diff --git a/src/libraries/Common/tests/TestUtilities/System/IO/FileCleanupTestBase.cs b/src/libraries/Common/tests/TestUtilities/System/IO/FileCleanupTestBase.cs
index a0542ef930c028..02ffa607c94aa7 100644
--- a/src/libraries/Common/tests/TestUtilities/System/IO/FileCleanupTestBase.cs
+++ b/src/libraries/Common/tests/TestUtilities/System/IO/FileCleanupTestBase.cs
@@ -79,7 +79,7 @@ protected virtual void Dispose(bool disposing)
/// An optional index value to use as a suffix on the file name. Typically a loop index.
/// The member name of the function calling this method.
/// The line number of the function calling this method.
- protected string GetTestFilePath(int? index = null, [CallerMemberName] string memberName = null, [CallerLineNumber] int lineNumber = 0) =>
+ protected virtual string GetTestFilePath(int? index = null, [CallerMemberName] string memberName = null, [CallerLineNumber] int lineNumber = 0) =>
Path.Combine(TestDirectory, GetTestFileName(index, memberName, lineNumber));
/// Gets a test file name that is associated with the call site.
diff --git a/src/libraries/System.IO.FileSystem/tests/FileStream/FileStreamConformanceTests.Windows.cs b/src/libraries/System.IO.FileSystem/tests/FileStream/FileStreamConformanceTests.Windows.cs
new file mode 100644
index 00000000000000..1cfbd351824de8
--- /dev/null
+++ b/src/libraries/System.IO.FileSystem/tests/FileStream/FileStreamConformanceTests.Windows.cs
@@ -0,0 +1,179 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.Win32.SafeHandles;
+using System.ComponentModel;
+using System.IO.Pipes;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using System.Text;
+using System.ServiceProcess;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace System.IO.Tests
+{
+ [PlatformSpecific(TestPlatforms.Windows)] // DOS device paths (\\.\ and \\?\) are a Windows concept
+ public class UnseekableDeviceFileStreamConnectedConformanceTests : ConnectedStreamConformanceTests
+ {
+ protected override async Task CreateConnectedStreamsAsync()
+ {
+ string pipeName = FileSystemTest.GetNamedPipeServerStreamName();
+ string pipePath = Path.GetFullPath($@"\\.\pipe\{pipeName}");
+
+ var server = new NamedPipeServerStream(pipeName, PipeDirection.In);
+ var clienStream = new FileStream(File.OpenHandle(pipePath, FileMode.Open, FileAccess.Write, FileShare.None), FileAccess.Write);
+
+ await server.WaitForConnectionAsync();
+
+ var serverStrean = new FileStream(new SafeFileHandle(server.SafePipeHandle.DangerousGetHandle(), true), FileAccess.Read);
+
+ server.SafePipeHandle.SetHandleAsInvalid();
+
+ return (serverStrean, clienStream);
+ }
+
+ protected override Type UnsupportedConcurrentExceptionType => null;
+ protected override bool UsableAfterCanceledReads => false;
+ protected override bool FullyCancelableOperations => false;
+ protected override bool BlocksOnZeroByteReads => OperatingSystem.IsWindows();
+ protected override bool SupportsConcurrentBidirectionalUse => false;
+ }
+
+ [PlatformSpecific(TestPlatforms.Windows)] // DOS device paths (\\.\ and \\?\) are a Windows concept
+ public class SeekableDeviceFileStreamStandaloneConformanceTests : UnbufferedAsyncFileStreamStandaloneConformanceTests
+ {
+ protected override string GetTestFilePath(int? index = null, [CallerMemberName] string memberName = null, [CallerLineNumber] int lineNumber = 0)
+ {
+ string filePath = Path.GetFullPath(base.GetTestFilePath(index, memberName, lineNumber));
+ string drive = Path.GetPathRoot(filePath);
+ StringBuilder volumeNameBuffer = new StringBuilder(filePath.Length + 1024);
+
+ // the following method maps drive letter like "C:\" to a DeviceID (a DOS device path)
+ // example: "\\?\Volume{724edb31-eaa5-4728-a4e3-f2474fd34ae2}\"
+ if (!GetVolumeNameForVolumeMountPoint(drive, volumeNameBuffer, volumeNameBuffer.Capacity))
+ {
+ throw new Win32Exception(Marshal.GetLastPInvokeError(), "GetVolumeNameForVolumeMountPoint failed");
+ }
+
+ // instead of:
+ // 'C:\Users\x\AppData\Local\Temp\y\z
+ // we want something like:
+ // '\\.\Volume{724edb31-eaa5-4728-a4e3-f2474fd34ae2}\Users\x\AppData\Local\Temp\y\z
+ string devicePath = filePath.Replace(drive, volumeNameBuffer.ToString());
+ Assert.StartsWith(@"\\?\", devicePath);
+#if DEBUG
+ // we do want to test \\.\ prefix as well
+ devicePath = devicePath.Replace(@"\\?\", @"\\.\");
+#endif
+
+ return devicePath;
+ }
+
+ [DllImport(Interop.Libraries.Kernel32, EntryPoint = "GetVolumeNameForVolumeMountPointW", CharSet = CharSet.Unicode, BestFitMapping = false, SetLastError = true)]
+ private static extern bool GetVolumeNameForVolumeMountPoint(string volumeName, StringBuilder uniqueVolumeName, int uniqueNameBufferCapacity);
+ }
+
+ [PlatformSpecific(TestPlatforms.Windows)] // the test setup is Windows-specifc
+ [Collection("NoParallelTests")] // don't run in parallel, as file sharing logic is not thread-safe
+ [OuterLoop("Requires admin privileges to create a file share")]
+ [ConditionalClass(typeof(UncFilePathFileStreamStandaloneConformanceTests), nameof(CanShareFiles))]
+ public class UncFilePathFileStreamStandaloneConformanceTests : UnbufferedAsyncFileStreamStandaloneConformanceTests
+ {
+ public static bool CanShareFiles => _canShareFiles.Value;
+
+ private static Lazy _canShareFiles = new Lazy(() =>
+ {
+ if (!PlatformDetection.IsWindowsAndElevated || PlatformDetection.IsWindowsNanoServer)
+ {
+ return false;
+ }
+
+ // the "Server Service" allows for file sharing. It can be disabled on some of our CI machines.
