diff --git a/Makefile b/Makefile
index 8294ffed5a9320e472c0a4c871b6424320dde8c6..1f356ceef3b1b27e1faddc072fdff775d120fd9f 100644
--- a/Makefile
+++ b/Makefile
@@ -174,7 +174,7 @@ LD_ubsan = clang
 LDXX_ubsan = clang++
 CPPFLAGS_ubsan = -O0 -fsanitize-coverage=edge -fsanitize=undefined -fno-omit-frame-pointer -Wno-unused-command-line-argument -Wvarargs
 LDFLAGS_ubsan = -fsanitize=undefined,unsigned-integer-overflow
-DEFINES_ubsan = NDEBUG
+DEFINES_ubsan = NDEBUG GRPC_UBSAN
 
 VALID_CONFIG_tsan = 1
 REQUIRE_CUSTOM_LIBRARIES_tsan = 1
@@ -418,7 +418,7 @@ AROPTS = $(GRPC_CROSS_AROPTS) # e.g., rc --target=elf32-little
 USE_BUILT_PROTOC = false
 endif
 
-GTEST_LIB = -Ithird_party/googletest/googletest/include -Ithird_party/googletest/googletest third_party/googletest/googletest/src/gtest-all.cc
+GTEST_LIB = -Ithird_party/googletest/googletest/include -Ithird_party/googletest/googletest third_party/googletest/googletest/src/gtest-all.cc -Ithird_party/googletest/googlemock/include -Ithird_party/googletest/googlemock third_party/googletest/googlemock/src/gmock-all.cc
 GTEST_LIB += -lgflags
 ifeq ($(V),1)
 E = @:
@@ -793,7 +793,7 @@ PROTOBUF_PKG_CONFIG = false
 PC_REQUIRES_GRPCXX =
 PC_LIBS_GRPCXX =
 
-CPPFLAGS := -Ithird_party/googletest/googletest/include $(CPPFLAGS)
+CPPFLAGS := -Ithird_party/googletest/googletest/include -Ithird_party/googletest/googlemock/include $(CPPFLAGS)
 
 PROTOC_PLUGINS_ALL = $(BINDIR)/$(CONFIG)/grpc_cpp_plugin $(BINDIR)/$(CONFIG)/grpc_csharp_plugin $(BINDIR)/$(CONFIG)/grpc_node_plugin $(BINDIR)/$(CONFIG)/grpc_objective_c_plugin $(BINDIR)/$(CONFIG)/grpc_php_plugin $(BINDIR)/$(CONFIG)/grpc_python_plugin $(BINDIR)/$(CONFIG)/grpc_ruby_plugin
 PROTOC_PLUGINS_DIR = $(BINDIR)/$(CONFIG)
@@ -2238,6 +2238,7 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/health/v1/health.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/health/v1/health.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/health/v1/health.pb.cc: src/proto/grpc/health/v1/health.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2253,6 +2254,7 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/lb/v1/load_balancer.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/lb/v1/load_balancer.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/lb/v1/load_balancer.pb.cc: src/proto/grpc/lb/v1/load_balancer.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2268,6 +2270,7 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/reflection/v1alpha/reflection.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/reflection/v1alpha/reflection.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/reflection/v1alpha/reflection.pb.cc: src/proto/grpc/reflection/v1alpha/reflection.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2283,6 +2286,7 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/status/status.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/status/status.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/status/status.pb.cc: src/proto/grpc/status/status.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2298,6 +2302,8 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/compiler_test.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/compiler_test.grpc.pb.cc: protoc_dep_error
 else
+
+
 $(GENDIR)/src/proto/grpc/testing/compiler_test.pb.cc: src/proto/grpc/testing/compiler_test.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2306,13 +2312,14 @@ $(GENDIR)/src/proto/grpc/testing/compiler_test.pb.cc: src/proto/grpc/testing/com
 $(GENDIR)/src/proto/grpc/testing/compiler_test.grpc.pb.cc: src/proto/grpc/testing/compiler_test.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=generate_mock_code=true:$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/control.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/control.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/testing/control.pb.cc: src/proto/grpc/testing/control.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/payloads.pb.cc $(GENDIR)/src/proto/grpc/testing/stats.pb.cc
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2328,6 +2335,7 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc: src/proto/grpc/testing/duplicate/echo_duplicate.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2343,6 +2351,8 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/echo.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc: protoc_dep_error
 else
+
+
 $(GENDIR)/src/proto/grpc/testing/echo.pb.cc: src/proto/grpc/testing/echo.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2351,13 +2361,14 @@ $(GENDIR)/src/proto/grpc/testing/echo.pb.cc: src/proto/grpc/testing/echo.proto $
 $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc: src/proto/grpc/testing/echo.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc
 	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=generate_mock_code=true:$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
 ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc: src/proto/grpc/testing/echo_messages.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2373,6 +2384,7 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/empty.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/empty.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/testing/empty.pb.cc: src/proto/grpc/testing/empty.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2388,6 +2400,7 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/messages.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/messages.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/testing/messages.pb.cc: src/proto/grpc/testing/messages.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2403,6 +2416,7 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/metrics.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/metrics.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/testing/metrics.pb.cc: src/proto/grpc/testing/metrics.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2418,6 +2432,7 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/payloads.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/payloads.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/testing/payloads.pb.cc: src/proto/grpc/testing/payloads.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2433,6 +2448,7 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/services.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/services.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/testing/services.pb.cc: src/proto/grpc/testing/services.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/messages.pb.cc $(GENDIR)/src/proto/grpc/testing/control.pb.cc $(GENDIR)/src/proto/grpc/testing/stats.pb.cc
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2448,6 +2464,7 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/stats.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/stats.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/testing/stats.pb.cc: src/proto/grpc/testing/stats.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
@@ -2463,6 +2480,7 @@ ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/test.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/test.grpc.pb.cc: protoc_dep_error
 else
+
 $(GENDIR)/src/proto/grpc/testing/test.pb.cc: src/proto/grpc/testing/test.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) $(GENDIR)/src/proto/grpc/testing/empty.pb.cc $(GENDIR)/src/proto/grpc/testing/messages.pb.cc
 	$(E) "[PROTOC]  Generating protobuf CC file from $<"
 	$(Q) mkdir -p `dirname $@`
diff --git a/bazel/cc_grpc_library.bzl b/bazel/cc_grpc_library.bzl
index a3996eca0082a0ec44eb7bc4a37a1069a72a2342..0600bb9e304c4f3a92cba88d0a9830d258563e68 100644
--- a/bazel/cc_grpc_library.bzl
+++ b/bazel/cc_grpc_library.bzl
@@ -2,7 +2,7 @@
 
 load("//:bazel/generate_cc.bzl", "generate_cc")
 
-def cc_grpc_library(name, srcs, deps, proto_only, well_known_protos, use_external = False, **kwargs):
+def cc_grpc_library(name, srcs, deps, proto_only, well_known_protos, generate_mock, use_external = False, **kwargs):
   """Generates C++ grpc classes from a .proto file.
 
   Assumes the generated classes will be used in cc_api_version = 2.
@@ -17,6 +17,7 @@ def cc_grpc_library(name, srcs, deps, proto_only, well_known_protos, use_externa
         "@com_google_protobuf//:well_known_protos"
       use_external: When True the grpc deps are prefixed with //external. This
         allows grpc to be used as a dependency in other bazel projects.
+      generate_mock: When true GMOCk code for client stub is generated.
       **kwargs: rest of arguments, e.g., compatible_with and visibility.
   """
   if len(srcs) > 1:
@@ -54,6 +55,7 @@ def cc_grpc_library(name, srcs, deps, proto_only, well_known_protos, use_externa
         srcs = [proto_target],
         plugin = plugin,
         well_known_protos = well_known_protos,
+        generate_mock = generate_mock,
         **kwargs
     )
 
diff --git a/bazel/generate_cc.bzl b/bazel/generate_cc.bzl
index 35c2983b542c2892cdc7b04d645a94b60d21b937..8f0f94f563f7277a98978e3a2d8f7e3a4abc6da6 100644
--- a/bazel/generate_cc.bzl
+++ b/bazel/generate_cc.bzl
@@ -12,6 +12,8 @@ def generate_cc_impl(ctx):
   if ctx.executable.plugin:
     outs += [proto.basename[:-len(".proto")] + ".grpc.pb.h" for proto in protos]
     outs += [proto.basename[:-len(".proto")] + ".grpc.pb.cc" for proto in protos]
+    if ctx.attr.generate_mock:
+      outs += [proto.basename[:-len(".proto")] + "_mock.grpc.pb.h" for proto in protos]
   else:
     outs += [proto.basename[:-len(".proto")] + ".pb.h" for proto in protos]
     outs += [proto.basename[:-len(".proto")] + ".pb.cc" for proto in protos]
@@ -23,7 +25,10 @@ def generate_cc_impl(ctx):
   arguments = []
   if ctx.executable.plugin:
     arguments += ["--plugin=protoc-gen-PLUGIN=" + ctx.executable.plugin.path]
-    arguments += ["--PLUGIN_out=" + ",".join(ctx.attr.flags) + ":" + dir_out]
+    flags = list(ctx.attr.flags)
+    if ctx.attr.generate_mock:
+      flags.append("generate_mock_code=true")
+    arguments += ["--PLUGIN_out=" + ",".join(flags) + ":" + dir_out]
     additional_input = [ctx.executable.plugin]
   else:
     arguments += ["--cpp_out=" + ",".join(ctx.attr.flags) + ":" + dir_out]
@@ -71,6 +76,10 @@ generate_cc = rule(
         "well_known_protos" : attr.label(
             mandatory = False,
         ),
+        "generate_mock" : attr.bool(
+            default = False,
+            mandatory = False,
+        ),
         "_protoc": attr.label(
             default = Label("//external:protocol_compiler"),
             executable = True,
diff --git a/bazel/grpc_build_system.bzl b/bazel/grpc_build_system.bzl
index a438186c75791b9e42bd8f013326a1cbb8c94c8c..a104fa00a0b9d6164fdc4534a71626caa711a428 100644
--- a/bazel/grpc_build_system.bzl
+++ b/bazel/grpc_build_system.bzl
@@ -75,7 +75,7 @@ def grpc_proto_plugin(name, srcs = [], deps = []):
 load("//:bazel/cc_grpc_library.bzl", "cc_grpc_library")
 
 def grpc_proto_library(name, srcs = [], deps = [], well_known_protos = None,
-                       has_services = True, use_external = False):
+                       has_services = True, use_external = False, generate_mock = False):
   cc_grpc_library(
     name = name,
     srcs = srcs,
@@ -83,5 +83,6 @@ def grpc_proto_library(name, srcs = [], deps = [], well_known_protos = None,
     well_known_protos = well_known_protos,
     proto_only = not has_services,
     use_external = use_external,
+    generate_mock = generate_mock,
   )
 
