Expand framework support and COM ABI coverage

Target .NET 8, 9, 10, Framework 4.7.2, and Framework 4.8. Rename samples to stable Core and Framework names. Add raw-vtable COM tests for x64, x86, and ARM64, and require the Azure architecture matrix before packaging.
2026-08-28 11:22:53 +10:00
parent be65cbaa93
commit 43af44f87f
52 changed files with 1116 additions and 128 deletions
@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [ComVisible(true)]
+    [ClassInterface(ClassInterfaceType.None)]
+    [Guid("2A83F3F8-A46C-4104-8FFB-BD9979279450")]
+    internal sealed class AbiTestCredentialProvider : CredentialProviderBase
+    {
+        public AbiTestCredentialProvider()
+        {
+            this.Field = new SmallLabelControl("message", "COM ABI test");
+        }
+
+        public SmallLabelControl Field { get; }
+
+        public AbiTestCredentialTile2 Tile { get; private set; }
+
+        public override bool IsUsageScenarioSupported(UsageScenario cpus, CredUIWinFlags dwFlags)
+        {
+            return cpus == UsageScenario.CredUI;
+        }
+
+        public override IEnumerable<ControlBase> GetControls(UsageScenario cpus)
+        {
+            return new ControlBase[] { this.Field };
+        }
+
+        public override bool ShouldIncludeUserTile(CredentialProviderUser user)
+        {
+            return false;
+        }
+
+        public override bool ShouldIncludeGenericTile()
+        {
+            return true;
+        }
+
+        public override CredentialTile CreateGenericTile()
+        {
+            this.Tile = new AbiTestCredentialTile2(this);
+            return this.Tile;
+        }
+
+        public override CredentialTile2 CreateUserTile(CredentialProviderUser user)
+        {
+            return null;
+        }
+    }
+}
@@ -0,0 +1,14 @@
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    internal sealed class AbiTestCredentialTile2 : CredentialTile2
+    {
+        public AbiTestCredentialTile2(CredentialProviderBase credentialProvider) : base(credentialProvider)
+        {
+        }
+
+        protected override CredentialResponseBase GetCredentials()
+        {
+            return null;
+        }
+    }
+}
@@ -0,0 +1,79 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    internal sealed class ComInterfacePointer : IDisposable
+    {
+        private IntPtr value;
+
+        private ComInterfacePointer(IntPtr value)
+        {
+            this.value = value;
+        }
+
+        public IntPtr Value
+        {
+            get
+            {
+                if (this.value == IntPtr.Zero)
+                {
+                    throw new ObjectDisposedException(nameof(ComInterfacePointer));
+                }
+
+                return this.value;
+            }
+        }
+
+        public static ComInterfacePointer Create(object instance, Guid interfaceId)
+        {
+            IntPtr unknown = Marshal.GetIUnknownForObject(instance);
+
+            try
+            {
+                int hresult = ComMarshal.QueryInterface(unknown, interfaceId, out IntPtr interfacePointer);
+                if (hresult != CredentialProviderAbi.S_OK)
+                {
+                    if (interfacePointer != IntPtr.Zero)
+                    {
+                        Marshal.Release(interfacePointer);
+                    }
+
+                    throw new COMException("The COM interface was not available", hresult);
+                }
+
+                return new ComInterfacePointer(interfacePointer);
+            }
+            finally
+            {
+                Marshal.Release(unknown);
+            }
+        }
+
+        public static ComInterfacePointer TakeOwnership(IntPtr value)
+        {
+            if (value == IntPtr.Zero)
+            {
+                throw new ArgumentException("The COM interface pointer cannot be zero", nameof(value));
+            }
+
+            return new ComInterfacePointer(value);
+        }
+
+        public TDelegate GetMethod<TDelegate>(int slot) where TDelegate : class
