Add FileStreamFactory and support for mocking FileStreams

System.IO.Abstractions/FileStreamFactory.cs

@@ -0,0 +1,62 @@
+using System.Security.AccessControl;
+using Microsoft.Win32.SafeHandles;
+
+namespace System.IO.Abstractions
+{
+    [Serializable]
+    internal sealed class FileStreamFactory : IFileStreamFactory
+    {
+        public Stream Create(string path, FileMode mode)
+            => new FileStream(path, mode);
+
+        public Stream Create(string path, FileMode mode, FileAccess access)
+            => new FileStream(path, mode, access);
+
+        public Stream Create(string path, FileMode mode, FileAccess access, FileShare share)
+            => new FileStream(path, mode, access, share);
+
+        public Stream Create(string path, FileMode mode, FileAccess access, FileShare share, int bufferSize)
+            => new FileStream(path, mode, access, share, bufferSize);
+
+        public Stream Create(string path, FileMode mode, FileAccess access, FileShare share, int bufferSize, FileOptions options)
+            => new FileStream(path, mode, access, share, bufferSize, options);
+
+        public Stream Create(string path, FileMode mode, FileAccess access, FileShare share, int bufferSize, bool useAsync)
+            => new FileStream(path, mode, access, share, bufferSize, useAsync);
+
+        public Stream Create(SafeFileHandle handle, FileAccess access)
+            => new FileStream(handle, access);
+
+        public Stream Create(SafeFileHandle handle, FileAccess access, int bufferSize)
+            => new FileStream(handle, access, bufferSize);
+
+        public Stream Create(SafeFileHandle handle, FileAccess access, int bufferSize, bool isAsync)
+            => new FileStream(handle, access, bufferSize, isAsync);
+
+#if NET40
+        public Stream Create(string path, FileMode mode, FileSystemRights rights, FileShare share, int bufferSize, FileOptions options, FileSecurity fileSecurity)
+            => new FileStream(path, mode, rights, share, bufferSize, options, fileSecurity);
+
+        public Stream Create(string path, FileMode mode, FileSystemRights rights, FileShare share, int bufferSize, FileOptions options)
+            => new FileStream(path, mode, rights, share, bufferSize, options);
+#endif
+
+#if NET40 || NETSTANDARD_20
+        [Obsolete("This method has been deprecated. Please use new Create(SafeFileHandle handle, FileAccess access) instead. http://go.microsoft.com/fwlink/?linkid=14202")]
+        public Stream Create(IntPtr handle, FileAccess access)
+            => new FileStream(handle, access);
+
+        [Obsolete("This method has been deprecated. Please use new Create(SafeFileHandle handle, FileAccess access) instead, and optionally make a new SafeFileHandle with ownsHandle=false if needed. http://go.microsoft.com/fwlink/?linkid=14202")]
+        public Stream Create(IntPtr handle, FileAccess access, bool ownsHandle)
+            => new FileStream(handle, access, ownsHandle);
+
+        [Obsolete("This method has been deprecated. Please use new Create(SafeFileHandle handle, FileAccess access, int bufferSize) instead, and optionally make a new SafeFileHandle with ownsHandle=false if needed. http://go.microsoft.com/fwlink/?linkid=14202")]
+        public Stream Create(IntPtr handle, FileAccess access, bool ownsHandle, int bufferSize)
+            => new FileStream(handle, access, ownsHandle, bufferSize);
+
+        [Obsolete("This method has been deprecated. Please use new Create(SafeFileHandle handle, FileAccess access, int bufferSize, bool isAsync) instead, and optionally make a new SafeFileHandle with ownsHandle=false if needed. http://go.microsoft.com/fwlink/?linkid=14202")]
+        public Stream Create(IntPtr handle, FileAccess access, bool ownsHandle, int bufferSize, bool isAsync)
+            =>  new FileStream(handle, access, ownsHandle, bufferSize, isAsync);
+#endif
+    }
+}

System.IO.Abstractions/FileSystem.cs

@@ -21,6 +21,12 @@ public IFileInfoFactory FileInfo
             get { return fileInfoFactory ?? (fileInfoFactory = new FileInfoFactory()); }
         }
 
