Enable MacCatalyst tests in System.Runtime.Extensions.Tests (#51169)

We now have the necessary support in the runtime and arcade.

src/libraries/System.Runtime.Extensions/tests/System/OperatingSystemTests.cs

@@ -11,7 +11,7 @@ public static class OperatingSystemTests
         {
             "Android",
             "macOS",
-            //"MacCatalyst",
+            "MacCatalyst",
             "iOS",
             "tvOS",
             "watchOS",
@@ -124,13 +124,11 @@ public static void OSX_Is_Treated_as_macOS()
             AssertVersionChecks(true, (major, minor, build) => OperatingSystem.IsOSPlatformVersionAtLeast("osx", major, minor, build));
         }
 
-        /* Disable Mac Catalyst tests until Arcade and xharness are ready
         [Fact, PlatformSpecific(TestPlatforms.MacCatalyst)]
         public static void TestIsOSPlatform_MacCatalyst() => TestIsOSPlatform("MacCatalyst", OperatingSystem.IsMacCatalyst);
 
         [Fact, PlatformSpecific(TestPlatforms.MacCatalyst)]
         public static void TestIsOSVersionAtLeast_MacCatalyst() => TestIsOSVersionAtLeast("MacCatalyst");
-        */
 
         [Fact, PlatformSpecific(TestPlatforms.tvOS)]
         public static void TestIsOSPlatform_TvOS() => TestIsOSPlatform("tvOS", OperatingSystem.IsTvOS);
@@ -165,7 +163,7 @@ private static void TestIsOSPlatform(string currentOSName, Func<bool> currentOSC
                 OperatingSystem.IsAndroid(),
                 OperatingSystem.IsIOS(),
                 OperatingSystem.IsMacOS(),
-                //OperatingSystem.IsMacCatalyst(),
+                OperatingSystem.IsMacCatalyst(),
                 OperatingSystem.IsTvOS(),
                 OperatingSystem.IsWatchOS(),
                 OperatingSystem.IsWindows()
@@ -188,7 +186,7 @@ private static void TestIsOSVersionAtLeast(string currentOSName)
             AssertVersionChecks(currentOSName.Equals("Android", StringComparison.OrdinalIgnoreCase), OperatingSystem.IsAndroidVersionAtLeast);
             AssertVersionChecks(currentOSName.Equals("iOS", StringComparison.OrdinalIgnoreCase), OperatingSystem.IsIOSVersionAtLeast);
             AssertVersionChecks(currentOSName.Equals("macOS", StringComparison.OrdinalIgnoreCase), OperatingSystem.IsMacOSVersionAtLeast);
-            //AssertVersionChecks(currentOSName.Equals("MacCatalyst", StringComparison.OrdinalIgnoreCase), OperatingSystem.IsMacCatalystVersionAtLeast);
+            AssertVersionChecks(currentOSName.Equals("MacCatalyst", StringComparison.OrdinalIgnoreCase), OperatingSystem.IsMacCatalystVersionAtLeast);
             AssertVersionChecks(currentOSName.Equals("tvOS", StringComparison.OrdinalIgnoreCase), OperatingSystem.IsTvOSVersionAtLeast);
             AssertVersionChecks(currentOSName.Equals("watchOS", StringComparison.OrdinalIgnoreCase), OperatingSystem.IsWatchOSVersionAtLeast);
             AssertVersionChecks(currentOSName.Equals("Windows", StringComparison.OrdinalIgnoreCase), OperatingSystem.IsWindowsVersionAtLeast);