Add ComScope disposal test

Add a test to ensure ComScope is "null" after disposal.

src/thirtytwo/Win32/System/Registry/Registry.cs

@@ -41,24 +41,21 @@ public static string QueryKeyName(HKEY key)
         }
 
         using BufferScope<char> buffer = new(stackalloc char[256]);
-        while (true)
+        while (true) fixed (char* b = buffer)
         {
-            fixed (char* b = buffer)
-            {
-                uint length;
-                NTSTATUS status = Wdk.Interop.NtQueryKey(key, KEY_INFORMATION_CLASS.KeyNameInformation, b, (uint)buffer.Length, &length);
+            uint length;
+            NTSTATUS status = Wdk.Interop.NtQueryKey(key, KEY_INFORMATION_CLASS.KeyNameInformation, b, (uint)buffer.Length, &length);
 
-                if (status == NTSTATUS.STATUS_BUFFER_TOO_SMALL || status == NTSTATUS.STATUS_BUFFER_OVERFLOW)
-                {
-                    buffer.EnsureCapacity((int)length);
-                    continue;
-                }
+            if (status == NTSTATUS.STATUS_BUFFER_TOO_SMALL || status == NTSTATUS.STATUS_BUFFER_OVERFLOW)
+            {
+                buffer.EnsureCapacity((int)length);
+                continue;
+            }
 
-                status.ThrowIfFailed();
+            status.ThrowIfFailed();
 
-                KEY_NAME_INFORMATION* nameInfo = (KEY_NAME_INFORMATION*)b;
-                return new ReadOnlySpan<char>(nameInfo->Name.Value, (int)nameInfo->NameLength / sizeof(char)).ToString();
-            }
+            KEY_NAME_INFORMATION* nameInfo = (KEY_NAME_INFORMATION*)b;
+            return new ReadOnlySpan<char>(nameInfo->Name.Value, (int)nameInfo->NameLength / sizeof(char)).ToString();
         }
     }
 

src/thirtytwo_tests/Win32/System/Com/ComScopeTests.cs

@@ -0,0 +1,62 @@
+// Copyright (c) Jeremy W. Kuhne. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using Windows.Win32.Foundation;
+
+namespace Windows.Win32.System.Com;
+
+public unsafe class ComScopeTests
+{
+    [StaFact]
+    public void ComScope_NullAfterDispose()
+    {
+        ComScope<ITestObject> scope = new(ComHelpers.GetComPointer<ITestObject>(new TestObject()));
+        scope.IsNull.Should().BeFalse();
+        scope.Dispose();
+        scope.IsNull.Should().BeTrue();
+    }
+
+    public class TestObject : ITestObject.Interface, IManagedWrapper<ITestObject>
+    {
+    }
+
+    public readonly unsafe struct ITestObject : IComIID, IVTable<ITestObject, ITestObject.Vtbl>
+    {
+        private readonly void** _vtbl;
+
+        public struct Vtbl
+        {
+            internal delegate* unmanaged[Stdcall]<ITestObject*, Guid*, void**, HRESULT> QueryInterface_1;
+            internal delegate* unmanaged[Stdcall]<ITestObject*, uint> AddRef_2;
+            internal delegate* unmanaged[Stdcall]<ITestObject*, uint> Release_3;
+        }
+
+        [ComImport]
+        [Guid("630A7370-733D-43E9-8141-685DAE2BDB44")]
+        [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+        public interface Interface
+        {
+        }
+
+        static ref readonly Guid IComIID.Guid
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get
+            {
+                ReadOnlySpan<byte> data = new byte[]
+                {
+                    // "3BE9EE32-26FB-4E7A-B8A8-25795A7EFB53"
+                    0x70, 0x73, 0x0A, 0x63, 0x3D, 0x73, 0xE9, 0x43, 0x81, 0x41, 0x68, 0x5D, 0xAE, 0x2B, 0xDB, 0x44
+                };
+
+                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
+            }
+        }
+
+        static void IVTable<ITestObject, Vtbl>.PopulateVTable(Vtbl* vtable)
+        {
+        }
+    }
+}