diff --git a/build.yaml b/build.yaml
index d199725470c7f6ddcbbf4ea7787f3bddeacf6b11..80ad5498f163bedad556869d615aae608d4f6017 100644
--- a/build.yaml
+++ b/build.yaml
@@ -971,6 +971,7 @@ filegroups:
 - name: grpc++_test
   language: c++
   public_headers:
+  - include/grpc++/test/mock_stream.h
   - include/grpc++/test/server_context_test_spouse.h
   deps:
   - grpc++
@@ -3693,7 +3694,7 @@ targets:
   - grpc
   - gpr
   args:
-  - --generated_file_path=gens/src/proto/grpc/testing/compiler_test.grpc.pb.h
+  - --generated_file_path=gens/src/proto/grpc/testing/
 - name: grpc_cli
   build: test
   run: false
@@ -3954,6 +3955,8 @@ targets:
   gtest: true
   build: test
   language: c++
+  headers:
+  - include/grpc++/test/mock_stream.h
   src:
   - test/cpp/end2end/mock_test.cc
   deps:
@@ -4466,7 +4469,7 @@ configs:
     CPPFLAGS: -O0 -fsanitize-coverage=edge -fsanitize=undefined -fno-omit-frame-pointer
       -Wno-unused-command-line-argument -Wvarargs
     CXX: clang++
-    DEFINES: NDEBUG
+    DEFINES: NDEBUG GRPC_UBSAN
     LD: clang
     LDFLAGS: -fsanitize=undefined,unsigned-integer-overflow
     LDXX: clang++
diff --git a/include/grpc++/test/mock_stream.h b/include/grpc++/test/mock_stream.h
new file mode 100644
index 0000000000000000000000000000000000000000..f2de9472d6b957d0ef902da2ff44001e6cd473ff
--- /dev/null
+++ b/include/grpc++/test/mock_stream.h
@@ -0,0 +1,163 @@
+/*
+ *
+ * Copyright 2017, 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.
+ *
+ */
+
+#ifndef GRPCXX_TEST_MOCK_STREAM_H
+#define GRPCXX_TEST_MOCK_STREAM_H
+
+#include <stdint.h>
+
+#include <gmock/gmock.h>
+#include <grpc++/impl/codegen/call.h>
+#include <grpc++/support/async_stream.h>
+#include <grpc++/support/async_unary_call.h>
+#include <grpc++/support/sync_stream.h>
+
+namespace grpc {
+namespace testing {
+
+template <class R>
+class MockClientReader : public ClientReaderInterface<R> {
+ public:
+  MockClientReader() = default;
+
+  // ClientStreamingInterface
+  MOCK_METHOD0_T(Finish, Status());
+
+  // ReaderInterface
+  MOCK_METHOD1_T(NextMessageSize, bool(uint32_t*));
+  MOCK_METHOD1_T(Read, bool(R*));
+
+  // ClientReaderInterface
+  MOCK_METHOD0_T(WaitForInitialMetadata, void());
+};
+
+template <class W>
+class MockClientWriter : public ClientWriterInterface<W> {
+ public:
+  MockClientWriter() = default;
+
+  // ClientStreamingInterface
+  MOCK_METHOD0_T(Finish, Status());
+
+  // WriterInterface
+  MOCK_METHOD2_T(Write, bool(const W&, const WriteOptions));
+
+  // ClientWriterInterface
+  MOCK_METHOD0_T(WritesDone, bool());
+};
+
+template <class W, class R>
+class MockClientReaderWriter : public ClientReaderWriterInterface<W, R> {
+ public:
+  MockClientReaderWriter() = default;
+
+  // ClientStreamingInterface
+  MOCK_METHOD0_T(Finish, Status());
+
+  // ReaderInterface
+  MOCK_METHOD1_T(NextMessageSize, bool(uint32_t*));
+  MOCK_METHOD1_T(Read, bool(R*));
+
+  // WriterInterface
+  MOCK_METHOD2_T(Write, bool(const W&, const WriteOptions));
+
+  // ClientReaderWriterInterface
+  MOCK_METHOD0_T(WaitForInitialMetadata, void());
+  MOCK_METHOD0_T(WritesDone, bool());
+};
+
+// TODO: We do not support mocking an async RPC for now.
+
+template <class R>
+class MockClientAsyncResponseReader
+    : public ClientAsyncResponseReaderInterface<R> {
+ public:
+  MockClientAsyncResponseReader() = default;
+
+  MOCK_METHOD1_T(ReadInitialMetadata, void(void*));
+  MOCK_METHOD3_T(Finish, void(R*, Status*, void*));
+};
+
+template <class R>
+class MockClientAsyncReader : public ClientAsyncReaderInterface<R> {
+ public:
+  MockClientAsyncReader() = default;
+
+  // ClientAsyncStreamingInterface
+  MOCK_METHOD1_T(ReadInitialMetadata, void(void*));
+  MOCK_METHOD2_T(Finish, void(Status*, void*));
+
+  // AsyncReaderInterface
+  MOCK_METHOD2_T(Read, void(R*, void*));
+};
+
+template <class W>
+class MockClientAsyncWriter : public ClientAsyncWriterInterface<W> {
+ public:
+  MockClientAsyncWriter() = default;
+
+  // ClientAsyncStreamingInterface
+  MOCK_METHOD1_T(ReadInitialMetadata, void(void*));
+  MOCK_METHOD2_T(Finish, void(Status*, void*));
+
+  // AsyncWriterInterface
+  MOCK_METHOD2_T(Write, void(const W&, void*));
+
+  // ClientAsyncWriterInterface
+  MOCK_METHOD1_T(WritesDone, void(void*));
+};
+
+template <class W, class R>
+class MockClientAsyncReaderWriter
+    : public ClientAsyncReaderWriterInterface<W, R> {
+ public:
+  MockClientAsyncReaderWriter() = default;
+
+  // ClientAsyncStreamingInterface
+  MOCK_METHOD1_T(ReadInitialMetadata, void(void*));
+  MOCK_METHOD2_T(Finish, void(Status*, void*));
+
+  // AsyncWriterInterface
+  MOCK_METHOD2_T(Write, void(const W&, void*));
+
+  // AsyncReaderInterface
+  MOCK_METHOD2_T(Read, void(R*, void*));
+
+  // ClientAsyncReaderWriterInterface
+  MOCK_METHOD1_T(WritesDone, void(void*));
+};
+
+}  // namespace testing
+}  // namespace grpc
+
+#endif  // GRPCXX_TEST_MOCK_STREAM_H
diff --git a/src/compiler/cpp_generator.cc b/src/compiler/cpp_generator.cc
index 4cc6a4cf39375cc5e9f8bec178897c7c0b739f65..d3e71625d6556a2167804335f554d1326a762e57 100644
--- a/src/compiler/cpp_generator.cc
+++ b/src/compiler/cpp_generator.cc
@@ -1408,4 +1408,180 @@ grpc::string GetSourceEpilogue(grpc_generator::File *file,
   return temp;
 }
 
+// TODO(mmukhi): Make sure we need parameters or not.
+grpc::string GetMockPrologue(grpc_generator::File *file,
+                             const Parameters & /*params*/) {
+  grpc::string output;
+  {
+    // Scope the output stream so it closes and finalizes output to the string.
+    auto printer = file->CreatePrinter(&output);
+    std::map<grpc::string, grpc::string> vars;
+
+    vars["filename"] = file->filename();
+    vars["filename_base"] = file->filename_without_ext();
+    vars["message_header_ext"] = message_header_ext();
+    vars["service_header_ext"] = service_header_ext();
+
+    printer->Print(vars, "// Generated by the gRPC C++ plugin.\n");
+    printer->Print(vars,
+                   "// If you make any local change, they will be lost.\n");
+    printer->Print(vars, "// source: $filename$\n\n");
+
+    printer->Print(vars, "#include \"$filename_base$$message_header_ext$\"\n");
+    printer->Print(vars, "#include \"$filename_base$$service_header_ext$\"\n");
+    printer->Print(vars, file->additional_headers().c_str());
+    printer->Print(vars, "\n");
+  }
+  return output;
+}
+
+// TODO(mmukhi): Add client-stream and completion-queue headers.
+grpc::string GetMockIncludes(grpc_generator::File *file,
+                             const Parameters &params) {
+  grpc::string output;
+  {
+    // Scope the output stream so it closes and finalizes output to the string.
+    auto printer = file->CreatePrinter(&output);
+    std::map<grpc::string, grpc::string> vars;
+
+    static const char *headers_strs[] = {
+        "grpc++/impl/codegen/async_stream.h",
+        "grpc++/impl/codegen/sync_stream.h", "gmock/gmock.h",
+    };
+    std::vector<grpc::string> headers(headers_strs, array_end(headers_strs));
+    PrintIncludes(printer.get(), headers, params);
+
+    if (!file->package().empty()) {
+      std::vector<grpc::string> parts = file->package_parts();
+
+      for (auto part = parts.begin(); part != parts.end(); part++) {
+        vars["part"] = *part;
+        printer->Print(vars, "namespace $part$ {\n");
+      }
+    }
+
+    printer->Print(vars, "\n");
+  }
+  return output;
+}
+
+void PrintMockClientMethods(grpc_generator::Printer *printer,
+                            const grpc_generator::Method *method,
+                            std::map<grpc::string, grpc::string> *vars) {
+  (*vars)["Method"] = method->name();
+  (*vars)["Request"] = method->input_type_name();
+  (*vars)["Response"] = method->output_type_name();
+
+  if (method->NoStreaming()) {
+    printer->Print(
+        *vars,
+        "MOCK_METHOD3($Method$, ::grpc::Status(::grpc::ClientContext* context, "
+        "const $Request$& request, $Response$* response));\n");
+    printer->Print(*vars,
+                   "MOCK_METHOD3(Async$Method$Raw, "
+                   "::grpc::ClientAsyncResponseReaderInterface< $Response$>*"
+                   "(::grpc::ClientContext* context, const $Request$& request, "
+                   "::grpc::CompletionQueue* cq));\n");
+  } else if (ClientOnlyStreaming(method)) {
+    printer->Print(
+        *vars,
+        "MOCK_METHOD2($Method$Raw, "
+        "::grpc::ClientWriterInterface< $Request$>*"
+        "(::grpc::ClientContext* context, $Response$* response));\n");
+    printer->Print(*vars,
+                   "MOCK_METHOD4(Async$Method$Raw, "
+                   "::grpc::ClientAsyncWriterInterface< $Request$>*"
+                   "(::grpc::ClientContext* context, $Response$* response, "
+                   "::grpc::CompletionQueue* cq, void* tag));\n");
+  } else if (ServerOnlyStreaming(method)) {
+    printer->Print(
+        *vars,
+        "MOCK_METHOD2($Method$Raw, "
+        "::grpc::ClientReaderInterface< $Response$>*"
+        "(::grpc::ClientContext* context, const $Request$& request));\n");
+    printer->Print(*vars,
+                   "MOCK_METHOD4(Async$Method$Raw, "
+                   "::grpc::ClientAsyncReaderInterface< $Response$>*"
+                   "(::grpc::ClientContext* context, const $Request$& request, "
+                   "::grpc::CompletionQueue* cq, void* tag));\n");
+  } else if (method->BidiStreaming()) {
+    printer->Print(
+        *vars,
+        "MOCK_METHOD1($Method$Raw, "
+        "::grpc::ClientReaderWriterInterface< $Request$, $Response$>*"
+        "(::grpc::ClientContext* context));\n");
+    printer->Print(
+        *vars,
+        "MOCK_METHOD3(Async$Method$Raw, "
+        "::grpc::ClientAsyncReaderWriterInterface<$Request$, $Response$>*"
+        "(::grpc::ClientContext* context, ::grpc::CompletionQueue* cq, "
+        "void* tag));\n");
+  }
+}
+
+void PrintMockService(grpc_generator::Printer *printer,
+                      const grpc_generator::Service *service,
+                      std::map<grpc::string, grpc::string> *vars) {
+  (*vars)["Service"] = service->name();
+
+  printer->Print(*vars,
+                 "class Mock$Service$Stub : public $Service$::StubInterface {\n"
+                 " public:\n");
+  printer->Indent();
+  for (int i = 0; i < service->method_count(); ++i) {
+    PrintMockClientMethods(printer, service->method(i).get(), vars);
+  }
+  printer->Outdent();
+  printer->Print("};\n");
+}
+
+grpc::string GetMockServices(grpc_generator::File *file,
+                             const Parameters &params) {
+  grpc::string output;
+  {
+    // Scope the output stream so it closes and finalizes output to the string.
+    auto printer = file->CreatePrinter(&output);
+    std::map<grpc::string, grpc::string> vars;
+    // Package string is empty or ends with a dot. It is used to fully qualify
+    // method names.
+    vars["Package"] = file->package();
+    if (!file->package().empty()) {
+      vars["Package"].append(".");
+    }
+
+    if (!params.services_namespace.empty()) {
+      vars["services_namespace"] = params.services_namespace;
+      printer->Print(vars, "\nnamespace $services_namespace$ {\n\n");
+    }
+
+    for (int i = 0; i < file->service_count(); i++) {
+      PrintMockService(printer.get(), file->service(i).get(), &vars);
+      printer->Print("\n");
+    }
+
+    if (!params.services_namespace.empty()) {
+      printer->Print(vars, "} // namespace $services_namespace$\n\n");
+    }
+  }
+  return output;
+}
+
+grpc::string GetMockEpilogue(grpc_generator::File *file,
+                             const Parameters & /*params*/) {
+  grpc::string temp;
+
+  if (!file->package().empty()) {
+    std::vector<grpc::string> parts = file->package_parts();
+
+    for (auto part = parts.begin(); part != parts.end(); part++) {
+      temp.append("} // namespace ");
+      temp.append(*part);
+      temp.append("\n");
+    }
+    temp.append("\n");
+  }
+
+  return temp;
+}
+
 }  // namespace grpc_cpp_generator
diff --git a/src/compiler/cpp_generator.h b/src/compiler/cpp_generator.h
index 69fd8a93e93a971dfb56b42c0e690f399bf448ce..6119ebe2896c9a9065a39a286b1d32440a4a7ac9 100644
--- a/src/compiler/cpp_generator.h
+++ b/src/compiler/cpp_generator.h
@@ -65,6 +65,8 @@ struct Parameters {
   bool use_system_headers;
   // Prefix to any grpc include
   grpc::string grpc_search_path;
+  // Generate GMOCK code to facilitate unit testing.
+  bool generate_mock_code;
 };
 
