fix: copying a file throws if a file handle with ReadWrite share is…

… open (#550)

* Fix copy access
* Adapt tests for Linux/MacOS to handle the different behaviour:
  When FileShare.Write is used for the FileStream, it throws only on Windows, but not on Linux or MacOS.

Source/Testably.Abstractions.Testing/Storage/InMemoryStorage.cs

@@ -58,7 +58,7 @@ public InMemoryStorage(MockFileSystem fileSystem)
 			throw ExceptionFactory.AccessToPathDenied(source.FullPath);
 		}
 
-		using (_ = sourceContainer.RequestAccess(FileAccess.ReadWrite, FileShare.None))
+		using (_ = sourceContainer.RequestAccess(FileAccess.Read, FileShare.ReadWrite))
 		{
 			if (overwrite &&
 			    _containers.TryRemove(destination,

Tests/Testably.Abstractions.Tests/FileSystem/File/CopyTests.cs

@@ -263,6 +263,37 @@ public void Copy_ShouldCopyFileWithContent(
 			.Which.HasContent(contents);
 	}
 
+	[SkippableTheory]
+	[InlineAutoData(FileAccess.Read, FileShare.Read)]
+	[InlineAutoData(FileAccess.Read, FileShare.ReadWrite)]
+	[InlineAutoData(FileAccess.Read, FileShare.Write)]
+	[InlineAutoData(FileAccess.ReadWrite, FileShare.Read)]
+	[InlineAutoData(FileAccess.ReadWrite, FileShare.ReadWrite)]
+	[InlineAutoData(FileAccess.ReadWrite, FileShare.Write)]
+	[InlineAutoData(FileAccess.Write, FileShare.Read)]
+	[InlineAutoData(FileAccess.Write, FileShare.ReadWrite)]
+	[InlineAutoData(FileAccess.Write, FileShare.Write)]
+	public void Copy_SourceAccessedWithReadShare_ShouldNotThrow(
+		FileAccess fileAccess,
+		FileShare fileShare,
+		string sourcePath,
+		string destinationPath,
+		string sourceContents)
+	{
+		Skip.If(Test.RunsOnWindows && fileShare == FileShare.Write);
+
+		FileSystem.Initialize().WithFile(sourcePath)
+			.Which(f => f.HasStringContent(sourceContents));
+		using (FileSystem.FileStream
+			.New(sourcePath, FileMode.Open, fileAccess, fileShare))
+		{
+			FileSystem.File.Copy(sourcePath, destinationPath);
+		}
+
+		FileSystem.File.Exists(destinationPath).Should().BeTrue();
+		FileSystem.File.ReadAllText(destinationPath).Should().Be(sourceContents);
+	}
+
 	[SkippableTheory]
 	[AutoData]
 	public void Copy_SourceIsDirectory_ShouldThrowUnauthorizedAccessException_AndNotCopyFile(
@@ -286,14 +317,18 @@ public void Copy_SourceIsDirectory_ShouldThrowUnauthorizedAccessException_AndNot
 	}
 
 	[SkippableTheory]
-	[AutoData]
+	[InlineAutoData(FileShare.None)]
+	[InlineAutoData(FileShare.Write)]
 	public void Copy_SourceLocked_ShouldThrowIOException(
+		FileShare fileShare,
 		string sourceName,
 		string destinationName)
 	{
+		Skip.If(!Test.RunsOnWindows && fileShare == FileShare.Write);
+
 		FileSystem.File.WriteAllText(sourceName, null);
 		using FileSystemStream stream = FileSystem.File.Open(sourceName, FileMode.Open,
-			FileAccess.Read, FileShare.None);
+			FileAccess.Read, fileShare);
 
 		Exception? exception = Record.Exception(() =>
 		{