Refactor DnvmConfigFile to use instance methods

Changed DnvmConfigFile from a static class to a regular class with instance methods. This provides better testability and follows standard OOP patterns.

Usage changes:
- Before: var config = DnvmConfigFile.Read();
- After: var configFile = new DnvmConfigFile(); var config = configFile.Read();

Co-authored-by: agocke <515774+agocke@users.noreply.github.com>

Author: Copilot

src/dnvm/DnvmConfig.cs

@@ -25,15 +25,26 @@ public sealed partial record DnvmConfig
 }
 
 /// <summary>
-/// Static methods for config file operations.
+/// Provides access to the dnvm configuration file.
 /// </summary>
-public static class DnvmConfigFile
+public sealed class DnvmConfigFile
 {
     private const string ConfigFileName = "dnvmConfig.json";
 
     // Allow tests to override the config directory
     public static string? TestConfigDirectory { get; set; }
 
+    private readonly string _configDirectory;
+
+    public DnvmConfigFile() : this(GetConfigDirectory())
+    {
+    }
+
+    internal DnvmConfigFile(string configDirectory)
+    {
+        _configDirectory = configDirectory;
+    }
+
     /// <summary>
     /// Get the platform-specific config directory path.
     /// - Linux: ~/.config/dnvm/ (XDG_CONFIG_HOME/dnvm)
@@ -73,13 +84,12 @@ private static string GetConfigDirectory()
         }
     }
 
-    private static IFileSystem GetConfigFileSystem()
+    private IFileSystem GetConfigFileSystem()
     {
-        var configDir = GetConfigDirectory();
-        Directory.CreateDirectory(configDir);
+        Directory.CreateDirectory(_configDirectory);
         return new SubFileSystem(
             DnvmEnv.PhysicalFs,
-            DnvmEnv.PhysicalFs.ConvertPathFromInternal(configDir));
+            DnvmEnv.PhysicalFs.ConvertPathFromInternal(_configDirectory));
     }
 
     private static UPath ConfigPath => UPath.Root / ConfigFileName;
@@ -88,7 +98,7 @@ private static IFileSystem GetConfigFileSystem()
     /// Reads the config file from the platform-specific config directory.
     /// Returns the default config if the file does not exist.
     /// </summary>
-    public static DnvmConfig Read()
+    public DnvmConfig Read()
     {
         try
         {
@@ -111,7 +121,7 @@ public static DnvmConfig Read()
     /// <summary>
     /// Writes the config file to the platform-specific config directory.
     /// </summary>
-    public static void Write(DnvmConfig config)
+    public void Write(DnvmConfig config)
     {
         var fs = GetConfigFileSystem();
         var tempFileName = $"{ConfigFileName}.{Path.GetRandomFileName()}.tmp";

src/dnvm/UpdateCommand.cs

@@ -126,7 +126,8 @@ public static async Task<Result> UpdateSdks(
     {
         env.Console.WriteLine("Looking for available updates");
         // Check for dnvm updates
-        var config = DnvmConfigFile.Read();
+        var configFile = new DnvmConfigFile();
+        var config = configFile.Read();
         if (await CheckForSelfUpdates(env.HttpClient, env.Console, logger, releasesUrl, config.PreviewsEnabled) is (true, _))
         {
             env.Console.WriteLine("dnvm is out of date. Run 'dnvm update --self' to update dnvm.");
@@ -244,7 +245,8 @@ public async Task<Result> UpdateSelf(Manifest manifest)
             return Result.NotASingleFile;
         }
 
-        var config = DnvmConfigFile.Read();
+        var configFile = new DnvmConfigFile();
+        var config = configFile.Read();
         DnvmReleases.Release release;
         switch (await CheckForSelfUpdates(_env.HttpClient, _env.Console, _logger, _releasesUrl, config.PreviewsEnabled))
         {

test/IntegrationTests/SelfInstallTests.cs

@@ -307,7 +307,8 @@ public Task UpdateSelfPreview() => RunWithServer(async (mockServer, env) =>
 
         // Manually create config file with previews enabled
         var config = new DnvmConfig { PreviewsEnabled = true };
-        DnvmConfigFile.Write(config);
+        var configFile = new DnvmConfigFile();
+        configFile.Write(config);
 
         result = await DnvmRunner.RunAndRestoreEnv(
             env,

test/IntegrationTests/UpdateTests.cs

@@ -53,7 +53,8 @@ public async Task EnablePreviewsAndDownload() => await TestWithServer(async (moc
 
         // Manually create config file with previews enabled
         var config = new DnvmConfig { PreviewsEnabled = true };
-        DnvmConfigFile.Write(config);
+        var configFile = new DnvmConfigFile();
+        configFile.Write(config);
 
         proc = await DnvmRunner.RunAndRestoreEnv(env, SelfInstallTests.DnvmExe,
             $"update --self -v --dnvm-url {mockServer.DnvmReleasesUrl}");