 // Return the prologue of the generated header file.
@@ -99,6 +101,38 @@ grpc::string GetSourceServices(grpc_generator::File *file,
 grpc::string GetSourceEpilogue(grpc_generator::File *file,
                                const Parameters &params);
 
+// Return the prologue of the generated mock file.
+grpc::string GetMockPrologue(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the includes needed for generated mock file.
+grpc::string GetMockIncludes(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the services for generated mock file.
+grpc::string GetMockServices(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the epilogue of generated mock file.
+grpc::string GetMockEpilogue(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the prologue of the generated mock file.
+grpc::string GetMockPrologue(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the includes needed for generated mock file.
+grpc::string GetMockIncludes(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the services for generated mock file.
+grpc::string GetMockServices(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the epilogue of generated mock file.
+grpc::string GetMockEpilogue(grpc_generator::File *file,
+                             const Parameters &params);
+
 }  // namespace grpc_cpp_generator
 
 #endif  // GRPC_INTERNAL_COMPILER_CPP_GENERATOR_H
diff --git a/src/compiler/cpp_plugin.cc b/src/compiler/cpp_plugin.cc
index 4ee05ee03703fe36190096908f7dd170fa43ebbb..35f1bf3e93c8c11bb72087d08973d7d0e9ffe2eb 100644
--- a/src/compiler/cpp_plugin.cc
+++ b/src/compiler/cpp_plugin.cc
@@ -62,6 +62,7 @@ class CppGrpcGenerator : public grpc::protobuf::compiler::CodeGenerator {
 
     grpc_cpp_generator::Parameters generator_parameters;
     generator_parameters.use_system_headers = true;
+    generator_parameters.generate_mock_code = false;
 
     ProtoBufFile pbfile(file);
 
@@ -85,6 +86,13 @@ class CppGrpcGenerator : public grpc::protobuf::compiler::CodeGenerator {
           }
         } else if (param[0] == "grpc_search_path") {
           generator_parameters.grpc_search_path = param[1];
+        } else if (param[0] == "generate_mock_code") {
+          if (param[1] == "true") {
+            generator_parameters.generate_mock_code = true;
+          } else if (param[1] != "false") {
+            *error = grpc::string("Invalid parameter: ") + *parameter_string;
+            return false;
+          }
         } else {
           *error = grpc::string("Unknown parameter: ") + *parameter_string;
           return false;
@@ -114,6 +122,19 @@ class CppGrpcGenerator : public grpc::protobuf::compiler::CodeGenerator {
     grpc::protobuf::io::CodedOutputStream source_coded_out(source_output.get());
     source_coded_out.WriteRaw(source_code.data(), source_code.size());
 
+    if (!generator_parameters.generate_mock_code) {
+      return true;
+    }
+    grpc::string mock_code =
+        grpc_cpp_generator::GetMockPrologue(&pbfile, generator_parameters) +
+        grpc_cpp_generator::GetMockIncludes(&pbfile, generator_parameters) +
+        grpc_cpp_generator::GetMockServices(&pbfile, generator_parameters) +
+        grpc_cpp_generator::GetMockEpilogue(&pbfile, generator_parameters);
+    std::unique_ptr<grpc::protobuf::io::ZeroCopyOutputStream> mock_output(
+        context->Open(file_name + "_mock.grpc.pb.h"));
+    grpc::protobuf::io::CodedOutputStream mock_coded_out(mock_output.get());
+    mock_coded_out.WriteRaw(mock_code.data(), mock_code.size());
+
     return true;
   }
 
diff --git a/src/core/lib/iomgr/udp_server.c b/src/core/lib/iomgr/udp_server.c
index ca283d034f93e8ec4a1f101aa399300ff2a3d8ab..af70746064e476203c74dec3900c8a632252c6d2 100644
--- a/src/core/lib/iomgr/udp_server.c
+++ b/src/core/lib/iomgr/udp_server.c
@@ -92,6 +92,11 @@ struct grpc_udp_listener {
   struct grpc_udp_listener *next;
 };
 
+struct shutdown_fd_args {
+  grpc_fd *fd;
+  gpr_mu *server_mu;
+};
+
 /* the overall server */
 struct grpc_udp_server {
   gpr_mu mu;
@@ -151,8 +156,13 @@ grpc_udp_server *grpc_udp_server_create(const grpc_channel_args *args) {
   return s;
 }
 
-static void shutdown_fd(grpc_exec_ctx *exec_ctx, void *fd, grpc_error *error) {
-  grpc_fd_shutdown(exec_ctx, (grpc_fd *)fd, GRPC_ERROR_REF(error));
+static void shutdown_fd(grpc_exec_ctx *exec_ctx, void *args,
+                        grpc_error *error) {
+  struct shutdown_fd_args *shutdown_args = (struct shutdown_fd_args *)args;
+  gpr_mu_lock(shutdown_args->server_mu);
+  grpc_fd_shutdown(exec_ctx, shutdown_args->fd, GRPC_ERROR_REF(error));
+  gpr_mu_unlock(shutdown_args->server_mu);
+  gpr_free(shutdown_args);
 }
 
 static void dummy_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
@@ -242,7 +252,10 @@ void grpc_udp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_udp_server *s,
   if (s->active_ports) {
     for (sp = s->head; sp; sp = sp->next) {
       GPR_ASSERT(sp->orphan_cb);
-      grpc_closure_init(&sp->orphan_fd_closure, shutdown_fd, sp->emfd,
+      struct shutdown_fd_args *args = gpr_malloc(sizeof(*args));
+      args->fd = sp->emfd;
+      args->server_mu = &s->mu;
+      grpc_closure_init(&sp->orphan_fd_closure, shutdown_fd, args,
                         grpc_schedule_on_exec_ctx);
       sp->orphan_cb(exec_ctx, sp->emfd, &sp->orphan_fd_closure,
                     sp->server->user_data);
diff --git a/src/proto/grpc/testing/BUILD b/src/proto/grpc/testing/BUILD
index 6f3422e4d167a89c50a1c5ae6e1779122fee1ba5..805988c3372efe113333df9fdc326fdf106754b6 100644
--- a/src/proto/grpc/testing/BUILD
+++ b/src/proto/grpc/testing/BUILD
@@ -36,6 +36,7 @@ load("//bazel:grpc_build_system.bzl", "grpc_proto_library")
 grpc_proto_library(
     name = "compiler_test_proto",
     srcs = ["compiler_test.proto"],
+    generate_mock = True,
 )
 
 grpc_proto_library(
@@ -55,6 +56,7 @@ grpc_proto_library(
     name = "echo_proto",
     srcs = ["echo.proto"],
     deps = ["echo_messages_proto"],
+    generate_mock = True,
 )
 
 grpc_proto_library(
diff --git a/src/proto/grpc/testing/compiler_test.proto b/src/proto/grpc/testing/compiler_test.proto
index 085e8ae59f7933903f271686dc4c55cc51a8ce30..24735522e03c97c4211216495a96c46365f28e45 100644
--- a/src/proto/grpc/testing/compiler_test.proto
+++ b/src/proto/grpc/testing/compiler_test.proto
@@ -59,6 +59,14 @@ service ServiceA {
   // Method A2 leading comment 2
   rpc MethodA2(stream Request) returns (Response);
   // MethodA2 trailing comment 1
+
+  // Method A3 leading comment 1
+  rpc MethodA3(Request) returns (stream Response);
+  // Method A3 trailing comment 1
+
+  // Method A4 leading comment 1
+  rpc MethodA4(stream Request) returns (stream Response);
+  // Method A4 trailing comment 1
 }
 // Ignored ServiceA trailing comment 1
 
diff --git a/templates/Makefile.template b/templates/Makefile.template
index 1e6ca9337d732a9f6575d8788dbd806ff15dc155..5ce606f8280145c3c1832777d628d78af89e4504 100644
--- a/templates/Makefile.template
+++ b/templates/Makefile.template
@@ -311,7 +311,7 @@
   USE_BUILT_PROTOC = false
   endif
 
-  GTEST_LIB = -Ithird_party/googletest/googletest/include -Ithird_party/googletest/googletest third_party/googletest/googletest/src/gtest-all.cc
+  GTEST_LIB = -Ithird_party/googletest/googletest/include -Ithird_party/googletest/googletest third_party/googletest/googletest/src/gtest-all.cc -Ithird_party/googletest/googlemock/include -Ithird_party/googletest/googlemock third_party/googletest/googlemock/src/gmock-all.cc
   GTEST_LIB += -lgflags
   ifeq ($(V),1)
   E = @:
@@ -716,7 +716,7 @@
   PC_REQUIRES_GRPCXX =
   PC_LIBS_GRPCXX =
 
-  CPPFLAGS := -Ithird_party/googletest/googletest/include $(CPPFLAGS)
+  CPPFLAGS := -Ithird_party/googletest/googletest/include -Ithird_party/googletest/googlemock/include $(CPPFLAGS)
 
   PROTOC_PLUGINS_ALL =\
   % for tgt in targets:
@@ -1240,6 +1240,14 @@
   $(GENDIR)/${p}.pb.cc: protoc_dep_error
   $(GENDIR)/${p}.grpc.pb.cc: protoc_dep_error
   else
+  <%
+    pluginflags=""
+  %>
+  % if p in ["src/proto/grpc/testing/compiler_test", "src/proto/grpc/testing/echo"]:
+  <%
+    pluginflags="generate_mock_code=true:"
+  %>
+  % endif
   $(GENDIR)/${p}.pb.cc: ${p}.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) ${' '.join('$(GENDIR)/%s.pb.cc' % q for q in proto_deps.get(p, []))}
   	$(E) "[PROTOC]  Generating protobuf CC file from $<"
   	$(Q) mkdir -p `dirname $@`
@@ -1248,7 +1256,7 @@
   $(GENDIR)/${p}.grpc.pb.cc: ${p}.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) ${' '.join('$(GENDIR)/%s.pb.cc $(GENDIR)/%s.grpc.pb.cc' % (q,q) for q in proto_deps.get(p, []))}
   	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
   	$(Q) mkdir -p `dirname $@`
-  	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+  	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=${pluginflags}$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
   endif
 
