Simplify helper method

TeachingRecordSystem/tests/TeachingRecordSystem.TestCommon/MockExtensions.cs

@@ -9,16 +9,6 @@ public static IReturnsResult<T> ReturnsAsyncEnumerable<T, TResult>(
             params TResult[] items)
         where T : class
     {
-        return setup.Returns(GetAsyncEnumerableAsync(items));
-
-#pragma warning disable CS1998 // Async method lacks 'await' operators and will run synchronously
-        static async IAsyncEnumerable<R> GetAsyncEnumerableAsync<R>(IEnumerable<R> enumerable)
-        {
-            foreach (var item in enumerable)
-            {
-                yield return item;
-            }
-        }
-#pragma warning restore CS1998 // Async method lacks 'await' operators and will run synchronously
+        return setup.Returns(items.ToAsyncEnumerable());
     }
 }