+        FileStreamFactory fileStreamFactory;
+        public IFileStreamFactory FileStream
+        {
+            get { return fileStreamFactory ?? (fileStreamFactory = new FileStreamFactory()); }
+        }
+
         PathBase path;
         public PathBase Path
         {

System.IO.Abstractions/IFileStreamFactory.cs

@@ -0,0 +1,46 @@
+using System.Security.AccessControl;
+using Microsoft.Win32.SafeHandles;
+
+namespace System.IO.Abstractions
+{
+    public interface IFileStreamFactory
+    {
+        Stream Create(string path, FileMode mode);
+
+        Stream Create(string path, FileMode mode, FileAccess access);
+
+        Stream Create(string path, FileMode mode, FileAccess access, FileShare share);
+
+        Stream Create(string path, FileMode mode, FileAccess access, FileShare share, int bufferSize);
+
+        Stream Create(string path, FileMode mode, FileAccess access, FileShare share, int bufferSize, FileOptions options);
+
+        Stream Create(string path, FileMode mode, FileAccess access, FileShare share, int bufferSize, bool useAsync);
+
+        Stream Create(SafeFileHandle handle, FileAccess access);
+
+        Stream Create(SafeFileHandle handle, FileAccess access, int bufferSize);
+
+        Stream Create(SafeFileHandle handle, FileAccess access, int bufferSize, bool isAsync);
+
+#if NET40
+        Stream Create(string path, FileMode mode, FileSystemRights rights, FileShare share, int bufferSize, FileOptions options, FileSecurity fileSecurity);
+
+        Stream Create(string path, FileMode mode, FileSystemRights rights, FileShare share, int bufferSize, FileOptions options);
+#endif
+
+#if NET40 || NETSTANDARD_20
+        [Obsolete("This method has been deprecated. Please use new Create(SafeFileHandle handle, FileAccess access) instead. http://go.microsoft.com/fwlink/?linkid=14202")]
+        Stream Create(IntPtr handle, FileAccess access);
+
+        [Obsolete("This method has been deprecated. Please use new Create(SafeFileHandle handle, FileAccess access) instead, and optionally make a new SafeFileHandle with ownsHandle=false if needed. http://go.microsoft.com/fwlink/?linkid=14202")]
+        Stream Create(IntPtr handle, FileAccess access, bool ownsHandle);
+
+        [Obsolete("This method has been deprecated. Please use new Create(SafeFileHandle handle, FileAccess access, int bufferSize) instead, and optionally make a new SafeFileHandle with ownsHandle=false if needed. http://go.microsoft.com/fwlink/?linkid=14202")]
+        Stream Create(IntPtr handle, FileAccess access, bool ownsHandle, int bufferSize);
+
+        [Obsolete("This method has been deprecated. Please use new Create(SafeFileHandle handle, FileAccess access, int bufferSize, bool isAsync) instead, and optionally make a new SafeFileHandle with ownsHandle=false if needed. http://go.microsoft.com/fwlink/?linkid=14202")]
+        Stream Create(IntPtr handle, FileAccess access, bool ownsHandle, int bufferSize, bool isAsync);
+#endif
+    }
+}

System.IO.Abstractions/IFileSystem.cs

@@ -5,6 +5,7 @@ public interface IFileSystem
         FileBase File { get; }
         DirectoryBase Directory { get; }
         IFileInfoFactory FileInfo { get; }
+        IFileStreamFactory FileStream { get; }
         PathBase Path { get; }
         IDirectoryInfoFactory DirectoryInfo { get; }
         IDriveInfoFactory DriveInfo { get; }

System.IO.Abstractions/System.IO.Abstractions.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
         <TargetFrameworks>net40;netstandard1.4;netstandard2.0;</TargetFrameworks>

