added tests to project

CursorLang.Tests/Infrastructure/TempRegistryKey.cs

@@ -0,0 +1,36 @@
+using Microsoft.Win32;
+
+namespace CursorLang.Tests.Infrastructure;
+
+/// <summary>
+/// A registry key of one test's own. Startup outside a package lives in the
+/// registry, and the real startup list of the user is no place to experiment.
+/// </summary>
+internal sealed class TempRegistryKey : IDisposable
+{
+    private const string Parent = @"Software\CursorLang.Tests";
+
+    private readonly string _path;
+
+    internal TempRegistryKey()
+    {
+        _path = $@"{Parent}\{Guid.NewGuid():N}";
+        Key = Registry.CurrentUser.CreateSubKey(_path);
+    }
+
+    internal RegistryKey Key { get; }
+
+    public void Dispose()
+    {
+        Key.Dispose();
+
+        try
+        {
+            Registry.CurrentUser.DeleteSubKeyTree(_path, throwOnMissingSubKey: false);
+        }
+        catch (Exception e) when (e is System.Security.SecurityException or UnauthorizedAccessException)
+        {
+            // A leftover key is no reason to fail a test that passed
+        }
+    }
+}