   % endfor
diff --git a/templates/tools/run_tests/generated/sources_and_headers.json.template b/templates/tools/run_tests/generated/sources_and_headers.json.template
index 1c5c9747d65ce7a69190c78135d26faaf00bd65c..c7dc3c837d14f8542bb288bfc5e1c2f7cc436821 100644
--- a/templates/tools/run_tests/generated/sources_and_headers.json.template
+++ b/templates/tools/run_tests/generated/sources_and_headers.json.template
@@ -9,7 +9,7 @@
     for f in src:
       name, ext = os.path.splitext(f)
       if ext == '.proto':
-        out.extend(fmt % name for fmt in ['%s.grpc.pb.h', '%s.pb.h'])
+        out.extend(fmt % name for fmt in ['%s.grpc.pb.h', '%s.pb.h', '%s_mock.grpc.pb.h'])
     return out
 
   def all_targets(targets, libs, filegroups):
diff --git a/test/core/util/test_config.c b/test/core/util/test_config.c
index 0180d6f08d446b5d83f40ea69fbc8421d8608bb8..9a400c54ca22f928b585f025b76aa3218f1343e9 100644
--- a/test/core/util/test_config.c
+++ b/test/core/util/test_config.c
@@ -348,6 +348,14 @@ bool BuiltUnderMsan() {
 #endif
 }
 
+bool BuiltUnderUbsan() {
+#ifdef GRPC_UBSAN
+  return true;
+#else
+  return false;
+#endif
+}
+
 int64_t grpc_test_sanitizer_slowdown_factor() {
   int64_t sanitizer_multiplier = 1;
   if (BuiltUnderValgrind()) {
@@ -358,6 +366,8 @@ int64_t grpc_test_sanitizer_slowdown_factor() {
     sanitizer_multiplier = 3;
   } else if (BuiltUnderMsan()) {
     sanitizer_multiplier = 4;
+  } else if (BuiltUnderUbsan()) {
+    sanitizer_multiplier = 5;
   }
   return sanitizer_multiplier;
 }
diff --git a/test/cpp/codegen/BUILD b/test/cpp/codegen/BUILD
index 14d5733da2c8181ce641a2928f56a0e433df07c8..43d133fc342fe966b422f8f4b73b54e8bb859ab4 100644
--- a/test/cpp/codegen/BUILD
+++ b/test/cpp/codegen/BUILD
@@ -62,7 +62,7 @@ cc_test(
 cc_test(
     name = "golden_file_test",
     srcs = ["golden_file_test.cc"],
-    args = ["--generated_file_path=$(GENDIR)/src/proto/grpc/testing/compiler_test.grpc.pb.h"],
+    args = ["--generated_file_path=$(GENDIR)/src/proto/grpc/testing/"],
     data = [
         ":compiler_test_golden",
         "//src/proto/grpc/testing:_compiler_test_proto_grpc_codegen",
diff --git a/test/cpp/codegen/compiler_test_golden b/test/cpp/codegen/compiler_test_golden
index fd26a17ac1183077d1d5ad1140674f83f4508080..8e3ae32a4946a7785fe17d586ff2bf481cf151c1 100644
--- a/test/cpp/codegen/compiler_test_golden
+++ b/test/cpp/codegen/compiler_test_golden
@@ -89,10 +89,30 @@ class ServiceA final {
       return std::unique_ptr< ::grpc::ClientAsyncWriterInterface< ::grpc::testing::Request>>(AsyncMethodA2Raw(context, response, cq, tag));
     }
     // MethodA2 trailing comment 1
+    // Method A3 leading comment 1
+    std::unique_ptr< ::grpc::ClientReaderInterface< ::grpc::testing::Response>> MethodA3(::grpc::ClientContext* context, const ::grpc::testing::Request& request) {
+      return std::unique_ptr< ::grpc::ClientReaderInterface< ::grpc::testing::Response>>(MethodA3Raw(context, request));
+    }
+    std::unique_ptr< ::grpc::ClientAsyncReaderInterface< ::grpc::testing::Response>> AsyncMethodA3(::grpc::ClientContext* context, const ::grpc::testing::Request& request, ::grpc::CompletionQueue* cq, void* tag) {
+      return std::unique_ptr< ::grpc::ClientAsyncReaderInterface< ::grpc::testing::Response>>(AsyncMethodA3Raw(context, request, cq, tag));
+    }
+    // Method A3 trailing comment 1
+    // Method A4 leading comment 1
+    std::unique_ptr< ::grpc::ClientReaderWriterInterface< ::grpc::testing::Request, ::grpc::testing::Response>> MethodA4(::grpc::ClientContext* context) {
+      return std::unique_ptr< ::grpc::ClientReaderWriterInterface< ::grpc::testing::Request, ::grpc::testing::Response>>(MethodA4Raw(context));
+    }
+    std::unique_ptr< ::grpc::ClientAsyncReaderWriterInterface< ::grpc::testing::Request, ::grpc::testing::Response>> AsyncMethodA4(::grpc::ClientContext* context, ::grpc::CompletionQueue* cq, void* tag) {
+      return std::unique_ptr< ::grpc::ClientAsyncReaderWriterInterface< ::grpc::testing::Request, ::grpc::testing::Response>>(AsyncMethodA4Raw(context, cq, tag));
+    }
+    // Method A4 trailing comment 1
   private:
     virtual ::grpc::ClientAsyncResponseReaderInterface< ::grpc::testing::Response>* AsyncMethodA1Raw(::grpc::ClientContext* context, const ::grpc::testing::Request& request, ::grpc::CompletionQueue* cq) = 0;
     virtual ::grpc::ClientWriterInterface< ::grpc::testing::Request>* MethodA2Raw(::grpc::ClientContext* context, ::grpc::testing::Response* response) = 0;
     virtual ::grpc::ClientAsyncWriterInterface< ::grpc::testing::Request>* AsyncMethodA2Raw(::grpc::ClientContext* context, ::grpc::testing::Response* response, ::grpc::CompletionQueue* cq, void* tag) = 0;
+    virtual ::grpc::ClientReaderInterface< ::grpc::testing::Response>* MethodA3Raw(::grpc::ClientContext* context, const ::grpc::testing::Request& request) = 0;
+    virtual ::grpc::ClientAsyncReaderInterface< ::grpc::testing::Response>* AsyncMethodA3Raw(::grpc::ClientContext* context, const ::grpc::testing::Request& request, ::grpc::CompletionQueue* cq, void* tag) = 0;
+    virtual ::grpc::ClientReaderWriterInterface< ::grpc::testing::Request, ::grpc::testing::Response>* MethodA4Raw(::grpc::ClientContext* context) = 0;
+    virtual ::grpc::ClientAsyncReaderWriterInterface< ::grpc::testing::Request, ::grpc::testing::Response>* AsyncMethodA4Raw(::grpc::ClientContext* context, ::grpc::CompletionQueue* cq, void* tag) = 0;
   };
   class Stub final : public StubInterface {
    public:
@@ -107,14 +127,32 @@ class ServiceA final {
     std::unique_ptr< ::grpc::ClientAsyncWriter< ::grpc::testing::Request>> AsyncMethodA2(::grpc::ClientContext* context, ::grpc::testing::Response* response, ::grpc::CompletionQueue* cq, void* tag) {
       return std::unique_ptr< ::grpc::ClientAsyncWriter< ::grpc::testing::Request>>(AsyncMethodA2Raw(context, response, cq, tag));
     }
+    std::unique_ptr< ::grpc::ClientReader< ::grpc::testing::Response>> MethodA3(::grpc::ClientContext* context, const ::grpc::testing::Request& request) {
+      return std::unique_ptr< ::grpc::ClientReader< ::grpc::testing::Response>>(MethodA3Raw(context, request));
+    }
+    std::unique_ptr< ::grpc::ClientAsyncReader< ::grpc::testing::Response>> AsyncMethodA3(::grpc::ClientContext* context, const ::grpc::testing::Request& request, ::grpc::CompletionQueue* cq, void* tag) {
+      return std::unique_ptr< ::grpc::ClientAsyncReader< ::grpc::testing::Response>>(AsyncMethodA3Raw(context, request, cq, tag));
+    }
+    std::unique_ptr< ::grpc::ClientReaderWriter< ::grpc::testing::Request, ::grpc::testing::Response>> MethodA4(::grpc::ClientContext* context) {
+      return std::unique_ptr< ::grpc::ClientReaderWriter< ::grpc::testing::Request, ::grpc::testing::Response>>(MethodA4Raw(context));
+    }
+    std::unique_ptr<  ::grpc::ClientAsyncReaderWriter< ::grpc::testing::Request, ::grpc::testing::Response>> AsyncMethodA4(::grpc::ClientContext* context, ::grpc::CompletionQueue* cq, void* tag) {
+      return std::unique_ptr< ::grpc::ClientAsyncReaderWriter< ::grpc::testing::Request, ::grpc::testing::Response>>(AsyncMethodA4Raw(context, cq, tag));
+    }
 
    private:
     std::shared_ptr< ::grpc::ChannelInterface> channel_;
     ::grpc::ClientAsyncResponseReader< ::grpc::testing::Response>* AsyncMethodA1Raw(::grpc::ClientContext* context, const ::grpc::testing::Request& request, ::grpc::CompletionQueue* cq) override;
     ::grpc::ClientWriter< ::grpc::testing::Request>* MethodA2Raw(::grpc::ClientContext* context, ::grpc::testing::Response* response) override;
     ::grpc::ClientAsyncWriter< ::grpc::testing::Request>* AsyncMethodA2Raw(::grpc::ClientContext* context, ::grpc::testing::Response* response, ::grpc::CompletionQueue* cq, void* tag) override;
+    ::grpc::ClientReader< ::grpc::testing::Response>* MethodA3Raw(::grpc::ClientContext* context, const ::grpc::testing::Request& request) override;
+    ::grpc::ClientAsyncReader< ::grpc::testing::Response>* AsyncMethodA3Raw(::grpc::ClientContext* context, const ::grpc::testing::Request& request, ::grpc::CompletionQueue* cq, void* tag) override;
+    ::grpc::ClientReaderWriter< ::grpc::testing::Request, ::grpc::testing::Response>* MethodA4Raw(::grpc::ClientContext* context) override;
+    ::grpc::ClientAsyncReaderWriter< ::grpc::testing::Request, ::grpc::testing::Response>* AsyncMethodA4Raw(::grpc::ClientContext* context, ::grpc::CompletionQueue* cq, void* tag) override;
     const ::grpc::RpcMethod rpcmethod_MethodA1_;
     const ::grpc::RpcMethod rpcmethod_MethodA2_;
+    const ::grpc::RpcMethod rpcmethod_MethodA3_;
+    const ::grpc::RpcMethod rpcmethod_MethodA4_;
   };
   static std::unique_ptr<Stub> NewStub(const std::shared_ptr< ::grpc::ChannelInterface>& channel, const ::grpc::StubOptions& options = ::grpc::StubOptions());
 
