Merge pull request #6470 from yang-g/error_with_trailer

Add a C++ test for server returning error with debug info in trailer.

src/proto/grpc/testing/echo_messages.proto

@@ -32,6 +32,12 @@ syntax = "proto3";
 
 package grpc.testing;
 
+// Message to be echoed back serialized in trailer.
+message DebugInfo {
+  repeated string stack_entries = 1;
+  string detail = 2;
+}
+
 message RequestParams {
   bool echo_deadline = 1;
   int32 client_cancel_after_us = 2;
@@ -43,6 +49,7 @@ message RequestParams {
   string expected_client_identity = 8; // will force check_auth_context.
   bool skip_cancelled_check = 9;
   string expected_transport_security_type = 10;
+  DebugInfo debug_info = 11;
 }
 
 message EchoRequest {

test/cpp/end2end/end2end_test.cc

@@ -975,6 +975,34 @@ TEST_P(End2endTest, NonExistingService) {
   EXPECT_EQ("", s.error_message());
 }
 
+// Ask the server to send back a serialized proto in trailer.
+// This is an example of setting error details.
+TEST_P(End2endTest, BinaryTrailerTest) {
+  ResetStub();
+  EchoRequest request;
+  EchoResponse response;
+  ClientContext context;
+
+  request.mutable_param()->set_echo_metadata(true);
+  DebugInfo* info = request.mutable_param()->mutable_debug_info();
+  info->add_stack_entries("stack_entry_1");
+  info->add_stack_entries("stack_entry_2");
+  info->add_stack_entries("stack_entry_3");
+  info->set_detail("detailed debug info");
+  grpc::string expected_string = info->SerializeAsString();
+  request.set_message("Hello");
+
+  Status s = stub_->Echo(&context, request, &response);
+  EXPECT_FALSE(s.ok());
+  auto trailers = context.GetServerTrailingMetadata();
+  EXPECT_EQ(1u, trailers.count(kDebugInfoTrailerKey));
+  auto iter = trailers.find(kDebugInfoTrailerKey);
+  EXPECT_EQ(expected_string, iter->second);
+  // Parse the returned trailer into a DebugInfo proto.
+  DebugInfo returned_info;
+  EXPECT_TRUE(returned_info.ParseFromString(ToString(iter->second)));
+}
+
 //////////////////////////////////////////////////////////////////////////
 // Test with and without a proxy.
 class ProxyEnd2endTest : public End2endTest {

test/cpp/end2end/test_service_impl.cc

@@ -135,6 +135,14 @@ Status TestServiceImpl::Echo(ServerContext* context, const EchoRequest* request,
       context->AddTrailingMetadata(ToString(iter->first),
                                    ToString(iter->second));
     }
+    // Terminate rpc with error and debug info in trailer.
+    if (request->param().debug_info().stack_entries_size() ||
+        !request->param().debug_info().detail().empty()) {
+      grpc::string serialized_debug_info =
+          request->param().debug_info().SerializeAsString();
+      context->AddTrailingMetadata(kDebugInfoTrailerKey, serialized_debug_info);
+      return Status::CANCELLED;
+    }
   }
   if (request->has_param() &&
       (request->param().expected_client_identity().length() > 0 ||

test/cpp/end2end/test_service_impl.h

@@ -47,6 +47,7 @@ namespace testing {
 const int kNumResponseStreamsMsgs = 3;
 const char* const kServerCancelAfterReads = "cancel_after_reads";
 const char* const kServerTryCancelRequest = "server_try_cancel";
+const char* const kDebugInfoTrailerKey = "debug-info-bin";
 
 typedef enum {
   DO_NOT_CANCEL = 0,