Moving Average tests.

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

@@ -873,246 +873,6 @@ namespace Tests
             Assert.True(res.Count == 2);
         }
 
-        [Fact]
-        public async Task Average_Null()
-        {
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int?>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long?>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double?>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float?>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal?>)));
-
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int>), x => x));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int?>), x => x));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long>), x => x));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long?>), x => x));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double>), x => x));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double?>), x => x));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float>), x => x));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float?>), x => x));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal>), x => x));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal?>), x => x));
-
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, int>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, int?>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, long>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, long?>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, double>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, double?>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, float>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, float?>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, decimal>)));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, decimal?>)));
-
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int?>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long?>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double?>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float?>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal?>), CancellationToken.None));
-
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int>), x => x, CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int?>), x => x, CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long>), x => x, CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long?>), x => x, CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double>), x => x, CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double?>), x => x, CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float>), x => x, CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float?>), x => x, CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal>), x => x, CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal?>), x => x, CancellationToken.None));
-
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, int>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, int?>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, long>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, long?>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, double>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, double?>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, float>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, float?>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, decimal>), CancellationToken.None));
-            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, decimal?>), CancellationToken.None));
-        }
-
-        [Fact]
-        public void Average1()
-        {
-            var xs = new[] { 1, 2, 3 };
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Equal(xs.Average(), ys.Average().Result);
-            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
-        }
-
-        [Fact]
-        public void Average2()
-        {
-            var xs = new[] { 1, default(int?), 3 };
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Equal(xs.Average(), ys.Average().Result);
-            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
-        }
-
-        [Fact]
-        public void Average3()
-        {
-            var xs = new[] { 1L, 2L, 3L };
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Equal(xs.Average(), ys.Average().Result);
-            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
-        }
-
-        [Fact]
-        public void Average4()
-        {
-            var xs = new[] { 1L, default(long?), 3L };
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Equal(xs.Average(), ys.Average().Result);
-            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
-        }
-
-        [Fact]
-        public void Average5()
-        {
-            var xs = new[] { 1.0, 2.0, 3.0 };
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Equal(xs.Average(), ys.Average().Result);
-            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
-        }
-
-        [Fact]
-        public void Average6()
-        {
-            var xs = new[] { 1.0, default(double?), 3.0 };
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Equal(xs.Average(), ys.Average().Result);
-            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
-        }
-
-        [Fact]
-        public void Average7()
-        {
-            var xs = new[] { 1.0f, 2.0f, 3.0f };
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Equal(xs.Average(), ys.Average().Result);
-            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
-        }
-
-        [Fact]
-        public void Average8()
-        {
-            var xs = new[] { 1.0f, default(float?), 3.0f };
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Equal(xs.Average(), ys.Average().Result);
-            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
-        }
-
-        [Fact]
-        public void Average9()
-        {
-            var xs = new[] { 1.0m, 2.0m, 3.0m };
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Equal(xs.Average(), ys.Average().Result);
-            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
-        }
-
-        [Fact]
-        public void Average10()
-        {
-            var xs = new[] { 1.0m, default(decimal?), 3.0m };
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Equal(xs.Average(), ys.Average().Result);
-            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
-        }
-
-        [Fact]
-        public void Average11()
-        {
-            var xs = new int[0];
-            var ys = xs.ToAsyncEnumerable();
-            AssertThrows<Exception>(() => ys.Average().Wait(WaitTimeoutMs), ex_ => ((AggregateException)ex_).Flatten().InnerExceptions.Single() is InvalidOperationException);
-        }
-
-        [Fact]
-        public void Average12()
-        {
-            var xs = new int?[0];
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Null(ys.Average().Result);
-        }
-
-        [Fact]
-        public void Average13()
-        {
-            var xs = new long[0];
-            var ys = xs.ToAsyncEnumerable();
-            AssertThrows<Exception>(() => ys.Average().Wait(WaitTimeoutMs), ex_ => ((AggregateException)ex_).Flatten().InnerExceptions.Single() is InvalidOperationException);
-        }
-
-        [Fact]
-        public void Average14()
-        {
-            var xs = new long?[0];
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Null(ys.Average().Result);
-        }
-
-        [Fact]
-        public void Average15()
-        {
-            var xs = new double[0];
-            var ys = xs.ToAsyncEnumerable();
-            AssertThrows<Exception>(() => ys.Average().Wait(WaitTimeoutMs), ex_ => ((AggregateException)ex_).Flatten().InnerExceptions.Single() is InvalidOperationException);
-        }
-
-        [Fact]
-        public void Average16()
-        {
-            var xs = new double?[0];
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Null(ys.Average().Result);
-        }
-
-        [Fact]
-        public void Average17()
-        {
-            var xs = new float[0];
-            var ys = xs.ToAsyncEnumerable();
-            AssertThrows<Exception>(() => ys.Average().Wait(WaitTimeoutMs), ex_ => ((AggregateException)ex_).Flatten().InnerExceptions.Single() is InvalidOperationException);
-        }
-
-        [Fact]
-        public void Average18()
-        {
-            var xs = new float?[0];
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Null(ys.Average().Result);
-        }
-
-        [Fact]
-        public void Average19()
-        {
-            var xs = new decimal[0];
-            var ys = xs.ToAsyncEnumerable();
-            AssertThrows<Exception>(() => ys.Average().Wait(WaitTimeoutMs), ex_ => ((AggregateException)ex_).Flatten().InnerExceptions.Single() is InvalidOperationException);
-        }
-
-        [Fact]
-        public void Average20()
-        {
-            var xs = new decimal?[0];
-            var ys = xs.ToAsyncEnumerable();
-            Assert.Null(ys.Average().Result);
-        }
-
         [Fact]
         public async Task Min_Null()
         {

