Add tests for FileStream span-based overrides (#23481)

2 files changed, 193 insertions, 0 deletions

diff --git a/src/System.IO.FileSystem/tests/FileStream/ReadWriteSpan.netcoreapp.cs b/src/System.IO.FileSystem/tests/FileStream/ReadWriteSpan.netcoreapp.cs
new file mode 100644
index 0000000000..3a67c5c9d0
--- /dev/null
+++ b/src/System.IO.FileSystem/tests/FileStream/ReadWriteSpan.netcoreapp.cs
@@ -0,0 +1,192 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Linq;
+using Xunit;
+
+namespace System.IO.Tests
+{
+    public abstract class FileStream_ReadWrite_Span : FileSystemTest
+    {
+        protected abstract FileStream CreateFileStream(string path, FileMode mode, FileAccess access = FileAccess.ReadWrite);
+
+        [Fact]
+        public void DisposedStream_ReadWrite_Throws()
+        {
+            var fs = CreateFileStream(GetTestFilePath(), FileMode.Create);
+            fs.Dispose();
+            Assert.Throws<ObjectDisposedException>(() => fs.Read(new Span<byte>(new byte[1])));
+            Assert.Throws<ObjectDisposedException>(() => fs.Write(new Span<byte>(new byte[1])));
+        }
+
+        [Fact]
+        public void EmptyFile_Read_Succeeds()
+        {
+            using (var fs = CreateFileStream(GetTestFilePath(), FileMode.Create))
+            {
+                // use a recognizable pattern
+                var buffer = (byte[])TestBuffer.Clone();
+
+                Assert.Equal(0, fs.Read(Span<byte>.Empty));
+                Assert.Equal(0, fs.Read(new Span<byte>(buffer, 0, 1)));
+                Assert.Equal(TestBuffer, buffer);
+
+                Assert.Equal(0, fs.Read(new Span<byte>(buffer, 0, buffer.Length)));
+                Assert.Equal(TestBuffer, buffer);
+
+                Assert.Equal(0, fs.Read(new Span<byte>(buffer, buffer.Length - 1, 1)));
+                Assert.Equal(TestBuffer, buffer);
+
+                Assert.Equal(0, fs.Read(new Span<byte>(buffer, buffer.Length / 2, buffer.Length - buffer.Length / 2)));
+                Assert.Equal(TestBuffer, buffer);
+            }
+        }
+
+        [Fact]
+        public void NonEmptyFile_Read_GetsExpectedData()
+        {
+            string fileName = GetTestFilePath();
+            File.WriteAllBytes(fileName, TestBuffer);
+
+            using (var fs = CreateFileStream(fileName, FileMode.Open))
+            {
+                var buffer = new byte[TestBuffer.Length];
+                Assert.Equal(TestBuffer.Length, fs.Read(new Span<byte>(buffer, 0, buffer.Length)));
+                Assert.Equal(TestBuffer, buffer);
+
+                // Larger than needed buffer, read into beginning, rest remains untouched
+                fs.Position = 0;
+                buffer = new byte[TestBuffer.Length * 2];
+                Assert.Equal(TestBuffer.Length, fs.Read(new Span<byte>(buffer)));
+                Assert.Equal(TestBuffer, buffer.Take(TestBuffer.Length));
+                Assert.Equal(new byte[buffer.Length - TestBuffer.Length], buffer.Skip(TestBuffer.Length));
+
+                // Larger than needed buffer, read into middle, beginning and end remain untouched
+                fs.Position = 0;
+                buffer = new byte[TestBuffer.Length * 2];
+                Assert.Equal(TestBuffer.Length, fs.Read(new Span<byte>(buffer, 2, buffer.Length - 2)));
+                Assert.Equal(TestBuffer, buffer.Skip(2).Take(TestBuffer.Length));
+                Assert.Equal(new byte[2], buffer.Take(2));
+                Assert.Equal(new byte[buffer.Length - TestBuffer.Length - 2], buffer.Skip(2 + TestBuffer.Length));
+            }
+        }
+
+        [Fact]
+        public void ReadOnly_Write_Throws()
+        {
+            string fileName = GetTestFilePath();
+            File.WriteAllBytes(fileName, TestBuffer);
+
+            using (var fs = CreateFileStream(fileName, FileMode.Open, FileAccess.Read))
+            {
+                Assert.Throws<NotSupportedException>(() => fs.Write(new Span<byte>(new byte[1])));
+                fs.Dispose();
+                Assert.Throws<ObjectDisposedException>(() => fs.Write(new Span<byte>(new byte[1]))); // Disposed checking happens first
+            }
+        }
+
+        [Fact]
+        public void WriteOnly_Read_Throws()
+        {
+            using (var fs = CreateFileStream(GetTestFilePath(), FileMode.Create, FileAccess.Write))
+            {
+                Assert.Throws<NotSupportedException>(() => fs.Read(new Span<byte>(new byte[1])));
+                fs.Dispose();
