feat: enable assertions on IFileSystemInfo (#51)

Enable assertions directly on `IFileSystemInfo`, e.g. when returned from
`ResolveLinkTarget`.

Author: vbreuss

Source/Testably.Abstractions.FluentAssertions/FileSystemExtensions.cs

@@ -19,6 +19,13 @@ public static DirectoryInfoAssertions Should(this IDirectoryInfo? instance)
 	public static FileInfoAssertions Should(this IFileInfo? instance)
 		=> new(instance);
 
+	/// <summary>
+	///     Returns a <see cref="FileAssertions" /> object that can be used to
+	///     assert the current <see cref="IFileInfo" />.
+	/// </summary>
+	public static FileSystemInfoAssertions Should(this IFileSystemInfo? instance)
+		=> new(instance);
+
 	/// <summary>
 	///     Returns a <see cref="FileSystemAssertions" /> object that can be used to
 	///     assert the current <see cref="IFileSystem" />.

Source/Testably.Abstractions.FluentAssertions/FileSystemInfoAssertions.cs

@@ -1,5 +1,20 @@
 namespace Testably.Abstractions.FluentAssertions;
 
+/// <summary>
+///     Assertions on <see cref="IFileSystemInfo" />.
+/// </summary>
+public class FileSystemInfoAssertions :
+	FileSystemInfoAssertions<IFileSystemInfo, FileSystemInfoAssertions>
+{
+	/// <inheritdoc cref="ReferenceTypeAssertions{TSubject,TAssertions}.Identifier" />
+	protected override string Identifier => "file system info";
+
+	internal FileSystemInfoAssertions(IFileSystemInfo? instance)
+		: base(instance)
+	{
+	}
+}
+
 /// <summary>
 ///     Assertions on <see cref="IFileSystemInfo" />.
 /// </summary>

Tests/Testably.Abstractions.FluentAssertions.Tests/FileSystemInfoAssertionsTests.cs

@@ -149,6 +149,45 @@ public void Exist_ForFileInfo_WithSameDirectory_ShouldThrow(
 			.Be($"Expected file \"{fileName}\" to exist {because}, but it did not.");
 	}
 
+#if NET
+	[SkippableTheory]
+	[AutoData]
+	public void Exist_ForFileSystemInfo_WithExistingFile_ShouldNotThrow(
+		string path, string pathToTarget, string because)
+	{
+		MockFileSystem fileSystem = new();
+		string targetFullPath = fileSystem.Path.GetFullPath(pathToTarget);
+		fileSystem.Directory.CreateDirectory(pathToTarget);
+		fileSystem.Directory.CreateSymbolicLink(path, targetFullPath);
+		IFileSystemInfo? sut =
+			fileSystem.Directory.ResolveLinkTarget(path, false);
+
+		sut.Should().Exist(because);
+	}
+
+	[SkippableTheory]
+	[AutoData]
+	public void Exist_ForFileSystemInfo_WithoutExistingFile_ShouldThrow(
+		string path, string pathToTarget, string because)
+	{
+		MockFileSystem fileSystem = new();
+		string targetFullPath = fileSystem.Path.GetFullPath(pathToTarget);
+		fileSystem.Directory.CreateSymbolicLink(path, targetFullPath);
+		IFileSystemInfo? sut =
+			fileSystem.Directory.ResolveLinkTarget(path, false);
+
+		Exception? exception = Record.Exception(() =>
+		{
+			sut.Should().Exist(because);
+		});
+
+		exception.Should().NotBeNull();
+		exception!.Message.Should()
+			.Be(
+				$"Expected file system info \"{pathToTarget}\" to exist {because}, but it did not.");
+	}
+#endif
+
 	[Theory]
 	[AutoData]
 	public void NotExist_ForDirectoryInfo_Null_ShouldThrow(string because)
@@ -275,4 +314,43 @@ public void NotExist_ForFileInfo_WithSameDirectory_ShouldNotThrow(
 
 		sut.Should().NotExist(because);
 	}
+
+#if NET
+	[SkippableTheory]
+	[AutoData]
+	public void NotExist_ForFileSystemInfo_WithExistingFile_ShouldThrow(
+		string path, string pathToTarget, string because)
+	{
+		MockFileSystem fileSystem = new();
+		string targetFullPath = fileSystem.Path.GetFullPath(pathToTarget);
+		fileSystem.Directory.CreateDirectory(pathToTarget);
+		fileSystem.Directory.CreateSymbolicLink(path, targetFullPath);
+		IFileSystemInfo? sut =
+			fileSystem.Directory.ResolveLinkTarget(path, false);
+
+		Exception? exception = Record.Exception(() =>
+		{
+			sut.Should().NotExist(because);
+		});
+
+		exception.Should().NotBeNull();
+		exception!.Message.Should()
+			.Be(
+				$"Expected file system info \"{pathToTarget}\" not to exist {because}, but it did.");
+	}
+
+	[SkippableTheory]
+	[AutoData]
+	public void NotExist_ForFileSystemInfo_WithoutExistingFile_ShouldNotThrow(
+		string path, string pathToTarget, string because)
+	{
+		MockFileSystem fileSystem = new();
+		string targetFullPath = fileSystem.Path.GetFullPath(pathToTarget);
+		fileSystem.Directory.CreateSymbolicLink(path, targetFullPath);
+		IFileSystemInfo? sut =
+			fileSystem.Directory.ResolveLinkTarget(path, false);
+
+		sut.Should().NotExist(because);
+	}
+#endif
 }