@@ -131,6 +169,12 @@ class ServiceA final {
     // Method A2 leading comment 2
     virtual ::grpc::Status MethodA2(::grpc::ServerContext* context, ::grpc::ServerReader< ::grpc::testing::Request>* reader, ::grpc::testing::Response* response);
     // MethodA2 trailing comment 1
+    // Method A3 leading comment 1
+    virtual ::grpc::Status MethodA3(::grpc::ServerContext* context, const ::grpc::testing::Request* request, ::grpc::ServerWriter< ::grpc::testing::Response>* writer);
+    // Method A3 trailing comment 1
+    // Method A4 leading comment 1
+    virtual ::grpc::Status MethodA4(::grpc::ServerContext* context, ::grpc::ServerReaderWriter< ::grpc::testing::Response, ::grpc::testing::Request>* stream);
+    // Method A4 trailing comment 1
   };
   template <class BaseClass>
   class WithAsyncMethod_MethodA1 : public BaseClass {
@@ -172,7 +216,47 @@ class ServiceA final {
       ::grpc::Service::RequestAsyncClientStreaming(1, context, reader, new_call_cq, notification_cq, tag);
     }
   };
-  typedef WithAsyncMethod_MethodA1<WithAsyncMethod_MethodA2<Service > > AsyncService;
+  template <class BaseClass>
+  class WithAsyncMethod_MethodA3 : public BaseClass {
+   private:
+    void BaseClassMustBeDerivedFromService(const Service *service) {}
+   public:
+    WithAsyncMethod_MethodA3() {
+      ::grpc::Service::MarkMethodAsync(2);
+    }
+    ~WithAsyncMethod_MethodA3() override {
+      BaseClassMustBeDerivedFromService(this);
+    }
+    // disable synchronous version of this method
+    ::grpc::Status MethodA3(::grpc::ServerContext* context, const ::grpc::testing::Request* request, ::grpc::ServerWriter< ::grpc::testing::Response>* writer) final override {
+      abort();
+      return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
+    }
+    void RequestMethodA3(::grpc::ServerContext* context, ::grpc::testing::Request* request, ::grpc::ServerAsyncWriter< ::grpc::testing::Response>* writer, ::grpc::CompletionQueue* new_call_cq, ::grpc::ServerCompletionQueue* notification_cq, void *tag) {
+      ::grpc::Service::RequestAsyncServerStreaming(2, context, request, writer, new_call_cq, notification_cq, tag);
+    }
+  };
+  template <class BaseClass>
+  class WithAsyncMethod_MethodA4 : public BaseClass {
+   private:
+    void BaseClassMustBeDerivedFromService(const Service *service) {}
+   public:
+    WithAsyncMethod_MethodA4() {
+      ::grpc::Service::MarkMethodAsync(3);
+    }
+    ~WithAsyncMethod_MethodA4() override {
+      BaseClassMustBeDerivedFromService(this);
+    }
+    // disable synchronous version of this method
+    ::grpc::Status MethodA4(::grpc::ServerContext* context, ::grpc::ServerReaderWriter< ::grpc::testing::Response, ::grpc::testing::Request>* stream) final override {
+      abort();
+      return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
+    }
+    void RequestMethodA4(::grpc::ServerContext* context, ::grpc::ServerAsyncReaderWriter< ::grpc::testing::Response, ::grpc::testing::Request>* stream, ::grpc::CompletionQueue* new_call_cq, ::grpc::ServerCompletionQueue* notification_cq, void *tag) {
+      ::grpc::Service::RequestAsyncBidiStreaming(3, context, stream, new_call_cq, notification_cq, tag);
+    }
+  };
+  typedef WithAsyncMethod_MethodA1<WithAsyncMethod_MethodA2<WithAsyncMethod_MethodA3<WithAsyncMethod_MethodA4<Service > > > > AsyncService;
   template <class BaseClass>
   class WithGenericMethod_MethodA1 : public BaseClass {
    private:
@@ -208,6 +292,40 @@ class ServiceA final {
     }
   };
   template <class BaseClass>
+  class WithGenericMethod_MethodA3 : public BaseClass {
+   private:
+    void BaseClassMustBeDerivedFromService(const Service *service) {}
+   public:
+    WithGenericMethod_MethodA3() {
+      ::grpc::Service::MarkMethodGeneric(2);
+    }
+    ~WithGenericMethod_MethodA3() override {
+      BaseClassMustBeDerivedFromService(this);
+    }
+    // disable synchronous version of this method
+    ::grpc::Status MethodA3(::grpc::ServerContext* context, const ::grpc::testing::Request* request, ::grpc::ServerWriter< ::grpc::testing::Response>* writer) final override {
+      abort();
+      return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
+    }
+  };
+  template <class BaseClass>
+  class WithGenericMethod_MethodA4 : public BaseClass {
+   private:
+    void BaseClassMustBeDerivedFromService(const Service *service) {}
+   public:
+    WithGenericMethod_MethodA4() {
+      ::grpc::Service::MarkMethodGeneric(3);
+    }
+    ~WithGenericMethod_MethodA4() override {
+      BaseClassMustBeDerivedFromService(this);
+    }
+    // disable synchronous version of this method
+    ::grpc::Status MethodA4(::grpc::ServerContext* context, ::grpc::ServerReaderWriter< ::grpc::testing::Response, ::grpc::testing::Request>* stream) final override {
+      abort();
+      return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
+    }
+  };
+  template <class BaseClass>
   class WithStreamedUnaryMethod_MethodA1 : public BaseClass {
    private:
     void BaseClassMustBeDerivedFromService(const Service *service) {}
@@ -228,8 +346,28 @@ class ServiceA final {
     virtual ::grpc::Status StreamedMethodA1(::grpc::ServerContext* context, ::grpc::ServerUnaryStreamer< ::grpc::testing::Request,::grpc::testing::Response>* server_unary_streamer) = 0;
   };
   typedef WithStreamedUnaryMethod_MethodA1<Service > StreamedUnaryService;
-  typedef Service SplitStreamedService;
-  typedef WithStreamedUnaryMethod_MethodA1<Service > StreamedService;
+  template <class BaseClass>
+  class WithSplitStreamingMethod_MethodA3 : public BaseClass {
+   private:
+    void BaseClassMustBeDerivedFromService(const Service *service) {}
+   public:
+    WithSplitStreamingMethod_MethodA3() {
+      ::grpc::Service::MarkMethodStreamed(2,
+        new ::grpc::SplitServerStreamingHandler< ::grpc::testing::Request, ::grpc::testing::Response>(std::bind(&WithSplitStreamingMethod_MethodA3<BaseClass>::StreamedMethodA3, this, std::placeholders::_1, std::placeholders::_2)));
+    }
+    ~WithSplitStreamingMethod_MethodA3() override {
+      BaseClassMustBeDerivedFromService(this);
+    }
+    // disable regular version of this method
+    ::grpc::Status MethodA3(::grpc::ServerContext* context, const ::grpc::testing::Request* request, ::grpc::ServerWriter< ::grpc::testing::Response>* writer) final override {
+      abort();
+      return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
+    }
+    // replace default version of method with split streamed
+    virtual ::grpc::Status StreamedMethodA3(::grpc::ServerContext* context, ::grpc::ServerSplitStreamer< ::grpc::testing::Request,::grpc::testing::Response>* server_split_streamer) = 0;
+  };
+  typedef WithSplitStreamingMethod_MethodA3<Service > SplitStreamedService;
+  typedef WithStreamedUnaryMethod_MethodA1<WithSplitStreamingMethod_MethodA3<Service > > StreamedService;
 };
 
 // ServiceB leading comment 1
diff --git a/test/cpp/codegen/compiler_test_mock_golden b/test/cpp/codegen/compiler_test_mock_golden
new file mode 100644
index 0000000000000000000000000000000000000000..8e4b4d591125289a1f40d9efca66b06bc1ecb453
--- /dev/null
+++ b/test/cpp/codegen/compiler_test_mock_golden
@@ -0,0 +1,34 @@
+// Generated by the gRPC C++ plugin.
+// If you make any local change, they will be lost.
+// source: src/proto/grpc/testing/compiler_test.proto
+
+#include "src/proto/grpc/testing/compiler_test.pb.h"
+#include "src/proto/grpc/testing/compiler_test.grpc.pb.h"
+
+#include <grpc++/impl/codegen/async_stream.h>
+#include <grpc++/impl/codegen/sync_stream.h>
+#include <gmock/gmock.h>
+namespace grpc {
+namespace testing {
+
+class MockServiceAStub : public ServiceA::StubInterface {
+ public:
+  MOCK_METHOD3(MethodA1, ::grpc::Status(::grpc::ClientContext* context, const ::grpc::testing::Request& request, ::grpc::testing::Response* response));
+  MOCK_METHOD3(AsyncMethodA1Raw, ::grpc::ClientAsyncResponseReaderInterface< ::grpc::testing::Response>*(::grpc::ClientContext* context, const ::grpc::testing::Request& request, ::grpc::CompletionQueue* cq));
+  MOCK_METHOD2(MethodA2Raw, ::grpc::ClientWriterInterface< ::grpc::testing::Request>*(::grpc::ClientContext* context, ::grpc::testing::Response* response));
+  MOCK_METHOD4(AsyncMethodA2Raw, ::grpc::ClientAsyncWriterInterface< ::grpc::testing::Request>*(::grpc::ClientContext* context, ::grpc::testing::Response* response, ::grpc::CompletionQueue* cq, void* tag));
+  MOCK_METHOD2(MethodA3Raw, ::grpc::ClientReaderInterface< ::grpc::testing::Response>*(::grpc::ClientContext* context, const ::grpc::testing::Request& request));
+  MOCK_METHOD4(AsyncMethodA3Raw, ::grpc::ClientAsyncReaderInterface< ::grpc::testing::Response>*(::grpc::ClientContext* context, const ::grpc::testing::Request& request, ::grpc::CompletionQueue* cq, void* tag));
+  MOCK_METHOD1(MethodA4Raw, ::grpc::ClientReaderWriterInterface< ::grpc::testing::Request, ::grpc::testing::Response>*(::grpc::ClientContext* context));
+  MOCK_METHOD3(AsyncMethodA4Raw, ::grpc::ClientAsyncReaderWriterInterface<::grpc::testing::Request, ::grpc::testing::Response>*(::grpc::ClientContext* context, ::grpc::CompletionQueue* cq, void* tag));
+};
+
+class MockServiceBStub : public ServiceB::StubInterface {
+ public:
+  MOCK_METHOD3(MethodB1, ::grpc::Status(::grpc::ClientContext* context, const ::grpc::testing::Request& request, ::grpc::testing::Response* response));
+  MOCK_METHOD3(AsyncMethodB1Raw, ::grpc::ClientAsyncResponseReaderInterface< ::grpc::testing::Response>*(::grpc::ClientContext* context, const ::grpc::testing::Request& request, ::grpc::CompletionQueue* cq));
+};
+
+} // namespace grpc
+} // namespace testing
+
diff --git a/test/cpp/codegen/golden_file_test.cc b/test/cpp/codegen/golden_file_test.cc
index 158a4d933c9770d5ee4a18af62edcff1ef3ecacb..7789ac738b931485aa0b071343522320dcb81391 100644
--- a/test/cpp/codegen/golden_file_test.cc
+++ b/test/cpp/codegen/golden_file_test.cc
@@ -37,16 +37,18 @@
 #include <gflags/gflags.h>
 #include <gtest/gtest.h>
 
-DEFINE_string(generated_file_path, "",
-              "path to the generated compiler_test.grpc.pb.h file");
+DEFINE_string(
+    generated_file_path, "",
+    "path to the directory containing generated files compiler_test.grpc.pb.h"
+    "and compiler_test_mock.grpc.pb.h");
 
 const char kGoldenFilePath[] = "test/cpp/codegen/compiler_test_golden";
+const char kMockGoldenFilePath[] = "test/cpp/codegen/compiler_test_mock_golden";
 
-TEST(GoldenFileTest, TestGeneratedFile) {
-  ASSERT_FALSE(FLAGS_generated_file_path.empty());
-
-  std::ifstream generated(FLAGS_generated_file_path);
-  std::ifstream golden(kGoldenFilePath);
+void run_test(std::basic_string<char> generated_file,
+              std::basic_string<char> golden_file) {
+  std::ifstream generated(generated_file);
+  std::ifstream golden(golden_file);
 
   ASSERT_TRUE(generated.good());
   ASSERT_TRUE(golden.good());
@@ -61,8 +63,23 @@ TEST(GoldenFileTest, TestGeneratedFile) {
   golden.close();
 }
 