+                Assert.Throws<ObjectDisposedException>(() => fs.Read(new Span<byte>(new byte[1]))); // Disposed checking happens first
+            }
+        }
+
+        [Fact]
+        public void EmptyWrites_NoDataWritten()
+        {
+            using (var fs = CreateFileStream(GetTestFilePath(), FileMode.Create))
+            {
+                fs.Write(Span<byte>.Empty);
+                Assert.Equal(0, fs.Length);
+                Assert.Equal(0, fs.Position);
+            }
+        }
+
+        [Fact]
+        public void NonEmptyWrite_WritesExpectedData()
+        {
+            using (var fs = CreateFileStream(GetTestFilePath(), FileMode.Create))
+            {
+                fs.Write(new Span<byte>(TestBuffer));
+                Assert.Equal(TestBuffer.Length, fs.Length);
+                Assert.Equal(TestBuffer.Length, fs.Position);
+
+                fs.Position = 0;
+                var buffer = new byte[TestBuffer.Length];
+                Assert.Equal(TestBuffer.Length, fs.Read(new Span<byte>(buffer)));
+                Assert.Equal(TestBuffer, buffer);
+            }
+        }
+    }
+
+    public class Sync_FileStream_ReadWrite_Span : FileStream_ReadWrite_Span
+    {
+        protected override FileStream CreateFileStream(string path, FileMode mode, FileAccess access) =>
+            new FileStream(path, mode, access, FileShare.None, 0x1000, FileOptions.None);
+    }
+
+    public class Async_FileStream_ReadWrite_Span : FileStream_ReadWrite_Span
+    {
+        protected override FileStream CreateFileStream(string path, FileMode mode, FileAccess access) =>
+            new FileStream(path, mode, access, FileShare.None, 0x1000, FileOptions.Asynchronous);
+    }
+
+    public sealed class Sync_DerivedFileStream_ReadWrite_Span : Sync_FileStream_ReadWrite_Span
+    {
+        protected override FileStream CreateFileStream(string path, FileMode mode, FileAccess access) =>
+            new DerivedFileStream(path, mode, access, FileShare.None, 0x1000, FileOptions.None);
+
+        [Fact]
+        public void CallSpanReadWriteOnDerivedFileStream_ArrayMethodsUsed()
+        {
+            using (var fs = (DerivedFileStream)CreateFileStream(GetTestFilePath(), FileMode.Create, FileAccess.ReadWrite))
+            {
+                Assert.False(fs.WriteArrayInvoked);
+                Assert.False(fs.ReadArrayInvoked);
+
+                fs.Write(new ReadOnlySpan<byte>(new byte[1]));
+                Assert.True(fs.WriteArrayInvoked);
+                Assert.False(fs.ReadArrayInvoked);
+
+                fs.Position = 0;
+                fs.Read(new Span<byte>(new byte[1]));
+                Assert.True(fs.WriteArrayInvoked);
+                Assert.True(fs.ReadArrayInvoked);
+            }
+        }
+    }
+
+    public sealed class Async_DerivedFileStream_ReadWrite_Span : Async_FileStream_ReadWrite_Span
+    {
+        protected override FileStream CreateFileStream(string path, FileMode mode, FileAccess access) =>
+            new DerivedFileStream(path, mode, access, FileShare.None, 0x1000, FileOptions.Asynchronous);
+    }
+
+    internal sealed class DerivedFileStream : FileStream
+    {
+        public bool ReadArrayInvoked = false, WriteArrayInvoked = false;
+
+        public DerivedFileStream(string path, FileMode mode, FileAccess access, FileShare share, int bufferSize, FileOptions options) :
+            base(path, mode, access, share, bufferSize, options)
+        {
+        }
+
+        public override int Read(byte[] array, int offset, int count)
+        {
+            ReadArrayInvoked = true;
+            return base.Read(array, offset, count);
+        }
+
+        public override void Write(byte[] array, int offset, int count)
+        {
+            WriteArrayInvoked = true;
+            base.Write(array, offset, count);
+        }
+    }
+}
diff --git a/src/System.IO.FileSystem/tests/System.IO.FileSystem.Tests.csproj b/src/System.IO.FileSystem/tests/System.IO.FileSystem.Tests.csproj
index bf25500602..e805b9f789 100644
--- a/src/System.IO.FileSystem/tests/System.IO.FileSystem.Tests.csproj
+++ b/src/System.IO.FileSystem/tests/System.IO.FileSystem.Tests.csproj
@@ -51,6 +51,7 @@
     <Compile Include="File\ReadWriteAllLinesAsync.cs" />
     <Compile Include="File\ReadWriteAllBytesAsync.cs" />
     <Compile Include="File\ReadWriteAllTextAsync.cs" />
+    <Compile Include="FileStream\ReadWriteSpan.netcoreapp.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetGroup)' == 'uapaot' or '$(TargetGroup)' == 'uap'">
     <Compile Include="WinRT_BrokeredFunctions.cs" />