Matches the SetDefaultEventEngineFactory definition to its declaration (#28707)

* Matches the SetDefaultEventEngineFactory definition to its declaration

+`const`

* Add smoke test for SetDefaultEventEngineFactory

* Automated change: Fix sanity tests

* anonymous namespace

Co-authored-by: drfloob <drfloob@users.noreply.github.com>

CMakeLists.txt

@@ -979,6 +979,7 @@ if(gRPC_BUILD_TESTS)
   add_dependencies(buildtests_cxx settings_timeout_test)
   add_dependencies(buildtests_cxx shutdown_test)
   add_dependencies(buildtests_cxx simple_request_bad_client_test)
+  add_dependencies(buildtests_cxx smoke_test)
   add_dependencies(buildtests_cxx sockaddr_utils_test)
   if(_gRPC_PLATFORM_LINUX OR _gRPC_PLATFORM_MAC OR _gRPC_PLATFORM_POSIX)
     add_dependencies(buildtests_cxx stack_tracer_test)
@@ -15173,6 +15174,41 @@ target_link_libraries(simple_request_bad_client_test
 )
 
 
+endif()
+if(gRPC_BUILD_TESTS)
+
+add_executable(smoke_test
+  test/core/event_engine/smoke_test.cc
+  third_party/googletest/googletest/src/gtest-all.cc
+  third_party/googletest/googlemock/src/gmock-all.cc
+)
+
+target_include_directories(smoke_test
+  PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}
+    ${CMAKE_CURRENT_SOURCE_DIR}/include
+    ${_gRPC_ADDRESS_SORTING_INCLUDE_DIR}
+    ${_gRPC_RE2_INCLUDE_DIR}
+    ${_gRPC_SSL_INCLUDE_DIR}
+    ${_gRPC_UPB_GENERATED_DIR}
+    ${_gRPC_UPB_GRPC_GENERATED_DIR}
+    ${_gRPC_UPB_INCLUDE_DIR}
+    ${_gRPC_XXHASH_INCLUDE_DIR}
+    ${_gRPC_ZLIB_INCLUDE_DIR}
+    third_party/googletest/googletest/include
+    third_party/googletest/googletest
+    third_party/googletest/googlemock/include
+    third_party/googletest/googlemock
+    ${_gRPC_PROTO_GENS_DIR}
+)
+
+target_link_libraries(smoke_test
+  ${_gRPC_PROTOBUF_LIBRARIES}
+  ${_gRPC_ALLTARGETS_LIBRARIES}
+  grpc_test_util
+)
+
+
 endif()
 if(gRPC_BUILD_TESTS)
 

build_autogenerated.yaml

@@ -7750,6 +7750,15 @@ targets:
   - test/core/end2end/cq_verifier.cc
   deps:
   - grpc_test_util
+- name: smoke_test
+  gtest: true
+  build: test
+  language: c++
+  headers: []
+  src:
+  - test/core/event_engine/smoke_test.cc
+  deps:
+  - grpc_test_util
 - name: sockaddr_utils_test
   gtest: true
   build: test

src/core/lib/event_engine/event_engine_factory.cc

@@ -21,7 +21,8 @@ namespace grpc_event_engine {
 namespace experimental {
 
 namespace {
-std::function<std::unique_ptr<EventEngine>()>* g_event_engine_factory = nullptr;
+const std::function<std::unique_ptr<EventEngine>()>* g_event_engine_factory =
+    nullptr;
 grpc_core::Mutex* g_mu = new grpc_core::Mutex();
 }  // namespace
 
@@ -31,7 +32,7 @@ EventEngine* GetDefaultEventEngine() {
 }
 
 void SetDefaultEventEngineFactory(
-    std::function<std::unique_ptr<EventEngine>()>* factory) {
+    const std::function<std::unique_ptr<EventEngine>()>* factory) {
   grpc_core::MutexLock lock(g_mu);
   g_event_engine_factory = factory;
 }

test/core/event_engine/BUILD

@@ -49,3 +49,13 @@ grpc_cc_library(
     # Ensure the linker doesn't throw away test cases.
     alwayslink = 1,
 )
+
+grpc_cc_test(
+    name = "smoke_test",
+    srcs = ["smoke_test.cc"],
+    external_deps = ["gtest"],
+    deps = [
+        "//:grpc",
+        "//test/core/util:grpc_test_util",
+    ],
+)

test/core/event_engine/smoke_test.cc

@@ -0,0 +1,50 @@
+// Copyright 2022 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#include <grpc/support/port_platform.h>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <grpc/event_engine/event_engine.h>
+#include <grpc/grpc.h>
+
+#include "test/core/util/test_config.h"
+
+namespace {
+
+using ::testing::MockFunction;
+
+class EventEngineSmokeTest : public testing::Test {};
+
+TEST_F(EventEngineSmokeTest, SetDefaultEventEngineFactoryLinks) {
+  // See https://github.com/grpc/grpc/pull/28707
+  testing::MockFunction<
+      std::unique_ptr<grpc_event_engine::experimental::EventEngine>()>
+      factory;
+  EXPECT_CALL(factory, Call()).Times(1);
+  auto stdfn_fact = factory.AsStdFunction();
+  grpc_event_engine::experimental::SetDefaultEventEngineFactory(&stdfn_fact);
+  EXPECT_EQ(nullptr, grpc_event_engine::experimental::CreateEventEngine());
+}
+
+}  // namespace
+
+int main(int argc, char** argv) {
+  testing::InitGoogleTest(&argc, argv);
+  grpc::testing::TestEnvironment env(argc, argv);
+  grpc_init();
+  auto result = RUN_ALL_TESTS();
+  grpc_shutdown();
+  return result;
+}

tools/run_tests/generated/tests.json

@@ -6475,6 +6475,30 @@
     ],
     "uses_polling": true
   },
+  {
+    "args": [],
+    "benchmark": false,
+    "ci_platforms": [
+      "linux",
+      "mac",
+      "posix",
+      "windows"
+    ],
+    "cpu_cost": 1.0,
+    "exclude_configs": [],
+    "exclude_iomgrs": [],
+    "flaky": false,
+    "gtest": true,
+    "language": "c++",
+    "name": "smoke_test",
+    "platforms": [
+      "linux",
+      "mac",
+      "posix",
+      "windows"
+    ],
+    "uses_polling": true
+  },
   {
     "args": [],
     "benchmark": false,