Regenerate files, fix bugs

15 files changed, 159 insertions, 48 deletions

diff --git a/test/core/end2end/end2end_nosec_tests.c b/test/core/end2end/end2end_nosec_tests.c
index 9ff46d62e4..17dc190d14 100644
--- a/test/core/end2end/end2end_nosec_tests.c
+++ b/test/core/end2end/end2end_nosec_tests.c
@@ -46,9 +46,8 @@ extern void cancel_after_invoke(grpc_end2end_test_config config);
 extern void cancel_before_invoke(grpc_end2end_test_config config);
 extern void cancel_in_a_vacuum(grpc_end2end_test_config config);
 extern void cancel_with_status(grpc_end2end_test_config config);
-extern void channel_connectivity(grpc_end2end_test_config config);
-extern void channel_ping(grpc_end2end_test_config config);
 extern void compressed_payload(grpc_end2end_test_config config);
+extern void connectivity(grpc_end2end_test_config config);
 extern void default_host(grpc_end2end_test_config config);
 extern void disappearing_server(grpc_end2end_test_config config);
 extern void empty_batch(grpc_end2end_test_config config);
@@ -59,10 +58,10 @@ extern void invoke_large_request(grpc_end2end_test_config config);
 extern void large_metadata(grpc_end2end_test_config config);
 extern void max_concurrent_streams(grpc_end2end_test_config config);
 extern void max_message_length(grpc_end2end_test_config config);
-extern void metadata(grpc_end2end_test_config config);
 extern void negative_deadline(grpc_end2end_test_config config);
 extern void no_op(grpc_end2end_test_config config);
 extern void payload(grpc_end2end_test_config config);
+extern void ping(grpc_end2end_test_config config);
 extern void ping_pong_streaming(grpc_end2end_test_config config);
 extern void registered_call(grpc_end2end_test_config config);
 extern void request_with_flags(grpc_end2end_test_config config);
@@ -71,6 +70,7 @@ extern void server_finishes_request(grpc_end2end_test_config config);
 extern void shutdown_finishes_calls(grpc_end2end_test_config config);
 extern void shutdown_finishes_tags(grpc_end2end_test_config config);
 extern void simple_delayed_request(grpc_end2end_test_config config);
+extern void simple_metadata(grpc_end2end_test_config config);
 extern void simple_request(grpc_end2end_test_config config);
 extern void trailing_metadata(grpc_end2end_test_config config);
 