+        {
+            IntPtr vtable = Marshal.ReadIntPtr(this.Value);
+            IntPtr method = Marshal.ReadIntPtr(vtable, checked(slot * IntPtr.Size));
+            return (TDelegate)(object)Marshal.GetDelegateForFunctionPointer(method, typeof(TDelegate));
+        }
+
+        public void Dispose()
+        {
+            if (this.value != IntPtr.Zero)
+            {
+                Marshal.Release(this.value);
+                this.value = IntPtr.Zero;
+            }
+        }
+    }
+}
@@ -0,0 +1,17 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    internal static class ComMarshal
+    {
+        public static int QueryInterface(IntPtr unknown, Guid interfaceId, out IntPtr interfacePointer)
+        {
+#if NET9_0_OR_GREATER
+            return Marshal.QueryInterface(unknown, in interfaceId, out interfacePointer);
+#else
+            return Marshal.QueryInterface(unknown, ref interfaceId, out interfacePointer);
+#endif
+        }
+    }
+}
@@ -0,0 +1,59 @@
+using System;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    internal static class CredentialProviderAbi
+    {
+        public static readonly Guid ICredentialProvider = new Guid("D27C3481-5A1C-45B2-8AAA-C20EBBE8229E");
+
+        public static readonly Guid ICredentialProviderCredential = new Guid("63913A93-40C1-481A-818D-4072FF8C70CC");
+
+        public static readonly Guid ICredentialProviderCredential2 = new Guid("FD672C54-40EA-4D6E-9B49-CFB1A7507BD7");
+
+        public static readonly Guid ICredentialProviderSetUserArray = new Guid("095C1484-1C0C-4388-9C6D-500E61BF84BD");
+
+        public static readonly Guid ICredentialProviderUserArray = new Guid("90C119AE-0F18-4520-A1F1-114366A40FE8");
+
+        public const int SetUsageScenarioSlot = 3;
+
+        public const int GetFieldDescriptorCountSlot = 7;
+
+        public const int GetFieldDescriptorAtSlot = 8;
+
+        public const int GetCredentialCountSlot = 9;
+
+        public const int GetCredentialAtSlot = 10;
+
+        public const int SetUserArraySlot = 3;
+
+        public const int UserArrayGetCountSlot = 5;
+
+        public const int SetSelectedSlot = 5;
+
+        public const int SetDeselectedSlot = 6;
+
+        public const int GetFieldStateSlot = 7;
+
+        public const int GetStringValueSlot = 8;
+
+        public const int GetUserSidSlot = 20;
+
+        public const int SmallTextFieldType = 2;
+
+        public const int DisplayInSelectedTileFieldState = 1;
+
+        public const int NoInteractiveFieldState = 0;
+
+        public const uint NoDefaultCredential = 0xFFFFFFFF;
+
+        public const int S_OK = 0;
+
+        public const int S_FALSE = 1;
+
+        public const int E_FAIL = unchecked((int)0x80004005);
+
+        public const int E_INVALIDARG = unchecked((int)0x80070057);
+
+        public const int E_NOTIMPL = unchecked((int)0x80004001);
+    }
+}
@@ -0,0 +1,450 @@
+using System;
+using System.Runtime.InteropServices;
+using System.Threading;
+using NUnit.Framework;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [TestFixture]
+    [NonParallelizable]
+    [Apartment(ApartmentState.STA)]
+    public class CredentialProviderAbiTests
+    {
+        [Test]
+        public void CredentialProviderInterfaceCanBeQueried()
+        {
+            var provider = new AbiTestCredentialProvider();
+            IntPtr unknown = Marshal.GetIUnknownForObject(provider);
+            IntPtr providerInterface = IntPtr.Zero;
+
+            try
+            {
+                int hresult = ComMarshal.QueryInterface(unknown, CredentialProviderAbi.ICredentialProvider, out providerInterface);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                Assert.That(providerInterface, Is.Not.EqualTo(IntPtr.Zero));
+            }
+            finally
+            {
+                if (providerInterface != IntPtr.Zero)
+                {
+                    Marshal.Release(providerInterface);
+                }
+
+                Marshal.Release(unknown);
+                GC.KeepAlive(provider);
