Root inherited MemberData statics against the trimmer on maccatalyst CoreCLR

On maccatalyst-arm64 AllSubsets_CoreCLR (runtime-extra-platforms), ILLink strips
the inherited ConnectedStreamConformanceTests.ReadWrite_Success_MemberData and
CopyToAsync_AllDataCopied_MemberData statics, so xUnit's [MemberData] discovery
throws ArgumentException ("Could not find public static member ...") before the
test body runs, on CryptoStreamTests.ReadWrite_Success and
NetworkStreamTest.CopyToAsync_AllDataCopied.

Override each test to add a [DynamicDependency] root keeping the base statics
alive under trimming. xUnit does not inherit attributes from overridden virtual
methods, so the overrides also restate the base gating: the
IsMultithreadingSupported ConditionalTheory (System.Net.Sockets.Tests runs on
single-threaded wasi in CI) and the LinuxBionic and iOS/tvOS platform skips.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: kotlarmilos

src/libraries/System.Net.Sockets/tests/FunctionalTests/NetworkStreamTest.cs

@@ -45,10 +45,11 @@ public void Ctor_NullSocket_ThrowsArgumentNullExceptions()
             AssertExtensions.Throws<ArgumentNullException>("socket", () => new NetworkStream(null, FileAccess.ReadWrite, false));
         }
 
-        [Theory]
+        [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsMultithreadingSupported))]
         [MemberData(nameof(ConnectedStreamConformanceTests.CopyToAsync_AllDataCopied_MemberData), MemberType = typeof(ConnectedStreamConformanceTests))]
         [DynamicDependency(nameof(ConnectedStreamConformanceTests.CopyToAsync_AllDataCopied_MemberData), typeof(ConnectedStreamConformanceTests))]
-        [SkipOnPlatform(TestPlatforms.Android | TestPlatforms.iOS | TestPlatforms.tvOS, "Mobile platforms block binding to UNIX sockets")]
+        [SkipOnPlatform(TestPlatforms.LinuxBionic, "SElinux blocks UNIX sockets in our CI environment")]
+        [SkipOnPlatform(TestPlatforms.iOS | TestPlatforms.tvOS, "iOS/tvOS blocks binding to UNIX sockets")]
         public override Task CopyToAsync_AllDataCopied(int byteCount, bool useAsync) =>
             base.CopyToAsync_AllDataCopied(byteCount, useAsync);
 

src/libraries/System.Security.Cryptography/tests/CryptoStream.cs

@@ -39,7 +39,8 @@ protected override Task<StreamPair> CreateWrappedConnectedStreamsAsync(StreamPai
         [Theory]
         [MemberData(nameof(ConnectedStreamConformanceTests.ReadWrite_Success_MemberData), MemberType = typeof(ConnectedStreamConformanceTests))]
         [DynamicDependency(nameof(ConnectedStreamConformanceTests.ReadWrite_Success_MemberData), typeof(ConnectedStreamConformanceTests))]
-        [SkipOnPlatform(TestPlatforms.Android | TestPlatforms.iOS | TestPlatforms.tvOS, "Mobile platforms block binding to UNIX sockets")]
+        [SkipOnPlatform(TestPlatforms.LinuxBionic, "SElinux blocks UNIX sockets in our CI environment")]
+        [SkipOnPlatform(TestPlatforms.iOS | TestPlatforms.tvOS, "iOS/tvOS blocks binding to UNIX sockets")]
         public override Task ReadWrite_Success(ReadWriteMode mode, int writeSize, bool startWithFlush) => base.ReadWrite_Success(mode, writeSize, startWithFlush);
 
         [Fact]