TestHelpers.Tests/MockFileStreamFactoryTests.cs

@@ -0,0 +1,45 @@
+using System.Collections.Generic;
+using NUnit.Framework; 
+
+namespace System.IO.Abstractions.TestingHelpers.Tests
+{
+    [TestFixture]
+    public class MockFileStreamFactoryTests
+    {
+        [Test]
+        [TestCase(FileMode.Create)]
+        [TestCase(FileMode.Append)]
+        public void MockFileStreamFactory_CreateForExistingFile_ShouldReturnStream(FileMode fileMode)
+        {
+            // Arrange
+            var fileSystem = new MockFileSystem(new Dictionary<string, MockFileData>
+            {
+                { @"c:\existing.txt", MockFileData.NullObject }
+            });
+
+            var fileStreamFactory = new MockFileStreamFactory(fileSystem);
+
+            // Act
+            var result = fileStreamFactory.Create(@"c:\existing.txt", fileMode);
+
+            // Assert
+            Assert.IsNotNull(result);
+        }
+
+        [Test]
+        [TestCase(FileMode.Create)]
+        [TestCase(FileMode.Append)]
+        public void MockFileStreamFactory_CreateForNonExistingFile_ShouldReturnStream(FileMode fileMode)
+        {
+            // Arrange
+            var fileSystem = new MockFileSystem();
+            var fileStreamFactory = new MockFileStreamFactory(fileSystem);
+
+            // Act
+            var result = fileStreamFactory.Create(@"c:\not_existing.txt", fileMode);
+
+            // Assert
+            Assert.IsNotNull(result);
+        }
+    }
+}

TestingHelpers/MockFileStreamFactory.cs

@@ -0,0 +1,83 @@
+using System.Security.AccessControl;
+using Microsoft.Win32.SafeHandles;
+
+namespace System.IO.Abstractions.TestingHelpers
+{
+    [Serializable]
+    public class MockFileStreamFactory : IFileStreamFactory
+    {
+        private readonly IMockFileDataAccessor mockFileSystem;
+
+        public MockFileStreamFactory(IMockFileDataAccessor mockFileSystem)
+            => this.mockFileSystem = mockFileSystem ?? throw new ArgumentNullException(nameof(mockFileSystem));
+
+        public Stream Create(string path, FileMode mode)
+            => new MockFileStream(mockFileSystem, path, GetStreamType(mode));
+
+        public Stream Create(string path, FileMode mode, FileAccess access)
+            => new MockFileStream(mockFileSystem, path, GetStreamType(mode, access));
+
+        public Stream Create(string path, FileMode mode, FileAccess access, FileShare share)
+            => new MockFileStream(mockFileSystem, path, GetStreamType(mode, access));
+
+        public Stream Create(string path, FileMode mode, FileAccess access, FileShare share, int bufferSize)
+            => new MockFileStream(mockFileSystem, path, GetStreamType(mode, access));
+
+        public Stream Create(string path, FileMode mode, FileAccess access, FileShare share, int bufferSize, FileOptions options)
+            => new MockFileStream(mockFileSystem, path, GetStreamType(mode, access));
+
+        public Stream Create(string path, FileMode mode, FileAccess access, FileShare share, int bufferSize, bool useAsync)
+            => new MockFileStream(mockFileSystem, path, GetStreamType(mode, access));
+
+#if NET40
+        public Stream Create(string path, FileMode mode, FileSystemRights rights, FileShare share, int bufferSize, FileOptions options, FileSecurity fileSecurity)
+            => new MockFileStream(mockFileSystem, path, GetStreamType(mode));
+
+        public Stream Create(string path, FileMode mode, FileSystemRights rights, FileShare share, int bufferSize, FileOptions options)
+            => new MockFileStream(mockFileSystem, path, GetStreamType(mode));
+#endif
+
+#if NET40 || NETSTANDARD_20
+        [Obsolete("This method has been deprecated. Please use new Create(SafeFileHandle handle, FileAccess access) instead. http://go.microsoft.com/fwlink/?linkid=14202")]
+        public Stream Create(IntPtr handle, FileAccess access)
+            => new MockFileStream(mockFileSystem, handle.ToString(), GetStreamType(FileMode.Append, access));
+
+        [Obsolete("This method has been deprecated. Please use new Create(SafeFileHandle handle, FileAccess access) instead, and optionally make a new SafeFileHandle with ownsHandle=false if needed. http://go.microsoft.com/fwlink/?linkid=14202")]
+        public Stream Create(IntPtr handle, FileAccess access, bool ownsHandle)
+            => new MockFileStream(mockFileSystem, handle.ToString(), GetStreamType(FileMode.Append, access));
+
+        [Obsolete("This method has been deprecated. Please use new Create(SafeFileHandle handle, FileAccess access, int bufferSize) instead, and optionally make a new SafeFileHandle with ownsHandle=false if needed. http://go.microsoft.com/fwlink/?linkid=14202")]
+        public Stream Create(IntPtr handle, FileAccess access, bool ownsHandle, int bufferSize)
+            => new MockFileStream(mockFileSystem, handle.ToString(), GetStreamType(FileMode.Append, access));
+
+        [Obsolete("This method has been deprecated. Please use new Create(SafeFileHandle handle, FileAccess access, int bufferSize, bool isAsync) instead, and optionally make a new SafeFileHandle with ownsHandle=false if needed. http://go.microsoft.com/fwlink/?linkid=14202")]
+        public Stream Create(IntPtr handle, FileAccess access, bool ownsHandle, int bufferSize, bool isAsync)
+            => new MockFileStream(mockFileSystem, handle.ToString(), GetStreamType(FileMode.Append, access));
+#endif
+
+        public Stream Create(SafeFileHandle handle, FileAccess access)
+            => new MockFileStream(mockFileSystem, handle.ToString(), GetStreamType(FileMode.Append, access));
+
+        public Stream Create(SafeFileHandle handle, FileAccess access, int bufferSize)
+            => new MockFileStream(mockFileSystem, handle.ToString(), GetStreamType(FileMode.Append, access));
+
+        public Stream Create(SafeFileHandle handle, FileAccess access, int bufferSize, bool isAsync)
+            => new MockFileStream(mockFileSystem, handle.ToString(), GetStreamType(FileMode.Append, access));
+
+        private static MockFileStream.StreamType GetStreamType(FileMode mode, FileAccess access = FileAccess.ReadWrite)
+        {
+            if (access == FileAccess.Read)
+            {
+                return MockFileStream.StreamType.READ;
+            }
+            else if (mode == FileMode.Append) 
+            {
+                return MockFileStream.StreamType.APPEND;
+            }
+            else
+            {
+                return MockFileStream.StreamType.WRITE;
+            }
+        }
+    }
+}