+            }
+        }
+
+        [Test]
+        public void SetUsageScenarioPreservesHResultAndArguments()
+        {
+            var provider = new AbiTestCredentialProvider();
+
+            using (ComInterfacePointer providerInterface = ComInterfacePointer.Create(provider, CredentialProviderAbi.ICredentialProvider))
+            {
+                SetUsageScenarioDelegate setUsageScenario = providerInterface.GetMethod<SetUsageScenarioDelegate>(CredentialProviderAbi.SetUsageScenarioSlot);
+
+                int hresult = setUsageScenario(providerInterface.Value, (int)UsageScenario.CredUI, (uint)CredUIWinFlags.CREDUIWIN_SECURE_PROMPT);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                Assert.That(provider.UsageScenario, Is.EqualTo(UsageScenario.CredUI));
+                Assert.That(provider.CredUIFlags, Is.EqualTo(CredUIWinFlags.CREDUIWIN_SECURE_PROMPT));
+
+                hresult = setUsageScenario(providerInterface.Value, (int)UsageScenario.Logon, 0);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.E_NOTIMPL));
+                Assert.That(provider.UsageScenario, Is.EqualTo(UsageScenario.Logon));
+                Assert.That(provider.CredUIFlags, Is.EqualTo((CredUIWinFlags)0));
+            }
+
+            GC.KeepAlive(provider);
+        }
+
+        [Test]
+        public void GetFieldDescriptorCountReturnsProviderControlCount()
+        {
+            var provider = new AbiTestCredentialProvider();
+
+            using (ComInterfacePointer providerInterface = ComInterfacePointer.Create(provider, CredentialProviderAbi.ICredentialProvider))
+            {
+                GetFieldDescriptorCountDelegate getFieldDescriptorCount = providerInterface.GetMethod<GetFieldDescriptorCountDelegate>(CredentialProviderAbi.GetFieldDescriptorCountSlot);
+
+                int hresult = getFieldDescriptorCount(providerInterface.Value, out uint count);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                Assert.That(count, Is.EqualTo(1));
+            }
+
+            GC.KeepAlive(provider);
+        }
+
+        [Test]
+        public void GetFieldDescriptorAtReturnsWindowsSdkLayout()
+        {
+            var provider = new AbiTestCredentialProvider();
+
+            using (ComInterfacePointer providerInterface = ComInterfacePointer.Create(provider, CredentialProviderAbi.ICredentialProvider))
+            {
+                GetFieldDescriptorCountDelegate getFieldDescriptorCount = providerInterface.GetMethod<GetFieldDescriptorCountDelegate>(CredentialProviderAbi.GetFieldDescriptorCountSlot);
+                GetFieldDescriptorAtDelegate getFieldDescriptorAt = providerInterface.GetMethod<GetFieldDescriptorAtDelegate>(CredentialProviderAbi.GetFieldDescriptorAtSlot);
+
+                Assert.That(getFieldDescriptorCount(providerInterface.Value, out uint count), Is.EqualTo(CredentialProviderAbi.S_OK));
+                Assert.That(count, Is.EqualTo(1));
+
+                IntPtr descriptorPointer = IntPtr.Zero;
+                IntPtr labelPointer = IntPtr.Zero;
+
+                try
+                {
+                    int hresult = getFieldDescriptorAt(providerInterface.Value, 0, out descriptorPointer);
+
+                    Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                    Assert.That(descriptorPointer, Is.Not.EqualTo(IntPtr.Zero));
+
+                    NativeCredentialProviderFieldDescriptor descriptor = Marshal.PtrToStructure<NativeCredentialProviderFieldDescriptor>(descriptorPointer);
+                    labelPointer = descriptor.Label;
+
+                    Assert.That(descriptor.FieldId, Is.EqualTo(provider.Field.Id));
+                    Assert.That(descriptor.FieldType, Is.EqualTo(CredentialProviderAbi.SmallTextFieldType));
+                    Assert.That(Marshal.PtrToStringUni(labelPointer), Is.EqualTo("COM ABI test"));
+                    Assert.That(descriptor.FieldTypeGuid, Is.EqualTo(Guid.Empty));
+                }
+                finally
+                {