+TEST(GoldenFileTest, TestGeneratedFile) {
+  run_test(FLAGS_generated_file_path + "compiler_test.grpc.pb.h",
+           kGoldenFilePath);
+}
+
+TEST(GoldenMockFileTest, TestGeneratedMockFile) {
+  run_test(FLAGS_generated_file_path + "compiler_test_mock.grpc.pb.h",
+           kMockGoldenFilePath);
+}
+
 int main(int argc, char **argv) {
   ::testing::InitGoogleTest(&argc, argv);
   ::google::ParseCommandLineFlags(&argc, &argv, true);
+  if (FLAGS_generated_file_path.empty()) {
+    FLAGS_generated_file_path = "gens/src/proto/grpc/testing/";
+  }
+  if (FLAGS_generated_file_path.back() != '/')
+    FLAGS_generated_file_path.append("/");
   return RUN_ALL_TESTS();
 }
diff --git a/test/cpp/end2end/mock_test.cc b/test/cpp/end2end/mock_test.cc
index fdb2732e503d304cbb209905595238bee2fcc8ca..7e330063ed3bec95f7f9ef99e3d5f23fb9e1344f 100644
--- a/test/cpp/end2end/mock_test.cc
+++ b/test/cpp/end2end/mock_test.cc
@@ -34,6 +34,7 @@
 #include <climits>
 #include <thread>
 
+#include <gmock/gmock.h>
 #include <grpc++/channel.h>
 #include <grpc++/client_context.h>
 #include <grpc++/create_channel.h>
@@ -46,120 +47,35 @@
 #include <grpc/support/time.h>
 #include <gtest/gtest.h>
 
+#include <grpc++/test/mock_stream.h>
+
 #include "src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.h"
 #include "src/proto/grpc/testing/echo.grpc.pb.h"
+#include "src/proto/grpc/testing/echo_mock.grpc.pb.h"
 #include "test/core/util/port.h"
 #include "test/core/util/test_config.h"
 
+#include <iostream>
+
+using namespace std;
 using grpc::testing::EchoRequest;
 using grpc::testing::EchoResponse;
 using grpc::testing::EchoTestService;
+using grpc::testing::MockClientReaderWriter;
 using std::chrono::system_clock;
+using ::testing::AtLeast;
+using ::testing::SetArgPointee;
+using ::testing::SaveArg;
+using ::testing::_;
+using ::testing::Return;
+using ::testing::Invoke;
+using ::testing::WithArg;
+using ::testing::DoAll;
 
 namespace grpc {
 namespace testing {
 
 namespace {
-template <class W, class R>
-class MockClientReaderWriter final : public ClientReaderWriterInterface<W, R> {
- public:
-  void WaitForInitialMetadata() override {}
-  bool NextMessageSize(uint32_t* sz) override {
-    *sz = UINT_MAX;
-    return true;
-  }
-  bool Read(R* msg) override { return true; }
-  bool Write(const W& msg) override { return true; }
-  bool WritesDone() override { return true; }
-  Status Finish() override { return Status::OK; }
-};
-template <>
-class MockClientReaderWriter<EchoRequest, EchoResponse> final
-    : public ClientReaderWriterInterface<EchoRequest, EchoResponse> {
- public:
-  MockClientReaderWriter() : writes_done_(false) {}
-  void WaitForInitialMetadata() override {}
-  bool NextMessageSize(uint32_t* sz) override {
-    *sz = UINT_MAX;
-    return true;
-  }
-  bool Read(EchoResponse* msg) override {
-    if (writes_done_) return false;
-    msg->set_message(last_message_);
-    return true;
-  }
-
-  bool Write(const EchoRequest& msg, WriteOptions options) override {
-    gpr_log(GPR_INFO, "mock recv msg %s", msg.message().c_str());
-    last_message_ = msg.message();
-    return true;
-  }
-  bool WritesDone() override {
-    writes_done_ = true;
-    return true;
-  }
-  Status Finish() override { return Status::OK; }
-
- private:
-  bool writes_done_;
-  grpc::string last_message_;
-};
-
-// Mocked stub.
-class MockStub : public EchoTestService::StubInterface {
- public:
-  MockStub() {}
-  ~MockStub() {}
-  Status Echo(ClientContext* context, const EchoRequest& request,
-              EchoResponse* response) override {
-    response->set_message(request.message());
-    return Status::OK;
-  }
-  Status Unimplemented(ClientContext* context, const EchoRequest& request,
-                       EchoResponse* response) override {
-    return Status::OK;
-  }
-
- private:
-  ClientAsyncResponseReaderInterface<EchoResponse>* AsyncEchoRaw(
-      ClientContext* context, const EchoRequest& request,
-      CompletionQueue* cq) override {
-    return nullptr;
-  }
-  ClientWriterInterface<EchoRequest>* RequestStreamRaw(
-      ClientContext* context, EchoResponse* response) override {
-    return nullptr;
-  }
-  ClientAsyncWriterInterface<EchoRequest>* AsyncRequestStreamRaw(
-      ClientContext* context, EchoResponse* response, CompletionQueue* cq,
-      void* tag) override {
-    return nullptr;
-  }
-  ClientReaderInterface<EchoResponse>* ResponseStreamRaw(
-      ClientContext* context, const EchoRequest& request) override {
-    return nullptr;
-  }
-  ClientAsyncReaderInterface<EchoResponse>* AsyncResponseStreamRaw(
-      ClientContext* context, const EchoRequest& request, CompletionQueue* cq,
-      void* tag) override {
-    return nullptr;
-  }
-  ClientReaderWriterInterface<EchoRequest, EchoResponse>* BidiStreamRaw(
-      ClientContext* context) override {
-    return new MockClientReaderWriter<EchoRequest, EchoResponse>();
-  }
-  ClientAsyncReaderWriterInterface<EchoRequest, EchoResponse>*
-  AsyncBidiStreamRaw(ClientContext* context, CompletionQueue* cq,
-                     void* tag) override {
-    return nullptr;
-  }
-  ClientAsyncResponseReaderInterface<EchoResponse>* AsyncUnimplementedRaw(
-      ClientContext* context, const EchoRequest& request,
-      CompletionQueue* cq) override {
-    return nullptr;
-  }
-};
-
 class FakeClient {
  public:
   explicit FakeClient(EchoTestService::StubInterface* stub) : stub_(stub) {}
@@ -174,6 +90,55 @@ class FakeClient {
     EXPECT_TRUE(s.ok());
   }
 
+  void DoRequestStream() {
+    EchoRequest request;
+    EchoResponse response;
+
+    ClientContext context;
+    grpc::string msg("hello");
+    grpc::string exp(msg);
+
+    std::unique_ptr<ClientWriterInterface<EchoRequest>> cstream =
+        stub_->RequestStream(&context, &response);
+
+    request.set_message(msg);
+    EXPECT_TRUE(cstream->Write(request));
+
+    msg = ", world";
+    request.set_message(msg);
+    exp.append(msg);
+    EXPECT_TRUE(cstream->Write(request));
+
+    cstream->WritesDone();
+    Status s = cstream->Finish();
+
+    EXPECT_EQ(exp, response.message());
+    EXPECT_TRUE(s.ok());
+  }
+
+  void DoResponseStream() {
+    EchoRequest request;
+    EchoResponse response;
+    request.set_message("hello world");
+
+    ClientContext context;
+    std::unique_ptr<ClientReaderInterface<EchoResponse>> cstream =
+        stub_->ResponseStream(&context, request);
+
+    grpc::string exp = "";
+    EXPECT_TRUE(cstream->Read(&response));
+    exp.append(response.message() + " ");
+
+    EXPECT_TRUE(cstream->Read(&response));
+    exp.append(response.message());
+
+    EXPECT_FALSE(cstream->Read(&response));
+    EXPECT_EQ(request.message(), exp);
+
+    Status s = cstream->Finish();
+    EXPECT_TRUE(s.ok());
+  }
+
   void DoBidiStream() {
     EchoRequest request;
     EchoResponse response;
@@ -219,6 +184,30 @@ class TestServiceImpl : public EchoTestService::Service {
     return Status::OK;
   }
 
+  Status RequestStream(ServerContext* context,
+                       ServerReader<EchoRequest>* reader,
+                       EchoResponse* response) override {
+    EchoRequest request;
+    grpc::string resp("");
+    while (reader->Read(&request)) {
+      gpr_log(GPR_INFO, "recv msg %s", request.message().c_str());
+      resp.append(request.message());
+    }
+    response->set_message(resp);
+    return Status::OK;
+  }
+
+  Status ResponseStream(ServerContext* context, const EchoRequest* request,
+                        ServerWriter<EchoResponse>* writer) override {
+    EchoResponse response;
+    vector<grpc::string> tokens = split(request->message());
+    for (grpc::string token : tokens) {
+      response.set_message(token);
+      writer->Write(response);
+    }
+    return Status::OK;
+  }
+
   Status BidiStream(
       ServerContext* context,
       ServerReaderWriter<EchoResponse, EchoRequest>* stream) override {
@@ -231,6 +220,25 @@ class TestServiceImpl : public EchoTestService::Service {
     }
     return Status::OK;
   }
+
+ private:
+  const vector<grpc::string> split(const grpc::string& input) {
+    grpc::string buff("");
+    vector<grpc::string> result;
+
+    for (auto n : input) {
+      if (n != ' ') {
+        buff += n;
+        continue;
+      }
+      if (buff == "") continue;
+      result.push_back(buff);
+      buff = "";
+    }
+    if (buff != "") result.push_back(buff);
+
+    return result;
+  }
 };
 
 class MockTest : public ::testing::Test {
@@ -267,16 +275,82 @@ TEST_F(MockTest, SimpleRpc) {
   ResetStub();
   FakeClient client(stub_.get());
   client.DoEcho();
-  MockStub stub;
+  MockEchoTestServiceStub stub;
+  EchoResponse resp;
+  resp.set_message("hello world");
+  EXPECT_CALL(stub, Echo(_, _, _))
+      .Times(AtLeast(1))
+      .WillOnce(DoAll(SetArgPointee<2>(resp), Return(Status::OK)));
   client.ResetStub(&stub);
   client.DoEcho();
 }
 