TestingHelpers/MockFileSystem.cs

@@ -10,7 +10,6 @@ namespace System.IO.Abstractions.TestingHelpers
     public class MockFileSystem : IFileSystem, IMockFileDataAccessor
     {
         private readonly IDictionary<string, MockFileData> files;
-
         [NonSerialized]
         private readonly PathVerifier pathVerifier;
 
@@ -26,10 +25,12 @@ public MockFileSystem(IDictionary<string, MockFileData> files, string currentDir
             pathVerifier = new PathVerifier(this);
 
             this.files = new Dictionary<string, MockFileData>(StringComparer.OrdinalIgnoreCase);
+
             Path = new MockPath(this);
             File = new MockFile(this);
             Directory = new MockDirectory(this, File, currentDirectory);
             FileInfo = new MockFileInfoFactory(this);
+            FileStream = new MockFileStreamFactory(this);
             DirectoryInfo = new MockDirectoryInfoFactory(this);
             DriveInfo = new MockDriveInfoFactory(this);
             FileSystemWatcher = new MockFileSystemWatcherFactory();
@@ -49,6 +50,8 @@ public MockFileSystem(IDictionary<string, MockFileData> files, string currentDir
 
         public IFileInfoFactory FileInfo { get; }
 
+        public IFileStreamFactory FileStream { get; }
+
         public PathBase Path { get; }
 
         public IDirectoryInfoFactory DirectoryInfo { get; }

TestingHelpers/TestingHelpers.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
     <PropertyGroup>
         <TargetFrameworks>net40;netstandard1.4;netstandard2.0;</TargetFrameworks>
         <PackageId>System.IO.Abstractions.TestingHelpers</PackageId>