diff --git a/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatefulCollectionPinnableReference.cs b/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatefulCollectionPinnableReference.cs
new file mode 100644
index 00000000000000..f417e7bc314cca
--- /dev/null
+++ b/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatefulCollectionPinnableReference.cs
@@ -0,0 +1,86 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Runtime.InteropServices;
+using System.Runtime.InteropServices.Marshalling;
+
+namespace SharedTypes.ComInterfaces
+{
+    [GeneratedComInterface(), Guid("0A52BA7C-E08B-42A4-A1F4-1A2BF2C07E60")]
+    internal partial interface IStatefulCollectionPinnableReference
+    {
+        void Method(
+            [MarshalUsing(CountElementName = nameof(size))] StatefulCollectionPinnableReference<int> p,
+            int size);
+
+        void MethodIn(
+            [MarshalUsing(CountElementName = nameof(size))] in StatefulCollectionPinnableReference<int> pIn,
+            in int size);
+
+        void MethodRef(
+            [MarshalUsing(CountElementName = nameof(size))] ref StatefulCollectionPinnableReference<int> pRef,
+            int size);
+
+        void MethodOut(
+            [MarshalUsing(CountElementName = nameof(size))] out StatefulCollectionPinnableReference<int> pOut,
+            out int size);
+
+        [return: MarshalUsing(CountElementName = nameof(size))]
+        StatefulCollectionPinnableReference<int> Return(int size);
+    }
+
+    [NativeMarshalling(typeof(StatefulCollectionPinnableReferenceMarshaller<,>))]
+    internal class StatefulCollectionPinnableReference<T>
+    {
+    }
+
+    internal struct StatefulCollectionPinnableReferenceNative
+    {
+        public static unsafe explicit operator void*(StatefulCollectionPinnableReferenceNative _) => throw new NotImplementedException();
+        public static unsafe explicit operator StatefulCollectionPinnableReferenceNative(void* _) => throw new NotImplementedException();
+    }
+
+    [ContiguousCollectionMarshaller]
+    [CustomMarshaller(typeof(StatefulCollectionPinnableReference<>), MarshalMode.ManagedToUnmanagedRef, typeof(StatefulCollectionPinnableReferenceMarshaller<,>.Bidirectional))]
+    [CustomMarshaller(typeof(StatefulCollectionPinnableReference<>), MarshalMode.UnmanagedToManagedRef, typeof(StatefulCollectionPinnableReferenceMarshaller<,>.Bidirectional))]
+    [CustomMarshaller(typeof(StatefulCollectionPinnableReference<>), MarshalMode.ManagedToUnmanagedOut, typeof(StatefulCollectionPinnableReferenceMarshaller<,>.UnmanagedToManaged))]
+    [CustomMarshaller(typeof(StatefulCollectionPinnableReference<>), MarshalMode.UnmanagedToManagedIn, typeof(StatefulCollectionPinnableReferenceMarshaller<,>.UnmanagedToManaged))]
+    [CustomMarshaller(typeof(StatefulCollectionPinnableReference<>), MarshalMode.ManagedToUnmanagedIn, typeof(StatefulCollectionPinnableReferenceMarshaller<,>.ManagedToUnmanaged))]
+    [CustomMarshaller(typeof(StatefulCollectionPinnableReference<>), MarshalMode.UnmanagedToManagedOut, typeof(StatefulCollectionPinnableReferenceMarshaller<,>.ManagedToUnmanaged))]
+    internal static class StatefulCollectionPinnableReferenceMarshaller<T, TUnmanaged> where TUnmanaged : unmanaged
+    {
+        public struct Bidirectional
+        {
+            public void FromManaged(StatefulCollectionPinnableReference<T> managed) => throw new NotImplementedException();
+            public StatefulCollectionPinnableReferenceNative ToUnmanaged() => throw new NotImplementedException();
+            public ReadOnlySpan<T> GetManagedValuesSource() => throw new NotImplementedException();
+            public Span<TUnmanaged> GetUnmanagedValuesDestination() => throw new NotImplementedException();
+
+            public void FromUnmanaged(StatefulCollectionPinnableReferenceNative unmanaged) => throw new NotImplementedException();
+            public StatefulCollectionPinnableReference<T> ToManaged() => throw new NotImplementedException();
+            public ReadOnlySpan<TUnmanaged> GetUnmanagedValuesSource(int numElements) => throw new NotImplementedException();
