Add Directory.CheckWriteAccess and File.CheckWriteAccess

Directory.Packages.props

@@ -12,5 +12,6 @@
     <PackageVersion Include="PolyShim" Version="2.8.2" />
     <PackageVersion Include="xunit" Version="2.9.2" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.8.2" />
+    <PackageVersion Include="Xunit.SkippableFact" Version="1.5.61" />
   </ItemGroup>
 </Project>

PowerKit.Tests/DirectoryExtensionsTests.cs

@@ -1,3 +1,4 @@
+using System;
 using System.IO;
 using FluentAssertions;
 using PowerKit;
@@ -8,6 +9,44 @@ namespace PowerKit.Tests;
 
 public class DirectoryExtensionsTests
 {
+    [Fact]
+    public void CheckWriteAccess_Test()
+    {
+        // Arrange
+        using var tempDir = TempDirectory.Create();
+
+        // Act
+        var result = Directory.CheckWriteAccess(tempDir.Path);
+
+        // Assert
+        result.Should().BeTrue();
+    }
+
+    [SkippableFact]
+    public void CheckWriteAccess_ReadOnly_Test()
+    {
+        // FileAttributes.ReadOnly removes write bits on Unix but has no effect on directories on Windows
+        Skip.If(OperatingSystem.IsWindows() || Environment.IsPrivilegedProcess);
+
+        // Arrange
+        using var tempDir = TempDirectory.Create();
+        var dirInfo = new DirectoryInfo(tempDir.Path);
+        dirInfo.Attributes |= FileAttributes.ReadOnly;
+
+        try
+        {
+            // Act
+            var result = Directory.CheckWriteAccess(tempDir.Path);
+
+            // Assert
+            result.Should().BeFalse();
+        }
+        finally
+        {
+            dirInfo.Attributes &= ~FileAttributes.ReadOnly;
+        }
+    }
+
     [Fact]
     public void Reset_Test()
     {

PowerKit.Tests/FileExtensionsTests.cs

@@ -1,3 +1,4 @@
+using System;
 using System.IO;
 using System.Threading.Tasks;
 using FluentAssertions;
@@ -9,6 +10,58 @@ namespace PowerKit.Tests;
 
 public class FileExtensionsTests
 {
+    [Fact]
+    public void CheckWriteAccess_Test()
+    {
+        // Arrange
+        using var tempFile = TempFile.Create();
+
+        // Act
+        var result = File.CheckWriteAccess(tempFile.Path);
+
+        // Assert
+        result.Should().BeTrue();
+    }
+
+    [SkippableFact]
+    public void CheckWriteAccess_ReadOnly_Test()
+    {
+        // Privileged processes can write to read-only files on Unix
+        Skip.If(Environment.IsPrivilegedProcess);
+
+        // Arrange
+        using var tempFile = TempFile.Create();
+        File.SetAttributes(tempFile.Path, File.GetAttributes(tempFile.Path) | FileAttributes.ReadOnly);
+
+        try
+        {
+            // Act
+            var result = File.CheckWriteAccess(tempFile.Path);
+
+            // Assert
+            result.Should().BeFalse();
+        }
+        finally
+        {
+            File.SetAttributes(tempFile.Path, File.GetAttributes(tempFile.Path) & ~FileAttributes.ReadOnly);
+        }
+    }
+
+    [Fact]
+    public void CheckWriteAccess_NonExistent_Test()
+    {
+        // Arrange
+        using var tempDir = TempDirectory.Create();
+        var path = Path.Combine(tempDir.Path, "new-file.txt");
+
+        // Act
+        var result = File.CheckWriteAccess(path);
+
+        // Assert
+        result.Should().BeTrue();
+        File.Exists(path).Should().BeFalse();
+    }
+
     [Fact]
     public void TryDelete_Test()
     {

PowerKit.Tests/PowerKit.Tests.csproj

@@ -23,6 +23,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" />
     <PackageReference Include="xunit" />
     <PackageReference Include="xunit.runner.visualstudio" />
+    <PackageReference Include="Xunit.SkippableFact" />
   </ItemGroup>
 
 </Project>

PowerKit/Extensions/DirectoryExtensions.cs

@@ -1,3 +1,4 @@
+using System;
 using System.IO;
 
 namespace PowerKit.Extensions;
@@ -36,5 +37,27 @@ public static bool TryDelete(string path, bool recursive = false)
                 return false;
             }
         }
+
+        /// <summary>
+        /// Checks if it's possible to write to the specified directory.
+        /// </summary>
+        public static bool CheckWriteAccess(string path)
+        {
+            var tempFilePath = Path.Combine(path, Guid.NewGuid().ToString());
+
+            try
+            {
+                using var tempFile = File.Create(tempFilePath);
+                return true;
+            }
+            catch (UnauthorizedAccessException)
+            {
+                return false;
+            }
+            finally
+            {
+                File.TryDelete(tempFilePath);
+            }
+        }
     }
 }

PowerKit/Extensions/FileExtensions.cs

@@ -31,6 +31,31 @@ public static bool TryDelete(string path)
             }
         }
 
+        /// <summary>
+        /// Checks if it's possible to write to the specified file.
+        /// </summary>
+        public static bool CheckWriteAccess(string path)
+        {
+            var wasExisting = File.Exists(path);
+
+            try
+            {
+                using var stream = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Write, FileShare.ReadWrite);
+                return true;
+            }
+            catch (UnauthorizedAccessException)
+            {
+                return false;
+            }
+            finally
+            {
+                if (!wasExisting)
+                {
+                    File.TryDelete(path);
+                }
+            }
+        }
+
         /// <summary>
         /// Creates a file at the specified path and fills it with zeroes.
         /// </summary>