Ix.NET/Source/System.Linq.Async.Tests/System/Linq/Operators/Average.cs

@@ -0,0 +1,256 @@
+// 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 System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Tests
+{
+    public class Average : AsyncEnumerableTests
+    {
+        [Fact]
+        public async Task Average_Null()
+        {
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int?>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long?>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double?>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float?>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal?>)));
+
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int>), x => x));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int?>), x => x));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long>), x => x));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long?>), x => x));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double>), x => x));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double?>), x => x));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float>), x => x));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float?>), x => x));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal>), x => x));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal?>), x => x));
+
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, int>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, int?>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, long>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, long?>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, double>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, double?>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, float>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, float?>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, decimal>)));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, decimal?>)));
+
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int?>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long?>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double?>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float?>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal?>), CancellationToken.None));
+
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int>), x => x, CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<int?>), x => x, CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long>), x => x, CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<long?>), x => x, CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double>), x => x, CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<double?>), x => x, CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float>), x => x, CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<float?>), x => x, CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal>), x => x, CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(default(IAsyncEnumerable<decimal?>), x => x, CancellationToken.None));
+
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, int>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, int?>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, long>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, long?>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, double>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, double?>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, float>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, float?>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, decimal>), CancellationToken.None));
+            await Assert.ThrowsAsync<ArgumentNullException>(() => AsyncEnumerable.Average(AsyncEnumerable.Empty<int>(), default(Func<int, decimal?>), CancellationToken.None));
+        }
+
+        [Fact]
+        public void Average1()
+        {
+            var xs = new[] { 1, 2, 3 };
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Equal(xs.Average(), ys.Average().Result);
+            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
+        }
+
+        [Fact]
+        public void Average2()
+        {
+            var xs = new[] { 1, default(int?), 3 };
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Equal(xs.Average(), ys.Average().Result);
+            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
+        }
+
+        [Fact]
+        public void Average3()
+        {
+            var xs = new[] { 1L, 2L, 3L };
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Equal(xs.Average(), ys.Average().Result);
+            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