+                    if (labelPointer != IntPtr.Zero)
+                    {
+                        Marshal.FreeCoTaskMem(labelPointer);
+                    }
+
+                    if (descriptorPointer != IntPtr.Zero)
+                    {
+                        Marshal.FreeCoTaskMem(descriptorPointer);
+                    }
+                }
+            }
+
+            GC.KeepAlive(provider);
+        }
+
+        [Test]
+        public void GetFieldDescriptorAtRejectsInvalidIndex()
+        {
+            var provider = new AbiTestCredentialProvider();
+
+            using (ComInterfacePointer providerInterface = ComInterfacePointer.Create(provider, CredentialProviderAbi.ICredentialProvider))
+            {
+                GetFieldDescriptorCountDelegate getFieldDescriptorCount = providerInterface.GetMethod<GetFieldDescriptorCountDelegate>(CredentialProviderAbi.GetFieldDescriptorCountSlot);
+                GetFieldDescriptorAtDelegate getFieldDescriptorAt = providerInterface.GetMethod<GetFieldDescriptorAtDelegate>(CredentialProviderAbi.GetFieldDescriptorAtSlot);
+
+                Assert.That(getFieldDescriptorCount(providerInterface.Value, out uint count), Is.EqualTo(CredentialProviderAbi.S_OK));
+                Assert.That(count, Is.EqualTo(1));
+
+                int hresult = getFieldDescriptorAt(providerInterface.Value, count, out IntPtr descriptorPointer);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.E_INVALIDARG));
+                Assert.That(descriptorPointer, Is.EqualTo(IntPtr.Zero));
+            }
+
+            GC.KeepAlive(provider);
+        }
+
+        [Test]
+        public void CredentialProviderSetUserArrayInterfaceCanBeQueried()
+        {
+            var provider = new AbiTestCredentialProvider();
+            IntPtr unknown = Marshal.GetIUnknownForObject(provider);
+            IntPtr setUserArrayInterface = IntPtr.Zero;
+
+            try
+            {
+                int hresult = ComMarshal.QueryInterface(unknown, CredentialProviderAbi.ICredentialProviderSetUserArray, out setUserArrayInterface);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                Assert.That(setUserArrayInterface, Is.Not.EqualTo(IntPtr.Zero));
+            }
+            finally
+            {
+                if (setUserArrayInterface != IntPtr.Zero)
+                {
+                    Marshal.Release(setUserArrayInterface);
+                }
+
+                Marshal.Release(unknown);
+                GC.KeepAlive(provider);
+            }
+        }
+
+        [Test]
+        public void TestUserArrayUsesWindowsSdkGetCountSlot()
+        {
+            var users = new TestCredentialProviderUserArray();
+
+            using (ComInterfacePointer userArrayInterface = ComInterfacePointer.Create(users, CredentialProviderAbi.ICredentialProviderUserArray))
+            {
+                GetUserCountDelegate getCount = userArrayInterface.GetMethod<GetUserCountDelegate>(CredentialProviderAbi.UserArrayGetCountSlot);
+
+                int hresult = getCount(userArrayInterface.Value, out uint count);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                Assert.That(count, Is.EqualTo(0));
+                Assert.That(users.GetCountCallCount, Is.EqualTo(1));
+            }
+
+            GC.KeepAlive(users);
+        }
+
+        [Test]
+        public void SetUserArrayInvokesWindowsSdkUserArrayGetCount()
+        {
+            var provider = new AbiTestCredentialProvider();
+            var users = new TestCredentialProviderUserArray();
+
+            SetEmptyUserArray(provider, users);
+
+            Assert.That(users.GetCountCallCount, Is.EqualTo(1));
+
+            GC.KeepAlive(users);
+            GC.KeepAlive(provider);
+        }
+
+        [Test]
+        public void GetCredentialCountReturnsGenericTileWithoutDefault()
+        {
+            var provider = new AbiTestCredentialProvider();
+            var users = new TestCredentialProviderUserArray();
+
+            SetEmptyUserArray(provider, users);
+
