implement per_rpc_creds and oauth2_auth_token interop tests

src/csharp/Grpc.Auth/GoogleCredential.cs

@@ -35,8 +35,11 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Security.Cryptography;
+using System.Threading;
+using System.Threading.Tasks;
 
 using Google.Apis.Auth.OAuth2;
+using Google.Apis.Auth.OAuth2.Responses;
 using Newtonsoft.Json.Linq;
 using Org.BouncyCastle.Crypto.Parameters;
 using Org.BouncyCastle.Security;
@@ -100,6 +103,19 @@ namespace Grpc.Auth
             return new GoogleCredential(serviceCredential);
         }
 
+        public Task<bool> RequestAccessTokenAsync(CancellationToken taskCancellationToken)
+        {
+            return credential.RequestAccessTokenAsync(taskCancellationToken);
+        }
+
+        public TokenResponse Token
+        {
+            get
+            {
+                return credential.Token;
+            }
+        }
+
         internal ServiceCredential InternalCredential
         {
             get

src/csharp/Grpc.Core.Tests/Internal/MetadataArraySafeHandleTest.cs

@@ -51,7 +51,8 @@ namespace Grpc.Core.Internal.Tests
         [Test]
         public void CreateAndDestroy()
         {
-            var metadata = new Metadata {
+            var metadata = new Metadata
+            {
                 new Metadata.Entry("host", "somehost"),
                 new Metadata.Entry("header2", "header value"),
             };

src/csharp/Grpc.IntegrationTesting/InteropClient.cs

@@ -135,7 +135,7 @@ namespace Grpc.IntegrationTesting
             GrpcEnvironment.Shutdown();
         }
 
-        private void RunTestCase(string testCase, TestService.ITestServiceClient client)
+        private void RunTestCase(string testCase, TestService.TestServiceClient client)
         {
             switch (testCase)
             {
@@ -163,6 +163,12 @@ namespace Grpc.IntegrationTesting
                 case "compute_engine_creds":
                     RunComputeEngineCreds(client);
                     break;
+                case "oauth2_auth_token":
+                    RunOAuth2AuthToken(client);
+                    break;
+                case "per_rpc_creds":
+                    RunPerRpcCreds(client);
+                    break;
                 case "cancel_after_begin":
                     RunCancelAfterBegin(client);
                     break;
@@ -355,6 +361,51 @@ namespace Grpc.IntegrationTesting
             Console.WriteLine("Passed!");
         }
 
+        public static void RunOAuth2AuthToken(TestService.TestServiceClient client)
+        {
+            Console.WriteLine("running oauth2_auth_token");
+            var credential = GoogleCredential.GetApplicationDefault().CreateScoped(new[] { AuthScope });
+            Assert.IsTrue(credential.RequestAccessTokenAsync(CancellationToken.None).Result);
+            string oauth2Token = credential.Token.AccessToken;
+
+            // Intercept calls with an OAuth2 token obtained out-of-band.
+            client.HeaderInterceptor = new MetadataInterceptorDelegate((metadata) =>
+            {
+                metadata.Add(new Metadata.Entry("Authorization", "Bearer " + oauth2Token));
+            });
+
+            var request = SimpleRequest.CreateBuilder()
+                .SetFillUsername(true)
+                .SetFillOauthScope(true)
+                .Build();
+
+            var response = client.UnaryCall(request);
+
+            Assert.AreEqual(AuthScopeResponse, response.OauthScope);
+            Assert.AreEqual(ServiceAccountUser, response.Username);
+            Console.WriteLine("Passed!");
+        }
+
+        public static void RunPerRpcCreds(TestService.TestServiceClient client)
+        {
+            Console.WriteLine("running per_rpc_creds");
+
+            var credential = GoogleCredential.GetApplicationDefault().CreateScoped(new[] { AuthScope });
+            Assert.IsTrue(credential.RequestAccessTokenAsync(CancellationToken.None).Result);
+            string oauth2Token = credential.Token.AccessToken;
+
+            var request = SimpleRequest.CreateBuilder()
+                .SetFillUsername(true)
+                .SetFillOauthScope(true)
+                .Build();
+
+            var response = client.UnaryCall(request, headers: new Metadata { new Metadata.Entry("Authorization", "Bearer " + oauth2Token) } );
+
+            Assert.AreEqual(AuthScopeResponse, response.OauthScope);
+            Assert.AreEqual(ServiceAccountUser, response.Username);
+            Console.WriteLine("Passed!");
+        }
+
         public static void RunCancelAfterBegin(TestService.ITestServiceClient client)
         {
             Task.Run(async () =>