+TEST_F(MockTest, ClientStream) {
+  ResetStub();
+  FakeClient client(stub_.get());
+  client.DoRequestStream();
+
+  MockEchoTestServiceStub stub;
+  auto w = new MockClientWriter<EchoRequest>();
+  EchoResponse resp;
+  resp.set_message("hello, world");
+
+  EXPECT_CALL(*w, Write(_, _)).Times(2).WillRepeatedly(Return(true));
+  EXPECT_CALL(*w, WritesDone());
+  EXPECT_CALL(*w, Finish()).WillOnce(Return(Status::OK));
+
+  EXPECT_CALL(stub, RequestStreamRaw(_, _))
+      .WillOnce(DoAll(SetArgPointee<1>(resp), Return(w)));
+  client.ResetStub(&stub);
+  client.DoRequestStream();
+}
+
+TEST_F(MockTest, ServerStream) {
+  ResetStub();
+  FakeClient client(stub_.get());
+  client.DoResponseStream();
+
+  MockEchoTestServiceStub stub;
+  auto r = new MockClientReader<EchoResponse>();
+  EchoResponse resp1;
+  resp1.set_message("hello");
+  EchoResponse resp2;
+  resp2.set_message("world");
+
+  EXPECT_CALL(*r, Read(_))
+      .WillOnce(DoAll(SetArgPointee<0>(resp1), Return(true)))
+      .WillOnce(DoAll(SetArgPointee<0>(resp2), Return(true)))
+      .WillOnce(Return(false));
+  EXPECT_CALL(*r, Finish()).WillOnce(Return(Status::OK));
+
+  EXPECT_CALL(stub, ResponseStreamRaw(_, _)).WillOnce(Return(r));
+
+  client.ResetStub(&stub);
+  client.DoResponseStream();
+}
+
+ACTION_P(copy, msg) { arg0->set_message(msg->message()); }
+
 TEST_F(MockTest, BidiStream) {
   ResetStub();
   FakeClient client(stub_.get());
   client.DoBidiStream();
-  MockStub stub;
+  MockEchoTestServiceStub stub;
+  auto rw = new MockClientReaderWriter<EchoRequest, EchoResponse>();
+  EchoRequest msg;
+
+  EXPECT_CALL(*rw, Write(_, _))
+      .Times(3)
+      .WillRepeatedly(DoAll(SaveArg<0>(&msg), Return(true)));
+  EXPECT_CALL(*rw, Read(_))
+      .WillOnce(DoAll(WithArg<0>(copy(&msg)), Return(true)))
+      .WillOnce(DoAll(WithArg<0>(copy(&msg)), Return(true)))
+      .WillOnce(DoAll(WithArg<0>(copy(&msg)), Return(true)))
+      .WillOnce(Return(false));
+  EXPECT_CALL(*rw, WritesDone());
+  EXPECT_CALL(*rw, Finish()).WillOnce(Return(Status::OK));
+
+  EXPECT_CALL(stub, BidiStreamRaw(_)).WillOnce(Return(rw));
   client.ResetStub(&stub);
   client.DoBidiStream();
 }
diff --git a/third_party/gtest.BUILD b/third_party/gtest.BUILD
index 52c9ca2ba7c2537b204929b6d8fe3d7294e1af17..b70f2c51bcf3c1c7b7f943a1eee406c208f5400c 100644
--- a/third_party/gtest.BUILD
+++ b/third_party/gtest.BUILD
@@ -2,11 +2,14 @@ cc_library(
     name = "gtest",
     srcs = [
         "googletest/src/gtest-all.cc",
+	"googlemock/src/gmock-all.cc"
     ],
-    hdrs = glob(["googletest/include/**/*.h", "googletest/src/*.cc", "googletest/src/*.h"]),
+    hdrs = glob(["googletest/include/**/*.h", "googletest/src/*.cc", "googletest/src/*.h", "googlemock/include/**/*.h", "googlemock/src/*.cc", "googlemock/src/*.h"]),
     includes = [
         "googletest",
         "googletest/include",
+	"googlemock",
+	"googlemock/include",
     ],
     linkstatic = 1,
     visibility = [
diff --git a/tools/run_tests/generated/sources_and_headers.json b/tools/run_tests/generated/sources_and_headers.json
index d053fff364a61dc3bfa5d6b1af308157ebcf09dc..6ef1c13b102eedb4391fed26b8053375b2d434c7 100644
--- a/tools/run_tests/generated/sources_and_headers.json
+++ b/tools/run_tests/generated/sources_and_headers.json
@@ -2871,14 +2871,19 @@
     "headers": [
       "src/proto/grpc/testing/control.grpc.pb.h", 
       "src/proto/grpc/testing/control.pb.h", 
+      "src/proto/grpc/testing/control_mock.grpc.pb.h", 
       "src/proto/grpc/testing/messages.grpc.pb.h", 
       "src/proto/grpc/testing/messages.pb.h", 
+      "src/proto/grpc/testing/messages_mock.grpc.pb.h", 
       "src/proto/grpc/testing/payloads.grpc.pb.h", 
       "src/proto/grpc/testing/payloads.pb.h", 
+      "src/proto/grpc/testing/payloads_mock.grpc.pb.h", 
       "src/proto/grpc/testing/services.grpc.pb.h", 
       "src/proto/grpc/testing/services.pb.h", 
+      "src/proto/grpc/testing/services_mock.grpc.pb.h", 
       "src/proto/grpc/testing/stats.grpc.pb.h", 
-      "src/proto/grpc/testing/stats.pb.h"
+      "src/proto/grpc/testing/stats.pb.h", 
+      "src/proto/grpc/testing/stats_mock.grpc.pb.h"
     ], 
     "is_filegroup": false, 
     "language": "c++", 
@@ -2899,14 +2904,19 @@
     "headers": [
       "src/proto/grpc/testing/control.grpc.pb.h", 
       "src/proto/grpc/testing/control.pb.h", 
+      "src/proto/grpc/testing/control_mock.grpc.pb.h", 
       "src/proto/grpc/testing/messages.grpc.pb.h", 
       "src/proto/grpc/testing/messages.pb.h", 
+      "src/proto/grpc/testing/messages_mock.grpc.pb.h", 
       "src/proto/grpc/testing/payloads.grpc.pb.h", 
       "src/proto/grpc/testing/payloads.pb.h", 
+      "src/proto/grpc/testing/payloads_mock.grpc.pb.h", 
       "src/proto/grpc/testing/services.grpc.pb.h", 
       "src/proto/grpc/testing/services.pb.h", 
+      "src/proto/grpc/testing/services_mock.grpc.pb.h", 
       "src/proto/grpc/testing/stats.grpc.pb.h", 
-      "src/proto/grpc/testing/stats.pb.h"
+      "src/proto/grpc/testing/stats.pb.h", 
+      "src/proto/grpc/testing/stats_mock.grpc.pb.h"
     ], 
     "is_filegroup": false, 
     "language": "c++", 
@@ -3027,7 +3037,8 @@
     ], 
     "headers": [
       "src/proto/grpc/testing/echo_messages.grpc.pb.h", 
-      "src/proto/grpc/testing/echo_messages.pb.h"
+      "src/proto/grpc/testing/echo_messages.pb.h", 
+      "src/proto/grpc/testing/echo_messages_mock.grpc.pb.h"
     ], 
     "is_filegroup": false, 
     "language": "c++", 
@@ -3084,7 +3095,8 @@
     ], 
     "headers": [
       "src/proto/grpc/testing/compiler_test.grpc.pb.h", 
-      "src/proto/grpc/testing/compiler_test.pb.h"
+      "src/proto/grpc/testing/compiler_test.pb.h", 
+      "src/proto/grpc/testing/compiler_test_mock.grpc.pb.h"
     ], 
     "is_filegroup": false, 
     "language": "c++", 
@@ -3229,7 +3241,9 @@
       "src/proto/grpc/testing/echo.grpc.pb.h", 
       "src/proto/grpc/testing/echo.pb.h", 
       "src/proto/grpc/testing/echo_messages.grpc.pb.h", 
-      "src/proto/grpc/testing/echo_messages.pb.h"
+      "src/proto/grpc/testing/echo_messages.pb.h", 
+      "src/proto/grpc/testing/echo_messages_mock.grpc.pb.h", 
+      "src/proto/grpc/testing/echo_mock.grpc.pb.h"
     ], 
     "is_filegroup": false, 
     "language": "c++", 
@@ -3249,7 +3263,8 @@
     ], 
     "headers": [
       "src/proto/grpc/lb/v1/load_balancer.grpc.pb.h", 
-      "src/proto/grpc/lb/v1/load_balancer.pb.h"
+      "src/proto/grpc/lb/v1/load_balancer.pb.h", 
+      "src/proto/grpc/lb/v1/load_balancer_mock.grpc.pb.h"
     ], 
     "is_filegroup": false, 
     "language": "c++", 
@@ -3271,7 +3286,8 @@
     ], 
     "headers": [
       "src/proto/grpc/lb/v1/load_balancer.grpc.pb.h", 
-      "src/proto/grpc/lb/v1/load_balancer.pb.h"
+      "src/proto/grpc/lb/v1/load_balancer.pb.h", 
+      "src/proto/grpc/lb/v1/load_balancer_mock.grpc.pb.h"
     ], 
     "is_filegroup": false, 
     "language": "c++", 
@@ -3426,6 +3442,7 @@
     "headers": [
       "src/proto/grpc/testing/metrics.grpc.pb.h", 
       "src/proto/grpc/testing/metrics.pb.h", 
+      "src/proto/grpc/testing/metrics_mock.grpc.pb.h", 
       "test/cpp/util/metrics_server.h"
     ], 
     "is_filegroup": false, 
@@ -3447,11 +3464,14 @@
       "grpc++_test_util", 
       "grpc_test_util"
     ], 
-    "headers": [], 
+    "headers": [
+      "include/grpc++/test/mock_stream.h"
+    ], 
     "is_filegroup": false, 
     "language": "c++", 
     "name": "mock_test", 
     "src": [
+      "include/grpc++/test/mock_stream.h", 
       "test/cpp/end2end/mock_test.cc"
     ], 
     "third_party": false, 
@@ -3610,10 +3630,13 @@
     "headers": [
       "src/proto/grpc/testing/empty.grpc.pb.h", 
       "src/proto/grpc/testing/empty.pb.h", 
+      "src/proto/grpc/testing/empty_mock.grpc.pb.h", 
       "src/proto/grpc/testing/messages.grpc.pb.h", 
       "src/proto/grpc/testing/messages.pb.h", 
+      "src/proto/grpc/testing/messages_mock.grpc.pb.h", 
       "src/proto/grpc/testing/test.grpc.pb.h", 
-      "src/proto/grpc/testing/test.pb.h"
+      "src/proto/grpc/testing/test.pb.h", 
+      "src/proto/grpc/testing/test_mock.grpc.pb.h"
     ], 
     "is_filegroup": false, 
     "language": "c++", 
@@ -3639,10 +3662,13 @@
     "headers": [
       "src/proto/grpc/testing/empty.grpc.pb.h", 
       "src/proto/grpc/testing/empty.pb.h", 
+      "src/proto/grpc/testing/empty_mock.grpc.pb.h", 
       "src/proto/grpc/testing/messages.grpc.pb.h", 
       "src/proto/grpc/testing/messages.pb.h", 
+      "src/proto/grpc/testing/messages_mock.grpc.pb.h", 
       "src/proto/grpc/testing/test.grpc.pb.h", 
-      "src/proto/grpc/testing/test.pb.h"
+      "src/proto/grpc/testing/test.pb.h", 
+      "src/proto/grpc/testing/test_mock.grpc.pb.h"
     ], 
     "is_filegroup": false, 
     "language": "c++", 
@@ -3743,7 +3769,9 @@
       "src/proto/grpc/testing/echo.grpc.pb.h", 
       "src/proto/grpc/testing/echo.pb.h", 
       "src/proto/grpc/testing/echo_messages.grpc.pb.h", 
-      "src/proto/grpc/testing/echo_messages.pb.h"
+      "src/proto/grpc/testing/echo_messages.pb.h", 
+      "src/proto/grpc/testing/echo_messages_mock.grpc.pb.h", 
+      "src/proto/grpc/testing/echo_mock.grpc.pb.h"
     ], 
     "is_filegroup": false, 
     "language": "c++", 
@@ -3880,12 +3908,16 @@
     "headers": [
       "src/proto/grpc/testing/empty.grpc.pb.h", 
       "src/proto/grpc/testing/empty.pb.h", 
+      "src/proto/grpc/testing/empty_mock.grpc.pb.h", 
       "src/proto/grpc/testing/messages.grpc.pb.h", 
       "src/proto/grpc/testing/messages.pb.h", 
+      "src/proto/grpc/testing/messages_mock.grpc.pb.h", 
       "src/proto/grpc/testing/metrics.grpc.pb.h", 
       "src/proto/grpc/testing/metrics.pb.h", 
+      "src/proto/grpc/testing/metrics_mock.grpc.pb.h", 
       "src/proto/grpc/testing/test.grpc.pb.h", 
       "src/proto/grpc/testing/test.pb.h", 
+      "src/proto/grpc/testing/test_mock.grpc.pb.h", 
       "test/cpp/interop/client_helper.h", 
       "test/cpp/interop/interop_client.h", 
       "test/cpp/interop/stress_interop_client.h", 
@@ -5900,7 +5932,8 @@
     "headers": [
       "include/grpc++/support/error_details.h", 
       "src/proto/grpc/status/status.grpc.pb.h", 
-      "src/proto/grpc/status/status.pb.h"
+      "src/proto/grpc/status/status.pb.h", 
+      "src/proto/grpc/status/status_mock.grpc.pb.h"
     ], 
     "is_filegroup": false, 
     "language": "c++", 
@@ -5980,12 +6013,16 @@
     "headers": [
       "src/proto/grpc/health/v1/health.grpc.pb.h", 
       "src/proto/grpc/health/v1/health.pb.h", 
+      "src/proto/grpc/health/v1/health_mock.grpc.pb.h", 
       "src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.h", 
       "src/proto/grpc/testing/duplicate/echo_duplicate.pb.h", 
+      "src/proto/grpc/testing/duplicate/echo_duplicate_mock.grpc.pb.h", 
       "src/proto/grpc/testing/echo.grpc.pb.h", 
       "src/proto/grpc/testing/echo.pb.h", 
       "src/proto/grpc/testing/echo_messages.grpc.pb.h", 
       "src/proto/grpc/testing/echo_messages.pb.h", 
+      "src/proto/grpc/testing/echo_messages_mock.grpc.pb.h", 
+      "src/proto/grpc/testing/echo_mock.grpc.pb.h", 
       "test/cpp/end2end/test_service_impl.h", 
       "test/cpp/util/byte_buffer_proto_helper.h", 
       "test/cpp/util/create_test_channel.h", 
@@ -6165,10 +6202,13 @@
     "headers": [
       "src/proto/grpc/testing/empty.grpc.pb.h", 
       "src/proto/grpc/testing/empty.pb.h", 
+      "src/proto/grpc/testing/empty_mock.grpc.pb.h", 
       "src/proto/grpc/testing/messages.grpc.pb.h", 
       "src/proto/grpc/testing/messages.pb.h", 
+      "src/proto/grpc/testing/messages_mock.grpc.pb.h", 
       "src/proto/grpc/testing/test.grpc.pb.h", 
       "src/proto/grpc/testing/test.pb.h", 
+      "src/proto/grpc/testing/test_mock.grpc.pb.h", 
       "test/cpp/interop/http2_client.h"
     ], 
     "is_filegroup": false, 
@@ -6192,6 +6232,7 @@
     "headers": [
       "src/proto/grpc/testing/messages.grpc.pb.h", 
       "src/proto/grpc/testing/messages.pb.h", 
+      "src/proto/grpc/testing/messages_mock.grpc.pb.h", 
       "test/cpp/interop/client_helper.h"
     ], 
     "is_filegroup": false, 
@@ -6218,10 +6259,13 @@
     "headers": [
       "src/proto/grpc/testing/empty.grpc.pb.h", 
       "src/proto/grpc/testing/empty.pb.h", 
+      "src/proto/grpc/testing/empty_mock.grpc.pb.h", 
       "src/proto/grpc/testing/messages.grpc.pb.h", 
       "src/proto/grpc/testing/messages.pb.h", 
+      "src/proto/grpc/testing/messages_mock.grpc.pb.h", 
       "src/proto/grpc/testing/test.grpc.pb.h", 
       "src/proto/grpc/testing/test.pb.h", 
+      "src/proto/grpc/testing/test_mock.grpc.pb.h", 
       "test/cpp/interop/interop_client.h"
     ], 
     "is_filegroup": false, 
@@ -6270,10 +6314,13 @@
     "headers": [
       "src/proto/grpc/testing/empty.grpc.pb.h", 
       "src/proto/grpc/testing/empty.pb.h", 
+      "src/proto/grpc/testing/empty_mock.grpc.pb.h", 
       "src/proto/grpc/testing/messages.grpc.pb.h", 
       "src/proto/grpc/testing/messages.pb.h", 
+      "src/proto/grpc/testing/messages_mock.grpc.pb.h", 
       "src/proto/grpc/testing/test.grpc.pb.h", 
-      "src/proto/grpc/testing/test.pb.h"
+      "src/proto/grpc/testing/test.pb.h", 
+      "src/proto/grpc/testing/test_mock.grpc.pb.h"
     ], 
     "is_filegroup": false, 
     "language": "c++", 
@@ -6307,14 +6354,19 @@
     "headers": [
       "src/proto/grpc/testing/control.grpc.pb.h", 
       "src/proto/grpc/testing/control.pb.h", 
+      "src/proto/grpc/testing/control_mock.grpc.pb.h", 
       "src/proto/grpc/testing/messages.grpc.pb.h", 
       "src/proto/grpc/testing/messages.pb.h", 
+      "src/proto/grpc/testing/messages_mock.grpc.pb.h", 
       "src/proto/grpc/testing/payloads.grpc.pb.h", 
       "src/proto/grpc/testing/payloads.pb.h", 
+      "src/proto/grpc/testing/payloads_mock.grpc.pb.h", 
       "src/proto/grpc/testing/services.grpc.pb.h", 
       "src/proto/grpc/testing/services.pb.h", 
+      "src/proto/grpc/testing/services_mock.grpc.pb.h", 
       "src/proto/grpc/testing/stats.grpc.pb.h", 
       "src/proto/grpc/testing/stats.pb.h", 
+      "src/proto/grpc/testing/stats_mock.grpc.pb.h", 
       "test/cpp/qps/benchmark_config.h", 
       "test/cpp/qps/client.h", 
       "test/cpp/qps/driver.h", 
@@ -9023,7 +9075,8 @@
     "deps": [], 
     "headers": [
       "src/proto/grpc/reflection/v1alpha/reflection.grpc.pb.h", 
-      "src/proto/grpc/reflection/v1alpha/reflection.pb.h"
+      "src/proto/grpc/reflection/v1alpha/reflection.pb.h", 
+      "src/proto/grpc/reflection/v1alpha/reflection_mock.grpc.pb.h"
     ], 
     "is_filegroup": true, 
     "language": "c++", 
@@ -9037,12 +9090,14 @@
       "grpc++"
     ], 
     "headers": [
+      "include/grpc++/test/mock_stream.h", 
       "include/grpc++/test/server_context_test_spouse.h"
     ], 
     "is_filegroup": true, 
     "language": "c++", 
     "name": "grpc++_test", 
     "src": [
+      "include/grpc++/test/mock_stream.h", 
       "include/grpc++/test/server_context_test_spouse.h"
     ], 
     "third_party": false, 
diff --git a/tools/run_tests/generated/tests.json b/tools/run_tests/generated/tests.json
index 120a84e8a4bb91e27734a1823ae0ed86e4c3ae90..058127862ea9eb3b150fb0a9acc899897c5ccb78 100644
--- a/tools/run_tests/generated/tests.json
+++ b/tools/run_tests/generated/tests.json
@@ -3329,7 +3329,7 @@
   }, 
   {
     "args": [
-      "--generated_file_path=gens/src/proto/grpc/testing/compiler_test.grpc.pb.h"
+      "--generated_file_path=gens/src/proto/grpc/testing/"
     ], 
     "ci_platforms": [
       "linux", 
diff --git a/tools/run_tests/python_utils/port_server.py b/tools/run_tests/python_utils/port_server.py
index dbd32efc0e8eab22abb94cb667177195f20e6c45..522cbed9e1c56f50d9a186547ffb20a31b5e8860 100755
--- a/tools/run_tests/python_utils/port_server.py
+++ b/tools/run_tests/python_utils/port_server.py
@@ -33,18 +33,20 @@
 from __future__ import print_function
 