+            using (ComInterfacePointer providerInterface = ComInterfacePointer.Create(provider, CredentialProviderAbi.ICredentialProvider))
+            {
+                GetCredentialCountDelegate getCredentialCount = providerInterface.GetMethod<GetCredentialCountDelegate>(CredentialProviderAbi.GetCredentialCountSlot);
+
+                int hresult = getCredentialCount(providerInterface.Value, out uint count, out uint defaultCredential, out int autoLogonWithDefault);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                Assert.That(count, Is.EqualTo(1));
+                Assert.That(defaultCredential, Is.EqualTo(CredentialProviderAbi.NoDefaultCredential));
+                Assert.That(autoLogonWithDefault, Is.EqualTo(0));
+                Assert.That(users.GetCountCallCount, Is.EqualTo(2));
+                Assert.That(provider.Tile, Is.Not.Null);
+            }
+
+            GC.KeepAlive(users);
+            GC.KeepAlive(provider);
+        }
+
+        [Test]
+        public void GetCredentialAtRejectsInvalidIndex()
+        {
+            var provider = new AbiTestCredentialProvider();
+            var users = new TestCredentialProviderUserArray();
+
+            SetEmptyUserArray(provider, users);
+
+            using (ComInterfacePointer providerInterface = ComInterfacePointer.Create(provider, CredentialProviderAbi.ICredentialProvider))
+            {
+                GetCredentialCountDelegate getCredentialCount = providerInterface.GetMethod<GetCredentialCountDelegate>(CredentialProviderAbi.GetCredentialCountSlot);
+                GetCredentialAtDelegate getCredentialAt = providerInterface.GetMethod<GetCredentialAtDelegate>(CredentialProviderAbi.GetCredentialAtSlot);
+
+                Assert.That(getCredentialCount(providerInterface.Value, out uint count, out uint defaultCredential, out int autoLogonWithDefault), Is.EqualTo(CredentialProviderAbi.S_OK));
+
+                int hresult = getCredentialAt(providerInterface.Value, count, out IntPtr credential);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.E_FAIL));
+                Assert.That(credential, Is.EqualTo(IntPtr.Zero));
+            }
+
+            GC.KeepAlive(users);
+            GC.KeepAlive(provider);
+        }
+
+        [Test]
+        public void CredentialV1SelectionMethodsPreserveStateAndHResults()
+        {
+            var provider = new AbiTestCredentialProvider();
+            var users = new TestCredentialProviderUserArray();
+
+            using (ComInterfacePointer credential = CreateCredentialInterface(provider, users))
+            {
+                SetSelectedDelegate setSelected = credential.GetMethod<SetSelectedDelegate>(CredentialProviderAbi.SetSelectedSlot);
+                SetDeselectedDelegate setDeselected = credential.GetMethod<SetDeselectedDelegate>(CredentialProviderAbi.SetDeselectedSlot);
+
+                int hresult = setSelected(credential.Value, out int autoLogon);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                Assert.That(autoLogon, Is.EqualTo(0));
+                Assert.That(provider.Tile.IsSelected, Is.True);
+
+                hresult = setDeselected(credential.Value);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                Assert.That(provider.Tile.IsSelected, Is.False);
+            }
+
+            GC.KeepAlive(users);
+            GC.KeepAlive(provider);
+        }
+
+        [Test]
+        public void CredentialV1GetFieldStateUsesWindowsSdkEnumValues()
+        {
+            var provider = new AbiTestCredentialProvider();
+            var users = new TestCredentialProviderUserArray();
+
+            using (ComInterfacePointer credential = CreateCredentialInterface(provider, users))
+            {
+                GetFieldStateDelegate getFieldState = credential.GetMethod<GetFieldStateDelegate>(CredentialProviderAbi.GetFieldStateSlot);
+
+                int hresult = getFieldState(credential.Value, provider.Field.Id, out int fieldState, out int interactiveState);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                Assert.That(fieldState, Is.EqualTo(CredentialProviderAbi.DisplayInSelectedTileFieldState));
