eliminate crosstalk between C# tests

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

@@ -141,7 +141,8 @@ namespace Grpc.Core.Tests
         {
             if (server == null)
             {
-                server = new Server
+                // Disable SO_REUSEPORT to prevent https://github.com/grpc/grpc/issues/10755
+                server = new Server(new[] { new ChannelOption(ChannelOptions.SoReuseport, 0) })
                 {
                     Services = { serviceDefinition },
                     Ports = { { Host, ServerPort.PickUnused, ServerCredentials.Insecure } }

src/csharp/Grpc.Examples.Tests/MathClientServerTests.cs

@@ -55,7 +55,8 @@ namespace Math.Tests
         [TestFixtureSetUp]
         public void Init()
         {
-            server = new Server
+            // Disable SO_REUSEPORT to prevent https://github.com/grpc/grpc/issues/10755
+            server = new Server(new[] { new ChannelOption(ChannelOptions.SoReuseport, 0) })
             {
                 Services = { Math.BindService(new MathServiceImpl()) },
                 Ports = { { Host, ServerPort.PickUnused, ServerCredentials.Insecure } }

src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs

@@ -57,7 +57,8 @@ namespace Grpc.HealthCheck.Tests
         {
             serviceImpl = new HealthServiceImpl();
 
-            server = new Server
+            // Disable SO_REUSEPORT to prevent https://github.com/grpc/grpc/issues/10755
+            server = new Server(new[] { new ChannelOption(ChannelOptions.SoReuseport, 0) })
             {
                 Services = { Grpc.Health.V1.Health.BindService(serviceImpl) },
                 Ports = { { Host, ServerPort.PickUnused, ServerCredentials.Insecure } }

src/csharp/Grpc.IntegrationTesting/GeneratedServiceBaseTest.cs

@@ -54,7 +54,8 @@ namespace Grpc.IntegrationTesting
         [SetUp]
         public void Init()
         {
-            server = new Server
+            // Disable SO_REUSEPORT to prevent https://github.com/grpc/grpc/issues/10755
+            server = new Server(new[] { new ChannelOption(ChannelOptions.SoReuseport, 0) })
             {
                 Services = { TestService.BindService(new UnimplementedTestServiceImpl()) },
                 Ports = { { Host, ServerPort.PickUnused, SslServerCredentials.Insecure } }

src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs

@@ -56,7 +56,8 @@ namespace Grpc.IntegrationTesting
         [TestFixtureSetUp]
         public void Init()
         {
-            server = new Server
+            // Disable SO_REUSEPORT to prevent https://github.com/grpc/grpc/issues/10755
+            server = new Server(new[] { new ChannelOption(ChannelOptions.SoReuseport, 0) })
             {
                 Services = { TestService.BindService(new TestServiceImpl()) },
                 Ports = { { Host, ServerPort.PickUnused, TestCredentials.CreateSslServerCredentials() } }

src/csharp/Grpc.IntegrationTesting/MetadataCredentialsTest.cs

@@ -56,7 +56,8 @@ namespace Grpc.IntegrationTesting
         [SetUp]
         public void Init()
         {
-            server = new Server
+            // Disable SO_REUSEPORT to prevent https://github.com/grpc/grpc/issues/10755
+            server = new Server(new[] { new ChannelOption(ChannelOptions.SoReuseport, 0) })
             {
                 Services = { TestService.BindService(new FakeTestService()) },
                 Ports = { { Host, ServerPort.PickUnused, TestCredentials.CreateSslServerCredentials() } }

src/csharp/Grpc.IntegrationTesting/SslCredentialsTest.cs

@@ -67,7 +67,8 @@ namespace Grpc.IntegrationTesting
             var serverCredentials = new SslServerCredentials(new[] { keyCertPair }, rootCert, true);
             var clientCredentials = new SslCredentials(rootCert, keyCertPair);
 
-            server = new Server
+            // Disable SO_REUSEPORT to prevent https://github.com/grpc/grpc/issues/10755
+            server = new Server(new[] { new ChannelOption(ChannelOptions.SoReuseport, 0) })
             {
                 Services = { TestService.BindService(new SslCredentialsTestServiceImpl()) },
                 Ports = { { Host, ServerPort.PickUnused, serverCredentials } }

src/csharp/Grpc.Reflection.Tests/ReflectionClientServerTest.cs

@@ -58,7 +58,8 @@ namespace Grpc.Reflection.Tests
         {
             serviceImpl = new ReflectionServiceImpl(ServerReflection.Descriptor);
 
-            server = new Server
+            // Disable SO_REUSEPORT to prevent https://github.com/grpc/grpc/issues/10755
+            server = new Server(new[] { new ChannelOption(ChannelOptions.SoReuseport, 0) })
             {
                 Services = { ServerReflection.BindService(serviceImpl) },
                 Ports = { { Host, ServerPort.PickUnused, ServerCredentials.Insecure } }