+        }
+
+        [Fact]
+        public void Average4()
+        {
+            var xs = new[] { 1L, default(long?), 3L };
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Equal(xs.Average(), ys.Average().Result);
+            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
+        }
+
+        [Fact]
+        public void Average5()
+        {
+            var xs = new[] { 1.0, 2.0, 3.0 };
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Equal(xs.Average(), ys.Average().Result);
+            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
+        }
+
+        [Fact]
+        public void Average6()
+        {
+            var xs = new[] { 1.0, default(double?), 3.0 };
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Equal(xs.Average(), ys.Average().Result);
+            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
+        }
+
+        [Fact]
+        public void Average7()
+        {
+            var xs = new[] { 1.0f, 2.0f, 3.0f };
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Equal(xs.Average(), ys.Average().Result);
+            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
+        }
+
+        [Fact]
+        public void Average8()
+        {
+            var xs = new[] { 1.0f, default(float?), 3.0f };
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Equal(xs.Average(), ys.Average().Result);
+            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
+        }
+
+        [Fact]
+        public void Average9()
+        {
+            var xs = new[] { 1.0m, 2.0m, 3.0m };
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Equal(xs.Average(), ys.Average().Result);
+            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
+        }
+
+        [Fact]
+        public void Average10()
+        {
+            var xs = new[] { 1.0m, default(decimal?), 3.0m };
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Equal(xs.Average(), ys.Average().Result);
+            Assert.Equal(xs.Average(), ys.Average(x => x).Result);
+        }
+
+        [Fact]
+        public void Average11()
+        {
+            var xs = new int[0];
+            var ys = xs.ToAsyncEnumerable();
+            AssertThrows<Exception>(() => ys.Average().Wait(WaitTimeoutMs), ex_ => ((AggregateException)ex_).Flatten().InnerExceptions.Single() is InvalidOperationException);
+        }
+
+        [Fact]
+        public void Average12()
+        {
+            var xs = new int?[0];
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Null(ys.Average().Result);
+        }
+
+        [Fact]
+        public void Average13()
+        {
+            var xs = new long[0];
+            var ys = xs.ToAsyncEnumerable();
+            AssertThrows<Exception>(() => ys.Average().Wait(WaitTimeoutMs), ex_ => ((AggregateException)ex_).Flatten().InnerExceptions.Single() is InvalidOperationException);
+        }
+
+        [Fact]
+        public void Average14()
+        {
+            var xs = new long?[0];
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Null(ys.Average().Result);
+        }
+
+        [Fact]
+        public void Average15()
+        {
+            var xs = new double[0];
+            var ys = xs.ToAsyncEnumerable();
+            AssertThrows<Exception>(() => ys.Average().Wait(WaitTimeoutMs), ex_ => ((AggregateException)ex_).Flatten().InnerExceptions.Single() is InvalidOperationException);
+        }
+
+        [Fact]
+        public void Average16()
+        {
+            var xs = new double?[0];
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Null(ys.Average().Result);
+        }
+
+        [Fact]
+        public void Average17()
+        {
+            var xs = new float[0];
+            var ys = xs.ToAsyncEnumerable();
+            AssertThrows<Exception>(() => ys.Average().Wait(WaitTimeoutMs), ex_ => ((AggregateException)ex_).Flatten().InnerExceptions.Single() is InvalidOperationException);
+        }
+
+        [Fact]
+        public void Average18()
+        {
+            var xs = new float?[0];
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Null(ys.Average().Result);
+        }
+
+        [Fact]
+        public void Average19()
+        {
+            var xs = new decimal[0];
+            var ys = xs.ToAsyncEnumerable();
+            AssertThrows<Exception>(() => ys.Average().Wait(WaitTimeoutMs), ex_ => ((AggregateException)ex_).Flatten().InnerExceptions.Single() is InvalidOperationException);
+        }
+
+        [Fact]
+        public void Average20()
+        {
+            var xs = new decimal?[0];
+            var ys = xs.ToAsyncEnumerable();
+            Assert.Null(ys.Average().Result);
+        }
+    }
+}