+            public Span<T> GetManagedValuesDestination(int numElements) => throw new NotImplementedException();
+
+            public void Free() => throw new NotImplementedException();
+        }
+
+        public struct UnmanagedToManaged
+        {
+            public void Free() => throw new NotImplementedException();
+            public void FromUnmanaged(StatefulCollectionPinnableReferenceNative unmanaged) => throw new NotImplementedException();
+            public StatefulCollectionPinnableReference<T> ToManaged() => throw new NotImplementedException();
+            public ReadOnlySpan<TUnmanaged> GetUnmanagedValuesSource(int numElements) => throw new NotImplementedException();
+            public Span<T> GetManagedValuesDestination(int numElements) => throw new NotImplementedException();
+        }
+
+        public struct ManagedToUnmanaged
+        {
+            public void FromManaged(StatefulCollectionPinnableReference<T> managed) => throw new NotImplementedException();
+            public StatefulCollectionPinnableReferenceNative ToUnmanaged() => throw new NotImplementedException();
+            public ReadOnlySpan<T> GetManagedValuesSource() => throw new NotImplementedException();
+            public Span<TUnmanaged> GetUnmanagedValuesDestination() => throw new NotImplementedException();
+            public void Free() => throw new NotImplementedException();
+        }
+    }
+}
diff --git a/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatelessCollectionPinnableReference.cs b/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatelessCollectionPinnableReference.cs
new file mode 100644
index 00000000000000..33d478c597b9c6
--- /dev/null
+++ b/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatelessCollectionPinnableReference.cs
@@ -0,0 +1,85 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Runtime.InteropServices;
+using System.Runtime.InteropServices.Marshalling;
+
+namespace SharedTypes.ComInterfaces
+{
+    [GeneratedComInterface(), Guid("0A52BA7C-E08B-42A4-A1F4-1A2BF2C07E60")]
+    internal partial interface IStatelessCollectionPinnableReference
+    {
+        void Method(
+            [MarshalUsing(CountElementName = nameof(size))] StatelessCollectionPinnableReference<int> p,
+            int size);
+
+        void MethodIn(
+            [MarshalUsing(CountElementName = nameof(size))] in StatelessCollectionPinnableReference<int> pIn,
+            in int size);
+
+        void MethodRef(
+            [MarshalUsing(CountElementName = nameof(size))] ref StatelessCollectionPinnableReference<int> pRef,
+            int size);
+
+        void MethodOut(
+            [MarshalUsing(CountElementName = nameof(size))] out StatelessCollectionPinnableReference<int> pOut,
+            out int size);
+
+        [return: MarshalUsing(CountElementName = nameof(size))]
+        StatelessCollectionPinnableReference<int> Return(int size);
+    }
+
+    [NativeMarshalling(typeof(StatelessCollectionPinnableReferenceMarshaller<,>))]
+    internal class StatelessCollectionPinnableReference<T>
+    {
+    }
+
+    internal struct StatelessCollectionPinnableReferenceNative
+    {
+        public static unsafe explicit operator void*(StatelessCollectionPinnableReferenceNative _) => throw new NotImplementedException();
+        public static unsafe explicit operator StatelessCollectionPinnableReferenceNative(void* _) => throw new NotImplementedException();
+    }
+
+    [ContiguousCollectionMarshaller]
+    [CustomMarshaller(typeof(StatelessCollectionPinnableReference<>), MarshalMode.ManagedToUnmanagedRef, typeof(StatelessCollectionPinnableReferenceMarshaller<,>.Bidirectional))]
+    [CustomMarshaller(typeof(StatelessCollectionPinnableReference<>), MarshalMode.UnmanagedToManagedRef, typeof(StatelessCollectionPinnableReferenceMarshaller<,>.Bidirectional))]
+    [CustomMarshaller(typeof(StatelessCollectionPinnableReference<>), MarshalMode.ElementIn, typeof(StatelessCollectionPinnableReferenceMarshaller<,>.Bidirectional))]
+    [CustomMarshaller(typeof(StatelessCollectionPinnableReference<>), MarshalMode.ElementOut, typeof(StatelessCollectionPinnableReferenceMarshaller<,>.Bidirectional))]
