C#: fix subchannel sharing for secure channels

2 files changed, 31 insertions, 16 deletions

diff --git a/src/csharp/Grpc.Core.Tests/ChannelCredentialsTest.cs b/src/csharp/Grpc.Core.Tests/ChannelCredentialsTest.cs
index 62cc904a61..843d88bfb6 100644
--- a/src/csharp/Grpc.Core.Tests/ChannelCredentialsTest.cs
+++ b/src/csharp/Grpc.Core.Tests/ChannelCredentialsTest.cs
@@ -17,13 +17,7 @@
 #endregion
 
 using System;
-using System.Diagnostics;
-using System.Runtime.InteropServices;
-using System.Threading;
-using System.Threading.Tasks;
-using Grpc.Core;
 using Grpc.Core.Internal;
-using Grpc.Core.Utils;
 using NUnit.Framework;
 
 namespace Grpc.Core.Tests
@@ -44,9 +38,38 @@ namespace Grpc.Core.Tests
 
             Assert.Throws(typeof(ArgumentNullException), () => ChannelCredentials.Create(null, new FakeCallCredentials()));
             Assert.Throws(typeof(ArgumentNullException), () => ChannelCredentials.Create(new FakeChannelCredentials(true), null));
-            
+
             // forbid composing non-composable
             Assert.Throws(typeof(ArgumentException), () => ChannelCredentials.Create(new FakeChannelCredentials(false), new FakeCallCredentials()));
         }
+
+        [Test]
+        public void ChannelCredentials_NativeCredentialsAreReused()
+        {
+            // always returning the same native object is critical for subchannel sharing to work with secure channels
+            var creds = new SslCredentials();
+            var nativeCreds1 = creds.GetNativeCredentials();
+            var nativeCreds2 = creds.GetNativeCredentials();
+            Assert.AreSame(nativeCreds1, nativeCreds2);
+        }
+
+        [Test]
+        public void ChannelCredentials_CreateExceptionIsCached()
+        {
+            var creds = new ChannelCredentialsWithCreateNativeThrows();
+            var ex1 = Assert.Throws(typeof(Exception), () => creds.GetNativeCredentials());
+            var ex2 = Assert.Throws(typeof(Exception), () => creds.GetNativeCredentials());
+            Assert.AreSame(ex1, ex2);
+        }
+
+        internal class ChannelCredentialsWithCreateNativeThrows : ChannelCredentials
+        {
+            internal override bool IsComposable => false;
+
+            internal override ChannelCredentialsSafeHandle CreateNativeCredentials()
+            {
+                throw new Exception("Creation of native credentials has failed on purpose.");
+            }
+        }
     }
 }
diff --git a/src/csharp/Grpc.Core.Tests/FakeCredentials.cs b/src/csharp/Grpc.Core.Tests/FakeCredentials.cs
index 7d658576e5..f23c9e9757 100644
--- a/src/csharp/Grpc.Core.Tests/FakeCredentials.cs
+++ b/src/csharp/Grpc.Core.Tests/FakeCredentials.cs
@@ -16,15 +16,7 @@
 
 #endregion
 
-using System;
-using System.Diagnostics;
-using System.Runtime.InteropServices;
-using System.Threading;
-using System.Threading.Tasks;
-using Grpc.Core;
 using Grpc.Core.Internal;
-using Grpc.Core.Utils;
-using NUnit.Framework;
 
 namespace Grpc.Core.Tests
 {
@@ -42,7 +34,7 @@ namespace Grpc.Core.Tests
             get { return composable; }
         }
 
-        internal override ChannelCredentialsSafeHandle ToNativeCredentials()
+        internal override ChannelCredentialsSafeHandle CreateNativeCredentials()
         {
             return null;
         }