5 files changed, 38 insertions, 21 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;
         }
diff --git a/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj b/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
index 18993a93e0..d58f046824 100755
--- a/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
+++ b/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
@@ -17,8 +17,8 @@
 
   <ItemGroup>
     <PackageReference Include="Newtonsoft.Json" Version="9.0.1" />
-    <PackageReference Include="NUnit" Version="3.6.0" />
-    <PackageReference Include="NUnitLite" Version="3.6.0" />
+    <PackageReference Include="NUnit" Version="3.10.1" />
+    <PackageReference Include="NUnitLite" Version="3.10.1" />
     <PackageReference Include="OpenCover" Version="4.6.519" />
     <PackageReference Include="ReportGenerator" Version="2.4.4.0" />
   </ItemGroup>
diff --git a/src/csharp/Grpc.Core.Tests/MetadataTest.cs b/src/csharp/Grpc.Core.Tests/MetadataTest.cs
index 8916731757..171c5c470e 100644
--- a/src/csharp/Grpc.Core.Tests/MetadataTest.cs
+++ b/src/csharp/Grpc.Core.Tests/MetadataTest.cs
@@ -66,6 +66,8 @@ namespace Grpc.Core.Tests
             new Metadata.Entry("0123456789abc", "XYZ");
             new Metadata.Entry("-abc", "XYZ");
             new Metadata.Entry("a_bc_", "XYZ");
+            new Metadata.Entry("abc.xyz", "XYZ");
+            new Metadata.Entry("abc.xyz-bin", new byte[] {1, 2, 3});
             Assert.Throws(typeof(ArgumentException), () => new Metadata.Entry("abc[", "xyz"));
             Assert.Throws(typeof(ArgumentException), () => new Metadata.Entry("abc/", "xyz"));
         }
diff --git a/src/csharp/Grpc.Core.Tests/SanityTest.cs b/src/csharp/Grpc.Core.Tests/SanityTest.cs
index 73efad1f84..eaad409ec0 100644
--- a/src/csharp/Grpc.Core.Tests/SanityTest.cs
+++ b/src/csharp/Grpc.Core.Tests/SanityTest.cs
@@ -65,13 +65,13 @@ namespace Grpc.Core.Tests
                 {
                     foreach (var m in t.GetMethods())
                     {
-                        var attributes = m.GetCustomAttributes(typeof(NUnit.Framework.TestAttribute), true);
-                        if (attributes.Length > 0)
+                        var testAttributes = m.GetCustomAttributes(typeof(NUnit.Framework.TestAttribute), true);
+                        var testCaseAttributes = m.GetCustomAttributes(typeof(NUnit.Framework.TestCaseAttribute), true);
+                        if (testAttributes.Length > 0 || testCaseAttributes.Length > 0)
                         {
                             testClasses.Add(t.FullName);
                             break;
                         }
-
                     }
                 }
                 testClasses.Sort();