+ using (ServiceController sharingService = new ServiceController("Server"))
+ {
+ return sharingService.Status == ServiceControllerStatus.Running;
+ }
+ });
+
+ protected override string GetTestFilePath(int? index = null, [CallerMemberName] string memberName = null, [CallerLineNumber] int lineNumber = 0)
+ {
+ string testDirectoryPath = Path.GetFullPath(TestDirectory);
+ string shareName = new DirectoryInfo(testDirectoryPath).Name;
+ string fileName = GetTestFileName(index, memberName, lineNumber);
+
+ SHARE_INFO_502 shareInfo = default;
+ shareInfo.shi502_netname = shareName;
+ shareInfo.shi502_path = testDirectoryPath;
+ shareInfo.shi502_remark = "folder created to test UNC file paths";
+ shareInfo.shi502_max_uses = -1;
+
+ int infoSize = Marshal.SizeOf(shareInfo);
+ IntPtr infoBuffer = Marshal.AllocCoTaskMem(infoSize);
+
+ try
+ {
+ Marshal.StructureToPtr(shareInfo, infoBuffer, false);
+
+ int shareResult = NetShareAdd(string.Empty, 502, infoBuffer, IntPtr.Zero);
+
+ if (shareResult != 0 && shareResult != 2118) // is a failure that is not a NERR_DuplicateShare
+ {
+ throw new Exception($"Failed to create a file share, NetShareAdd returned {shareResult}");
+ }
+ }
+ finally
+ {
+ Marshal.FreeCoTaskMem(infoBuffer);
+ }
+
+ // now once the folder has been shared we can use "localhost" to access it:
+ // both type of slashes are valid, so let's test one for Debug and another for other configs
+#if DEBUG
+ return @$"//localhost/{shareName}/{fileName}";
+#else
+ return @$"\\localhost\{shareName}\{fileName}";
+#endif
+ }
+
+ protected override void Dispose(bool disposing)
+ {
+ string testDirectoryPath = Path.GetFullPath(TestDirectory);
+ string shareName = new DirectoryInfo(testDirectoryPath).Name;
+
+ try
+ {
+ NetShareDel(string.Empty, shareName, 0);
+ }
+ finally
+ {
+ base.Dispose(disposing);
+ }
+ }
+
+ [StructLayout(LayoutKind.Sequential)]
+ public struct SHARE_INFO_502
+ {
+ [MarshalAs(UnmanagedType.LPWStr)]
+ public string shi502_netname;
+ public uint shi502_type;
+ [MarshalAs(UnmanagedType.LPWStr)]
+ public string shi502_remark;
+ public int shi502_permissions;
+ public int shi502_max_uses;
+ public int shi502_current_uses;
+ [MarshalAs(UnmanagedType.LPWStr)]
+ public string shi502_path;
+ public IntPtr shi502_passwd;
+ public int shi502_reserved;
+ public IntPtr shi502_security_descriptor;
+ }
+
+ [DllImport(Interop.Libraries.Netapi32)]
+ public static extern int NetShareAdd([MarshalAs(UnmanagedType.LPWStr)]string servername, int level, IntPtr buf, IntPtr parm_err);
+
+ [DllImport(Interop.Libraries.Netapi32)]
+ public static extern int NetShareDel([MarshalAs(UnmanagedType.LPWStr)] string servername, [MarshalAs(UnmanagedType.LPWStr)] string netname, int reserved);
+ }
+}
diff --git a/src/libraries/System.IO.FileSystem/tests/Net5CompatTests/System.IO.FileSystem.Net5Compat.Tests.csproj b/src/libraries/System.IO.FileSystem/tests/Net5CompatTests/System.IO.FileSystem.Net5Compat.Tests.csproj
index 58669657e51b14..04d57626857104 100644
--- a/src/libraries/System.IO.FileSystem/tests/Net5CompatTests/System.IO.FileSystem.Net5Compat.Tests.csproj
+++ b/src/libraries/System.IO.FileSystem/tests/Net5CompatTests/System.IO.FileSystem.Net5Compat.Tests.csproj
@@ -25,6 +25,7 @@
+
diff --git a/src/libraries/System.IO.FileSystem/tests/System.IO.FileSystem.Tests.csproj b/src/libraries/System.IO.FileSystem/tests/System.IO.FileSystem.Tests.csproj
index 94cec86ce3a9aa..bf845ce77b57f2 100644
--- a/src/libraries/System.IO.FileSystem/tests/System.IO.FileSystem.Tests.csproj
+++ b/src/libraries/System.IO.FileSystem/tests/System.IO.FileSystem.Tests.csproj
@@ -72,6 +72,7 @@
+
@@ -80,6 +81,7 @@
+