Implement `OwinEnvironment` `IEnumerable.GetEnumerator()` (#789)

src/Microsoft.AspNetCore.Owin/OwinEnvironment.cs

@@ -270,7 +270,7 @@ namespace Microsoft.AspNetCore.Owin
             throw new NotImplementedException();
         }
 
-        IEnumerator<KeyValuePair<string, object>> IEnumerable<KeyValuePair<string, object>>.GetEnumerator()
+        public IEnumerator<KeyValuePair<string, object>> GetEnumerator()
         {
             foreach (var entryPair in _entries)
             {
@@ -288,7 +288,7 @@ namespace Microsoft.AspNetCore.Owin
 
         IEnumerator IEnumerable.GetEnumerator()
         {
-            throw new NotImplementedException();
+            return GetEnumerator();
         }
 
         public class FeatureMap

test/Microsoft.AspNetCore.Owin.Tests/OwinEnvironmentTests.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Collections;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -129,6 +130,15 @@ namespace Microsoft.AspNetCore.Owin
             Assert.Equal("1.0", env["owin.Version"]);
         }
 
+        [Fact]
+        public void OwinEnvironmentImpelmentsGetEnumerator()
+        {
+            var owinEnvironment = new OwinEnvironment(CreateContext());
+
+            Assert.NotNull(owinEnvironment.GetEnumerator());
+            Assert.NotNull(((IEnumerable)owinEnvironment).GetEnumerator());
+        }
+
         private HttpContext CreateContext()
         {
             var context = new DefaultHttpContext();