 import argparse
-from six.moves import BaseHTTPServer
+from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler
 import hashlib
 import os
 import socket
 import sys
 import time
+from SocketServer import ThreadingMixIn
+import threading
 
 
 # increment this number whenever making a change to ensure that
 # the changes are picked up by running CI servers
 # note that all changes must be backwards compatible
-_MY_VERSION = 9
+_MY_VERSION = 11
 
 
 if len(sys.argv) == 2 and sys.argv[1] == 'dump_version':
@@ -68,6 +70,7 @@ print('port server running on port %d' % args.port)
 
 pool = []
 in_use = {}
+mu = threading.Lock()
 
 
 def refill_pool(max_timeout, req):
@@ -95,28 +98,33 @@ def refill_pool(max_timeout, req):
 def allocate_port(req):
   global pool
   global in_use
+  global mu
+  mu.acquire()
   max_timeout = 600
   while not pool:
     refill_pool(max_timeout, req)
     if not pool:
       req.log_message("failed to find ports: retrying soon")
+      mu.release()
       time.sleep(1)
+      mu.acquire()
       max_timeout /= 2
   port = pool[0]
   pool = pool[1:]
   in_use[port] = time.time()
+  mu.release()
   return port
 
 
 keep_running = True
 
 
-class Handler(BaseHTTPServer.BaseHTTPRequestHandler):
+class Handler(BaseHTTPRequestHandler):
   
   def setup(self):
     # If the client is unreachable for 5 seconds, close the connection
     self.timeout = 5
-    BaseHTTPServer.BaseHTTPRequestHandler.setup(self)
+    BaseHTTPRequestHandler.setup(self)
 
   def do_GET(self):
     global keep_running
@@ -158,12 +166,12 @@ class Handler(BaseHTTPServer.BaseHTTPRequestHandler):
     elif self.path == '/quitquitquit':
       self.send_response(200)
       self.end_headers()
-      keep_running = False
+      sys.exit(0)
 
+class ThreadedHTTPServer(ThreadingMixIn, HTTPServer):
+  """Handle requests in a separate thread"""
 
-httpd = BaseHTTPServer.HTTPServer(('', args.port), Handler)
-while keep_running:
-  httpd.handle_request()
-  sys.stderr.flush()
 
-print('done')
+httpd = ThreadedHTTPServer(('', args.port), Handler)
+httpd.serve_forever()
+
diff --git a/vsprojects/vcxproj/test/mock_test/mock_test.vcxproj b/vsprojects/vcxproj/test/mock_test/mock_test.vcxproj
index 8c840fd5be902b345e94febc95a0db1a4dd2958e..bc1cae591172401fa349dd588892a3ee4d7482e8 100644
--- a/vsprojects/vcxproj/test/mock_test/mock_test.vcxproj
+++ b/vsprojects/vcxproj/test/mock_test/mock_test.vcxproj
@@ -159,6 +159,9 @@
     </Link>
   </ItemDefinitionGroup>
 
+  <ItemGroup>
+    <ClInclude Include="$(SolutionDir)\..\include\grpc++\test\mock_stream.h" />
+  </ItemGroup>
   <ItemGroup>
     <ClCompile Include="$(SolutionDir)\..\test\cpp\end2end\mock_test.cc">
     </ClCompile>
diff --git a/vsprojects/vcxproj/test/mock_test/mock_test.vcxproj.filters b/vsprojects/vcxproj/test/mock_test/mock_test.vcxproj.filters
index 1b3b773b08fc1227c64bc47056306a4190e39902..6db61c9037b783eea98eaa24d63d411735033a57 100644
--- a/vsprojects/vcxproj/test/mock_test/mock_test.vcxproj.filters
+++ b/vsprojects/vcxproj/test/mock_test/mock_test.vcxproj.filters
@@ -5,8 +5,22 @@
       <Filter>test\cpp\end2end</Filter>
     </ClCompile>
   </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="$(SolutionDir)\..\include\grpc++\test\mock_stream.h">
+      <Filter>include\grpc++\test</Filter>
+    </ClInclude>
+  </ItemGroup>
 
   <ItemGroup>
+    <Filter Include="include">
+      <UniqueIdentifier>{b827d6d2-cfa5-2dd4-6ebc-afcccd5e8e0c}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="include\grpc++">
+      <UniqueIdentifier>{28289e8f-b68e-b9f5-7680-c15d77b574a5}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="include\grpc++\test">
+      <UniqueIdentifier>{4a7b43be-c730-6221-d190-e394521f9ae7}</UniqueIdentifier>
+    </Filter>
     <Filter Include="test">
       <UniqueIdentifier>{69c257a2-3e4c-a86e-ce0d-1a97b237d294}</UniqueIdentifier>
     </Filter>