3 files changed, 97 insertions, 1 deletions
diff --git a/src/csharp/Grpc.Core/ClientBase.cs b/src/csharp/Grpc.Core/ClientBase.cs
index 98db9b8a6f..265e6c5c07 100644
--- a/src/csharp/Grpc.Core/ClientBase.cs
+++ b/src/csharp/Grpc.Core/ClientBase.cs
@@ -42,9 +42,19 @@ namespace Grpc.Core
     /// Generic base class for client-side stubs.
     /// </summary>
     public abstract class ClientBase<T> : ClientBase
-        where T : ClientBase
+        where T : ClientBase<T>
     {
         /// <summary>
+        /// Initializes a new instance of <c>ClientBase</c> class that
+        /// throws <c>NotImplementedException</c> upon invocation of any RPC.
+        /// This constructor is only provided to allow creation of test doubles
+        /// for client classes (e.g. mocking requires a parameterless constructor).
+        /// </summary>
+        protected ClientBase() : base()
+        {
+        }
+
+        /// <summary>
         /// Initializes a new instance of <c>ClientBase</c> class.
         /// </summary>
         /// <param name="channel">The channel to use for remote call invocation.</param>
@@ -87,6 +97,16 @@ namespace Grpc.Core
         readonly CallInvoker callInvoker;
 
         /// <summary>
+        /// Initializes a new instance of <c>ClientBase</c> class that
+        /// throws <c>NotImplementedException</c> upon invocation of any RPC.
+        /// This constructor is only provided to allow creation of test doubles
+        /// for client classes (e.g. mocking requires a parameterless constructor).
+        /// </summary>
+        protected ClientBase() : this(new UnimplementedCallInvoker())
+        {
+        }
+
+        /// <summary>
         /// Initializes a new instance of <c>ClientBase</c> class.
         /// </summary>
         /// <param name="channel">The channel to use for remote call invocation.</param>
diff --git a/src/csharp/Grpc.Core/Grpc.Core.csproj b/src/csharp/Grpc.Core/Grpc.Core.csproj
index 1d3b01a534..7d950bd978 100644
--- a/src/csharp/Grpc.Core/Grpc.Core.csproj
+++ b/src/csharp/Grpc.Core/Grpc.Core.csproj
@@ -132,6 +132,7 @@
     <Compile Include="CallInvoker.cs" />
     <Compile Include="DefaultCallInvoker.cs" />
     <Compile Include="InterceptingCallInvoker.cs" />
+    <Compile Include="UnimplementedCallInvoker.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="Grpc.Core.nuspec" />
diff --git a/src/csharp/Grpc.Core/UnimplementedCallInvoker.cs b/src/csharp/Grpc.Core/UnimplementedCallInvoker.cs
new file mode 100644
index 0000000000..7f046cbca9
--- /dev/null
+++ b/src/csharp/Grpc.Core/UnimplementedCallInvoker.cs
@@ -0,0 +1,75 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Threading.Tasks;
+using Grpc.Core.Internal;
+using Grpc.Core.Utils;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// Call invoker that throws <c>NotImplementedException</c> for all requests.
+    /// </summary>
+    internal class UnimplementedCallInvoker : CallInvoker
+    {
+        public UnimplementedCallInvoker()
+        {
+        }
+
+        public override TResponse BlockingUnaryCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options, TRequest request)
+        {
+            throw new NotImplementedException();
+        }
+
+        public override AsyncUnaryCall<TResponse> AsyncUnaryCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options, TRequest request)
+        {
+            throw new NotImplementedException();
+        }
+
+        public override AsyncServerStreamingCall<TResponse> AsyncServerStreamingCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options, TRequest request)
+        {
+            throw new NotImplementedException();
+        }
+
+        public override AsyncClientStreamingCall<TRequest, TResponse> AsyncClientStreamingCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options)
+        {
+            throw new NotImplementedException();
+        }
+
+        public override AsyncDuplexStreamingCall<TRequest, TResponse> AsyncDuplexStreamingCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}