C# add RetryTest with service config to reproduce #23618 (#24413)

* C# add RetryTest with service config to reproduce #23618

* fixup tests

src/csharp/Grpc.Core.Tests/RetryTest.cs

@@ -0,0 +1,119 @@
+#region Copyright notice and license
+
+// Copyright 2020 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#endregion
+
+using System;
+using System.Diagnostics;
+using System.Linq;
+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
+{
+    /// <summary>
+    /// Tests for service-config based retries.
+    /// </summary>
+    public class RetryTest
+    {
+        MockServiceHelper helper;
+        Server server;
+        Channel channel;
+
+        [SetUp]
+        public void Init()
+        {
+            var channelOptions = new ChannelOption[]
+            {
+                new ChannelOption(
+                    "grpc.service_config",
+                    "{\"methodConfig\":[{\"name\":[{\"service\":\"" + MockServiceHelper.ServiceName + "\",\"method\":\"Unary\"}],\"retryPolicy\":{\"maxAttempts\":3,\"initialBackoff\":\"0.5s\",\"maxBackoff\":\"5s\",\"backoffMultiplier\":2.0,\"retryableStatusCodes\":[\"UNAVAILABLE\"]}}, {\"name\":[{\"service\":\"" + MockServiceHelper.ServiceName + "\",\"method\":\"ServerStreaming\"}],\"retryPolicy\":{\"maxAttempts\":3,\"initialBackoff\":\"0.5s\",\"maxBackoff\":\"5s\",\"backoffMultiplier\":2.0,\"retryableStatusCodes\":[\"UNAVAILABLE\"]}}]}")
+            };
+            helper = new MockServiceHelper(channelOptions: channelOptions);
+
+            server = helper.GetServer();
+            server.Start();
+            channel = helper.GetChannel();
+        }
+
+        [TearDown]
+        public void Cleanup()
+        {
+            channel.ShutdownAsync().Wait();
+            server.ShutdownAsync().Wait();
+        }
+
+        [Test]
+        public void ServiceConfigRetryPolicy_UnaryCall()
+        {
+            var counter = new AtomicCounter();
+
+            helper.UnaryHandler = new UnaryServerMethod<string, string>((request, context) =>
+            {
+                var attempt = counter.Increment();
+                if (attempt <= 2)
+                {
+                    throw new RpcException(new Status(StatusCode.Unavailable, $"Attempt {attempt} failed on purpose"));
+                }
+                return Task.FromResult("PASS");
+            });
+
+            Assert.AreEqual("PASS", Calls.BlockingUnaryCall(helper.CreateUnaryCall(), "abc"));
+        }
+
+        [Test]
+        public async Task ServiceConfigRetryPolicy_AsyncUnaryCall()
+        {
+            var counter = new AtomicCounter();
+
+            helper.UnaryHandler = new UnaryServerMethod<string, string>((request, context) =>
+            {
+                var attempt = counter.Increment();
+                if (attempt <= 2)
+                {
+                    throw new RpcException(new Status(StatusCode.Unavailable, $"Attempt {attempt} failed on purpose"));
+                }
+                return Task.FromResult("PASS");
+            });
+
+            Assert.AreEqual("PASS", await Calls.AsyncUnaryCall(helper.CreateUnaryCall(), "abc"));
+        }
+
+        [Test]
+        public async Task ServiceConfigRetryPolicy_ServerStreaming()
+        {
+            var counter = new AtomicCounter();
+
+            helper.ServerStreamingHandler = new ServerStreamingServerMethod<string, string>(async (request, responseStream, context) =>
+            {
+                var attempt = counter.Increment();
+                if (attempt <= 2)
+                {
+                    throw new RpcException(new Status(StatusCode.Unavailable, $"Attempt {attempt} failed on purpose"));
+                }
+                await responseStream.WriteAllAsync(request.Split(new []{' '}));
+            });
+
+            var call = Calls.AsyncServerStreamingCall(helper.CreateServerStreamingCall(), "A B C");
+            CollectionAssert.AreEqual(new string[] { "A", "B", "C" }, await call.ResponseStream.ToListAsync());
+            Assert.AreEqual(StatusCode.OK, call.GetStatus().StatusCode);
+        }
+    }
+}

src/csharp/tests.json

@@ -42,6 +42,7 @@
     "Grpc.Core.Tests.PerformanceTest",
     "Grpc.Core.Tests.PInvokeTest",
     "Grpc.Core.Tests.ResponseHeadersTest",
+    "Grpc.Core.Tests.RetryTest",
     "Grpc.Core.Tests.SanityTest",
     "Grpc.Core.Tests.ServerBindFailedTest",
     "Grpc.Core.Tests.ServerTest",