+                Assert.That(interactiveState, Is.EqualTo(CredentialProviderAbi.NoInteractiveFieldState));
+            }
+
+            GC.KeepAlive(users);
+            GC.KeepAlive(provider);
+        }
+
+        [Test]
+        public void CredentialV1GetStringValueReturnsComTaskMemory()
+        {
+            var provider = new AbiTestCredentialProvider();
+            var users = new TestCredentialProviderUserArray();
+
+            using (ComInterfacePointer credential = CreateCredentialInterface(provider, users))
+            {
+                GetStringValueDelegate getStringValue = credential.GetMethod<GetStringValueDelegate>(CredentialProviderAbi.GetStringValueSlot);
+                IntPtr value = IntPtr.Zero;
+
+                try
+                {
+                    int hresult = getStringValue(credential.Value, provider.Field.Id, out value);
+
+                    Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                    Assert.That(value, Is.Not.EqualTo(IntPtr.Zero));
+                    Assert.That(Marshal.PtrToStringUni(value), Is.EqualTo("COM ABI test"));
+                }
+                finally
+                {
+                    if (value != IntPtr.Zero)
+                    {
+                        Marshal.FreeCoTaskMem(value);
+                    }
+                }
+            }
+
+            GC.KeepAlive(users);
+            GC.KeepAlive(provider);
+        }
+
+        [Test]
+        public void CredentialV2GetUserSidUsesInheritedVtableOrder()
+        {
+            var provider = new AbiTestCredentialProvider();
+            var users = new TestCredentialProviderUserArray();
+
+            using (ComInterfacePointer credential = CreateCredentialInterface(provider, users))
+            {
+                IntPtr credential2Pointer = IntPtr.Zero;
+
+                try
+                {
+                    int hresult = ComMarshal.QueryInterface(credential.Value, CredentialProviderAbi.ICredentialProviderCredential2, out credential2Pointer);
+
+                    Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                    Assert.That(credential2Pointer, Is.Not.EqualTo(IntPtr.Zero));
+
+                    using (ComInterfacePointer credential2 = ComInterfacePointer.TakeOwnership(credential2Pointer))
+                    {
+                        credential2Pointer = IntPtr.Zero;
+                        GetUserSidDelegate getUserSid = credential2.GetMethod<GetUserSidDelegate>(CredentialProviderAbi.GetUserSidSlot);
+                        IntPtr sid = IntPtr.Zero;
+
+                        try
+                        {
+                            hresult = getUserSid(credential2.Value, out sid);
+
+                            Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_FALSE));
+                            Assert.That(sid, Is.EqualTo(IntPtr.Zero));
+                        }
+                        finally
+                        {
+                            if (sid != IntPtr.Zero)
+                            {
+                                Marshal.FreeCoTaskMem(sid);
+                            }
+                        }
+                    }
+                }
+                finally
+                {
+                    if (credential2Pointer != IntPtr.Zero)
+                    {
+                        Marshal.Release(credential2Pointer);
+                    }
+                }
+            }
+
+            GC.KeepAlive(users);
+            GC.KeepAlive(provider);
+        }
+
+        [Test]
+        public void FieldDescriptorDeclarationMatchesWindowsSdkSize()
+        {
+            int expectedSize = IntPtr.Size == 4 ? 28 : 32;
+
+            Assert.That(Marshal.SizeOf<NativeCredentialProviderFieldDescriptor>(), Is.EqualTo(expectedSize));
+        }
+
+        private static void SetEmptyUserArray(AbiTestCredentialProvider provider, TestCredentialProviderUserArray users)