+    [CustomMarshaller(typeof(StatelessCollectionPinnableReference<>), MarshalMode.ElementRef, typeof(StatelessCollectionPinnableReferenceMarshaller<,>.Bidirectional))]
+    [CustomMarshaller(typeof(StatelessCollectionPinnableReference<>), MarshalMode.ManagedToUnmanagedOut, typeof(StatelessCollectionPinnableReferenceMarshaller<,>.UnmanagedToManaged))]
+    [CustomMarshaller(typeof(StatelessCollectionPinnableReference<>), MarshalMode.UnmanagedToManagedIn, typeof(StatelessCollectionPinnableReferenceMarshaller<,>.UnmanagedToManaged))]
+    [CustomMarshaller(typeof(StatelessCollectionPinnableReference<>), MarshalMode.ManagedToUnmanagedIn, typeof(StatelessCollectionPinnableReferenceMarshaller<,>.ManagedToUnmanaged))]
+    [CustomMarshaller(typeof(StatelessCollectionPinnableReference<>), MarshalMode.UnmanagedToManagedOut, typeof(StatelessCollectionPinnableReferenceMarshaller<,>.ManagedToUnmanaged))]
+    internal static class StatelessCollectionPinnableReferenceMarshaller<T, TUnmanaged> where TUnmanaged : unmanaged
+    {
+        public static class Bidirectional
+        {
+            public static ref StatelessCollectionPinnableReferenceNative GetPinnableReference(StatelessCollectionPinnableReference<T> managed) => throw new NotImplementedException();
+            public static StatelessCollectionPinnableReferenceNative AllocateContainerForUnmanagedElements(StatelessCollectionPinnableReference<T> managed, out int numElements) => throw new NotImplementedException();
+            public static StatelessCollectionPinnableReference<T> AllocateContainerForManagedElements(StatelessCollectionPinnableReferenceNative unmanaged, int numElements) => throw new NotImplementedException();
+            public static ReadOnlySpan<T> GetManagedValuesSource(StatelessCollectionPinnableReference<T> managed) => throw new NotImplementedException();
+            public static Span<TUnmanaged> GetUnmanagedValuesDestination(StatelessCollectionPinnableReferenceNative unmanaged, int numElements) => throw new NotImplementedException();
+            public static ReadOnlySpan<TUnmanaged> GetUnmanagedValuesSource(StatelessCollectionPinnableReferenceNative unmanaged, int numElements) => throw new NotImplementedException();
+            public static Span<T> GetManagedValuesDestination(StatelessCollectionPinnableReference<T> managed) => throw new NotImplementedException();
+            public static void Free(StatelessCollectionPinnableReferenceNative native) { }
+        }
+
+        public static class UnmanagedToManaged
+        {
+            public static StatelessCollectionPinnableReference<T> AllocateContainerForManagedElements(StatelessCollectionPinnableReferenceNative unmanaged, int numElements) => throw new NotImplementedException();
+            public static ReadOnlySpan<TUnmanaged> GetUnmanagedValuesSource(StatelessCollectionPinnableReferenceNative unmanaged, int numElements) => throw new NotImplementedException();
+            public static Span<T> GetManagedValuesDestination(StatelessCollectionPinnableReference<T> managed) => throw new NotImplementedException();
+            public static void Free(StatelessCollectionPinnableReferenceNative native) { }
+        }
+
+        public static class ManagedToUnmanaged
+        {
+            public static ref StatelessCollectionPinnableReferenceNative GetPinnableReference(StatelessCollectionPinnableReference<T> managed) => throw new NotImplementedException();
+            public static StatelessCollectionPinnableReferenceNative AllocateContainerForUnmanagedElements(StatelessCollectionPinnableReference<T> managed, out int numElements) => throw new NotImplementedException();
+            public static ReadOnlySpan<T> GetManagedValuesSource(StatelessCollectionPinnableReference<T> managed) => throw new NotImplementedException();
+            public static Span<TUnmanaged> GetUnmanagedValuesDestination(StatelessCollectionPinnableReferenceNative unmanaged, int numElements) => throw new NotImplementedException();
+            public static void Free(StatelessCollectionPinnableReferenceNative native) { }
+        }
+    }
+}