Moving AsyncEnumerator tests.

Ix.NET/Source/System.Interactive.Async.Tests/AsyncTests.Single.cs

@@ -11,14 +11,6 @@ namespace Tests
 {
     public partial class AsyncTests
     {
-        [Fact]
-        public void MoveNextExtension_Null()
-        {
-            var en = default(IAsyncEnumerator<int>);
-
-            Assert.ThrowsAsync<ArgumentNullException>(() => en.MoveNextAsync());
-        }
-
         [Fact]
         public void SelectWhere2()
         {

Ix.NET/Source/System.Linq.Async.Tests/System/Linq/AsyncEnumeratorTests.cs

@@ -0,0 +1,21 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information. 
+
+using System;
+using System.Collections.Generic;
+using Xunit;
+
+namespace Tests
+{
+    public class AsyncEnumeratorTests
+    {
+        [Fact]
+        public void MoveNextExtension_Null()
+        {
+            var en = default(IAsyncEnumerator<int>);
+
+            Assert.ThrowsAsync<ArgumentNullException>(() => en.MoveNextAsync());
+        }
+    }
+}