+        {
+            using (ComInterfacePointer setUserArrayInterface = ComInterfacePointer.Create(provider, CredentialProviderAbi.ICredentialProviderSetUserArray))
+            using (ComInterfacePointer userArrayInterface = ComInterfacePointer.Create(users, CredentialProviderAbi.ICredentialProviderUserArray))
+            {
+                SetUserArrayDelegate setUserArray = setUserArrayInterface.GetMethod<SetUserArrayDelegate>(CredentialProviderAbi.SetUserArraySlot);
+
+                int hresult = setUserArray(setUserArrayInterface.Value, userArrayInterface.Value);
+
+                Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+            }
+        }
+
+        private static ComInterfacePointer CreateCredentialInterface(AbiTestCredentialProvider provider, TestCredentialProviderUserArray users)
+        {
+            SetEmptyUserArray(provider, users);
+
+            using (ComInterfacePointer providerInterface = ComInterfacePointer.Create(provider, CredentialProviderAbi.ICredentialProvider))
+            {
+                GetCredentialCountDelegate getCredentialCount = providerInterface.GetMethod<GetCredentialCountDelegate>(CredentialProviderAbi.GetCredentialCountSlot);
+                GetCredentialAtDelegate getCredentialAt = providerInterface.GetMethod<GetCredentialAtDelegate>(CredentialProviderAbi.GetCredentialAtSlot);
+
+                Assert.That(getCredentialCount(providerInterface.Value, out uint count, out uint defaultCredential, out int autoLogonWithDefault), Is.EqualTo(CredentialProviderAbi.S_OK));
+                Assert.That(count, Is.EqualTo(1));
+
+                IntPtr credential = IntPtr.Zero;
+
+                try
+                {
+                    int hresult = getCredentialAt(providerInterface.Value, 0, out credential);
+
+                    Assert.That(hresult, Is.EqualTo(CredentialProviderAbi.S_OK));
+                    Assert.That(credential, Is.Not.EqualTo(IntPtr.Zero));
+
+                    ComInterfacePointer result = ComInterfacePointer.TakeOwnership(credential);
+                    credential = IntPtr.Zero;
+                    return result;
+                }
+                finally
+                {
+                    if (credential != IntPtr.Zero)
+                    {
+                        Marshal.Release(credential);
+                    }
+                }
+            }
+        }
+    }
+}
@@ -0,0 +1,8 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    internal delegate int GetCredentialAtDelegate(IntPtr instance, uint index, out IntPtr credential);
+}
@@ -0,0 +1,8 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    internal delegate int GetCredentialCountDelegate(IntPtr instance, out uint count, out uint defaultCredential, out int autoLogonWithDefault);
+}
@@ -0,0 +1,8 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    internal delegate int GetFieldDescriptorAtDelegate(IntPtr instance, uint index, out IntPtr descriptor);
+}
@@ -0,0 +1,8 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    internal delegate int GetFieldDescriptorCountDelegate(IntPtr instance, out uint count);
+}
@@ -0,0 +1,8 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    internal delegate int GetFieldStateDelegate(IntPtr instance, uint fieldId, out int fieldState, out int interactiveState);
+}
@@ -0,0 +1,8 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    internal delegate int GetStringValueDelegate(IntPtr instance, uint fieldId, out IntPtr value);
+}
@@ -0,0 +1,8 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    internal delegate int GetUserCountDelegate(IntPtr instance, out uint count);
+}
@@ -0,0 +1,8 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    internal delegate int GetUserSidDelegate(IntPtr instance, out IntPtr sid);
+}
@@ -0,0 +1,27 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [ComVisible(true)]
+    [Guid("90C119AE-0F18-4520-A1F1-114366A40FE8")]
+    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+    public interface ITestCredentialProviderUserArray
