact/Sdk/TestMethodExtensions.cs
@@ -21,16 +21,20 @@ internal static class TestMethodExtensions
 #if NET462
         return null;
 #else
-        var platforms = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
-        AddPlatforms(platforms, testMethod.Method.GetCustomAttributes("System.Runtime.Versioning.SupportedOSPlatformAttribute"));
-        AddPlatforms(platforms, testMethod.Method.Type.GetCustomAttributes("System.Runtime.Versioning.SupportedOSPlatformAttribute"));
+        HashSet<string> unsupportedPlatforms = GetPlatforms(testMethod, "UnsupportedOSPlatform");
+        string? unsupportedPlatform = unsupportedPlatforms.FirstOrDefault(MatchesCurrentPlatform);
+        if (unsupportedPlatform is not null)
+        {
+            return $"Unsupported on {unsupportedPlatform}";
+        }
 
-        if (platforms.Count == 0 || platforms.Any(MatchesCurrentPlatform))
+        HashSet<string> supportedPlatforms = GetPlatforms(testMethod, "SupportedOSPlatform");
+        if (supportedPlatforms.Count == 0 || supportedPlatforms.Any(MatchesCurrentPlatform))
         {
             return null;
         }
 
-        string platformsDescription = platforms.Count == 1 ? platforms.First() : string.Join(", ", platforms.Reverse().Skip(1).Reverse()) + " and " + platforms.Last();
+        string platformsDescription = supportedPlatforms.Count == 1 ? supportedPlatforms.First() : string.Join(", ", supportedPlatforms.Reverse().Skip(1).Reverse()) + " and " + supportedPlatforms.Last();
         return $"Only supported on {platformsDescription}";
 #endif
     }
@@ -83,6 +87,37 @@ private static bool MatchesCurrentVersion(int major, int minor, int build, int r
         return currentRevision >= revision;
     }
 
+    /// <summary>
+    /// Returns the collection of platforms defined by the specified <paramref name="platformAttributeName"/> that decorate the test method and the test class.
+    /// </summary>
+    /// <param name="testMethod">The <see cref="ITestMethod"/>.</param>
+    /// <param name="platformAttributeName">Either <c>SupportedOSPlatform</c> or <c>UnsupportedOSPlatform</c>.</param>
+    /// <example>
+    /// <para>
+    /// Calling GetPlatforms(testMethod, "SupportedOSPlatform") where <paramref name="testMethod"/> represents <c>MyTest</c> returns ["Linux", "macOS"].
+    /// </para>
+    /// <code>
+    /// [SupportedOSPlatform("macOS")]
+    /// public class MyTests
+    /// {
+    ///     [SkippableFact]
+    ///     [SupportedOSPlatform("Linux")]
+    ///     public void MyTest()
+    ///     {
+    ///     }
+    /// }
+    /// </code>
+    /// </example>
+    /// <returns>The collection of platforms defined by the specified <paramref name="platformAttributeName"/> that decorate the test method and the test class.</returns>
+    private static HashSet<string> GetPlatforms(ITestMethod testMethod, string platformAttributeName)
+    {
+        string platformAttribute = $"System.Runtime.Versioning.{platformAttributeName}Attribute";
+        var platforms = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+        AddPlatforms(platforms, testMethod.Method.GetCustomAttributes(platformAttribute));
+        AddPlatforms(platforms, testMethod.Method.Type.GetCustomAttributes(platformAttribute));
+        return platforms;
+    }
+
     private static void AddPlatforms(HashSet<string> platforms, IEnumerable<IAttributeInfo> supportedPlatformAttributes)
     {
         foreach (IAttributeInfo supportedPlatformAttribute in supportedPlatformAttributes)
diff --git a/test/Xunit.SkippableFact.Tests/SampleTests.cs b/test/Xunit.SkippableFact.Tests/SampleTests.cs
index 9bd28f8..8b91925 100644
--- a/test/Xunit.SkippableFact.Tests/SampleTests.cs
+++ b/test/Xunit.SkippableFact.Tests/SampleTests.cs
@@ -140,5 +140,13 @@ public void AndroidAndBrowserAndWasiOnly()
     {
         Assert.True(OperatingSystem.IsAndroid() || OperatingSystem.IsBrowser() || OperatingSystem.IsWasi(), "This should only run on Android, Browser and Wasi");
     }
+
+    [SkippableFact, UnsupportedOSPlatform("Linux"), UnsupportedOSPlatform("macOS"), UnsupportedOSPlatform("Windows")]
+    public void UnsupportedPlatforms()
+    {
+        Assert.False(OperatingSystem.IsLinux());
+        Assert.False(OperatingSystem.IsMacOS());
+        Assert.False(OperatingSystem.IsWindows());
+    }
 #endif
 }