Add IterationDataAttribute (#4561)

Author: sharwell

test/Microsoft.ML.TestFrameworkCommon/Attributes/IterationDataAttribute.cs

@@ -0,0 +1,37 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.Reflection;
+using Xunit.Sdk;
+
+namespace Microsoft.ML.TestFrameworkCommon.Attributes
+{
+    /// <summary>
+    /// xUnit data attribute that allows looping tests. The following example shows a test which will run 50 times.
+    /// <code>
+    /// [Theory, IterationData(50)]
+    /// public void IteratingTest(int iteration)
+    /// {
+    /// }
+    /// </code>
+    /// </summary>
+    public sealed class IterationDataAttribute : DataAttribute
+    {
+        public IterationDataAttribute(int iterations = 100)
+        {
+            Iterations = iterations;
+        }
+
+        public int Iterations { get; }
+
+        public override IEnumerable<object[]> GetData(MethodInfo testMethod)
+        {
+            for (var i = 0; i < Iterations; i++)
+            {
+                yield return new object[] { i };
+            }
+        }
+    }
+}