Fix file attrbutes not being set

src/MarkdownSnippets/FileEx.cs

@@ -48,15 +48,16 @@ public static void ClearReadOnly(string path)
             return;
         }
 
-        new FileInfo(path)
+        var attributes = File.GetAttributes(path);
+        if ((attributes & FileAttributes.ReadOnly) != 0)
         {
-            IsReadOnly = false
-        };
+            File.SetAttributes(path, attributes & ~FileAttributes.ReadOnly);
+        }
     }
 
-    public static void MakeReadOnly(string path) =>
-        new FileInfo(path)
-        {
-            IsReadOnly = true
-        };
+    public static void MakeReadOnly(string path)
+    {
+        var attributes = File.GetAttributes(path);
+        File.SetAttributes(path, attributes | FileAttributes.ReadOnly);
+    }
 }

src/Tests/FileExTests.cs

@@ -1,5 +1,72 @@
 public class FileExTests
 {
+    [Fact]
+    public void MakeReadOnly_SetsReadOnlyAttribute()
+    {
+        var tempFile = Path.GetTempFileName();
+        try
+        {
+            FileEx.MakeReadOnly(tempFile);
+
+            var attributes = File.GetAttributes(tempFile);
+            Assert.True((attributes & FileAttributes.ReadOnly) != 0);
+        }
+        finally
+        {
+            File.SetAttributes(tempFile, FileAttributes.Normal);
+            File.Delete(tempFile);
+        }
+    }
+
+    [Fact]
+    public void ClearReadOnly_RemovesReadOnlyAttribute()
+    {
+        var tempFile = Path.GetTempFileName();
+        try
+        {
+            File.SetAttributes(tempFile, File.GetAttributes(tempFile) | FileAttributes.ReadOnly);
+
+            FileEx.ClearReadOnly(tempFile);
+
+            var attributes = File.GetAttributes(tempFile);
+            Assert.False((attributes & FileAttributes.ReadOnly) != 0);
+        }
+        finally
+        {
+            File.SetAttributes(tempFile, FileAttributes.Normal);
+            File.Delete(tempFile);
+        }
+    }
+
+    [Fact]
+    public void ClearReadOnly_DoesNothingIfFileDoesNotExist()
+    {
+        var nonExistentFile = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString());
+
+        FileEx.ClearReadOnly(nonExistentFile);
+
+        Assert.False(File.Exists(nonExistentFile));
+    }
+
+    [Fact]
+    public void MakeReadOnly_ThenClearReadOnly_RoundTrip()
+    {
+        var tempFile = Path.GetTempFileName();
+        try
+        {
+            FileEx.MakeReadOnly(tempFile);
+            Assert.True((File.GetAttributes(tempFile) & FileAttributes.ReadOnly) != 0);
+
+            FileEx.ClearReadOnly(tempFile);
+            Assert.False((File.GetAttributes(tempFile) & FileAttributes.ReadOnly) != 0);
+        }
+        finally
+        {
+            File.SetAttributes(tempFile, FileAttributes.Normal);
+            File.Delete(tempFile);
+        }
+    }
+
     [Fact]
     public void FixFileCapitalization_ReturnsActualCasing()
     {