+    {
+        [PreserveSig]
+        [return: MarshalAs(UnmanagedType.Error)]
+        int SetProviderFilter(ref Guid providerToFilterTo);
+
+        [PreserveSig]
+        [return: MarshalAs(UnmanagedType.Error)]
+        int GetAccountOptions(out int accountOptions);
+
+        [PreserveSig]
+        [return: MarshalAs(UnmanagedType.Error)]
+        int GetCount(out uint userCount);
+
+        [PreserveSig]
+        [return: MarshalAs(UnmanagedType.Error)]
+        int GetAt(uint userIndex, out IntPtr user);
+    }
+}
@@ -0,0 +1,17 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [StructLayout(LayoutKind.Sequential)]
+    internal struct NativeCredentialProviderFieldDescriptor
+    {
+        public uint FieldId;
+
+        public int FieldType;
+
+        public IntPtr Label;
+
+        public Guid FieldTypeGuid;
+    }
+}
@@ -0,0 +1,27 @@
+using System;
+using NUnit.Framework;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [TestFixture]
+    public class ProcessArchitectureTests
+    {
+        [Test]
+        public void TestHostUsesRequestedArchitecture()
+        {
+#if TEST_X86
+            const string expectedArchitecture = "x86";
+#elif TEST_X64
+            const string expectedArchitecture = "AMD64";
+#elif TEST_ARM64
+            const string expectedArchitecture = "ARM64";
+#else
+#error A test process architecture must be defined by the project.
+#endif
+
+            string actualArchitecture = Environment.GetEnvironmentVariable("PROCESSOR_ARCHITECTURE");
+
+            Assert.That(actualArchitecture, Is.EqualTo(expectedArchitecture).IgnoreCase);
+        }
+    }
+}
@@ -0,0 +1,8 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    internal delegate int SetDeselectedDelegate(IntPtr instance);
+}
@@ -0,0 +1,8 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    internal delegate int SetSelectedDelegate(IntPtr instance, out int autoLogon);
+}
@@ -0,0 +1,8 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    internal delegate int SetUsageScenarioDelegate(IntPtr instance, int usageScenario, uint flags);
+}
@@ -0,0 +1,8 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    internal delegate int SetUserArrayDelegate(IntPtr instance, IntPtr users);
+}
@@ -0,0 +1,51 @@
+using System;
+using System.Runtime.InteropServices;
+using Lithnet.CredentialProvider.Interop;
+
+namespace Lithnet.CredentialProvider.UnitTests.ComInterop
+{
+    [ComVisible(true)]
+    [ClassInterface(ClassInterfaceType.None)]
+    // The in-process call also requires the callback to implement the parameter's managed interface type.
+    // ITestCredentialProviderUserArray keeps the COM contract under test independent of that adapter.
+    internal sealed class TestCredentialProviderUserArray : ITestCredentialProviderUserArray, ICredentialProviderUserArray
+    {
+        public int GetCountCallCount { get; private set; }
+
+        public int SetProviderFilter(ref Guid providerToFilterTo)
+        {
+            return CredentialProviderAbi.E_NOTIMPL;
+        }
+
+        public int GetAccountOptions(out int accountOptions)
+        {
+            accountOptions = 0;
+            return CredentialProviderAbi.S_OK;
+        }
+
+        public int GetCount(out uint userCount)
+        {
+            this.GetCountCallCount++;
+            userCount = 0;
+            return CredentialProviderAbi.S_OK;
+        }
+
+        public int GetAt(uint userIndex, out IntPtr user)
+        {
+            user = IntPtr.Zero;
+            return CredentialProviderAbi.E_INVALIDARG;
+        }
+
+        int ICredentialProviderUserArray.GetAccountOptions(out AccountOptions accountOptions)
+        {
+            accountOptions = AccountOptions.None;
+            return CredentialProviderAbi.S_OK;
+        }
+
+        int ICredentialProviderUserArray.GetAt(uint userIndex, out ICredentialProviderUser user)
+        {
+            user = null;
+            return CredentialProviderAbi.E_INVALIDARG;
+        }
+    }
+}