Moving IsEmpty tests.

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

@@ -5,10 +5,9 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using Xunit;
-using System.Collections;
 using System.Threading;
 using System.Threading.Tasks;
+using Xunit;
 // ReSharper disable InvokeAsExtensionMethod
 // ReSharper disable InconsistentNaming
 // ReSharper disable RedundantTypeArgumentsOfMethod
@@ -19,13 +18,6 @@ namespace Tests
     {
         private const int WaitTimeoutMs = 5000;
 
-        [Fact]
-        public async Task IsEmpty_Null()
-        {
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerableEx.IsEmpty<int>(null));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerableEx.IsEmpty<int>(null, CancellationToken.None));
-        }
-
         [Fact]
         public async Task Min_Null()
         {

Ix.NET/Source/System.Interactive.Async.Tests/System/Linq/Operators/IsEmpty.cs

@@ -0,0 +1,22 @@
+// 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.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Tests
+{
+    public class IsEmpty : AsyncEnumerableExTests
+    {
+        [Fact]
+        public async Task IsEmpty_Null()
+        {
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerableEx.IsEmpty<int>(null));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerableEx.IsEmpty<int>(null, CancellationToken.None));
+        }
+    }
+}