@@ -87,9 +87,8 @@ void grpc_end2end_tests(int argc, char **argv,
     cancel_before_invoke(config);
     cancel_in_a_vacuum(config);
     cancel_with_status(config);
-    channel_connectivity(config);
-    channel_ping(config);
     compressed_payload(config);
+    connectivity(config);
     default_host(config);
     disappearing_server(config);
     empty_batch(config);
@@ -100,10 +99,10 @@ void grpc_end2end_tests(int argc, char **argv,
     large_metadata(config);
     max_concurrent_streams(config);
     max_message_length(config);
-    metadata(config);
     negative_deadline(config);
     no_op(config);
     payload(config);
+    ping(config);
     ping_pong_streaming(config);
     registered_call(config);
     request_with_flags(config);
@@ -112,6 +111,7 @@ void grpc_end2end_tests(int argc, char **argv,
     shutdown_finishes_calls(config);
     shutdown_finishes_tags(config);
     simple_delayed_request(config);
+    simple_metadata(config);
     simple_request(config);
     trailing_metadata(config);
     return;
@@ -150,18 +150,14 @@ void grpc_end2end_tests(int argc, char **argv,
       cancel_with_status(config);
       continue;
     }
-    if (0 == strcmp("channel_connectivity", argv[i])) {
-      channel_connectivity(config);
-      continue;
-    }
-    if (0 == strcmp("channel_ping", argv[i])) {
-      channel_ping(config);
-      continue;
-    }
     if (0 == strcmp("compressed_payload", argv[i])) {
       compressed_payload(config);
       continue;
     }
+    if (0 == strcmp("connectivity", argv[i])) {
+      connectivity(config);
+      continue;
+    }
     if (0 == strcmp("default_host", argv[i])) {
       default_host(config);
       continue;
@@ -202,10 +198,6 @@ void grpc_end2end_tests(int argc, char **argv,
       max_message_length(config);
       continue;
     }
-    if (0 == strcmp("metadata", argv[i])) {
-      metadata(config);
-      continue;
-    }
     if (0 == strcmp("negative_deadline", argv[i])) {
       negative_deadline(config);
       continue;
@@ -218,6 +210,10 @@ void grpc_end2end_tests(int argc, char **argv,
       payload(config);
       continue;
     }
+    if (0 == strcmp("ping", argv[i])) {
+      ping(config);
+      continue;
+    }
     if (0 == strcmp("ping_pong_streaming", argv[i])) {
       ping_pong_streaming(config);
       continue;
@@ -250,6 +246,10 @@ void grpc_end2end_tests(int argc, char **argv,
       simple_delayed_request(config);
       continue;
     }
+    if (0 == strcmp("simple_metadata", argv[i])) {
+      simple_metadata(config);
+      continue;
+    }
     if (0 == strcmp("simple_request", argv[i])) {
       simple_request(config);
       continue;
diff --git a/test/core/end2end/end2end_tests.c b/test/core/end2end/end2end_tests.c
index 397ff446a9..6f2f5aff78 100644
--- a/test/core/end2end/end2end_tests.c
+++ b/test/core/end2end/end2end_tests.c
@@ -47,9 +47,8 @@ extern void cancel_after_invoke(grpc_end2end_test_config config);
 extern void cancel_before_invoke(grpc_end2end_test_config config);
 extern void cancel_in_a_vacuum(grpc_end2end_test_config config);
 extern void cancel_with_status(grpc_end2end_test_config config);
-extern void channel_connectivity(grpc_end2end_test_config config);
-extern void channel_ping(grpc_end2end_test_config config);
 extern void compressed_payload(grpc_end2end_test_config config);
+extern void connectivity(grpc_end2end_test_config config);
 extern void default_host(grpc_end2end_test_config config);
 extern void disappearing_server(grpc_end2end_test_config config);
 extern void empty_batch(grpc_end2end_test_config config);
@@ -60,10 +59,10 @@ extern void invoke_large_request(grpc_end2end_test_config config);
 extern void large_metadata(grpc_end2end_test_config config);
 extern void max_concurrent_streams(grpc_end2end_test_config config);
 extern void max_message_length(grpc_end2end_test_config config);
-extern void metadata(grpc_end2end_test_config config);
 extern void negative_deadline(grpc_end2end_test_config config);
 extern void no_op(grpc_end2end_test_config config);
 extern void payload(grpc_end2end_test_config config);
+extern void ping(grpc_end2end_test_config config);
 extern void ping_pong_streaming(grpc_end2end_test_config config);
 extern void registered_call(grpc_end2end_test_config config);
 extern void request_with_flags(grpc_end2end_test_config config);
@@ -72,6 +71,7 @@ extern void server_finishes_request(grpc_end2end_test_config config);
 extern void shutdown_finishes_calls(grpc_end2end_test_config config);
 extern void shutdown_finishes_tags(grpc_end2end_test_config config);
 extern void simple_delayed_request(grpc_end2end_test_config config);
+extern void simple_metadata(grpc_end2end_test_config config);
 extern void simple_request(grpc_end2end_test_config config);
 extern void trailing_metadata(grpc_end2end_test_config config);
 
@@ -89,9 +89,8 @@ void grpc_end2end_tests(int argc, char **argv,
     cancel_before_invoke(config);
     cancel_in_a_vacuum(config);
     cancel_with_status(config);
-    channel_connectivity(config);
-    channel_ping(config);
     compressed_payload(config);
+    connectivity(config);
     default_host(config);
     disappearing_server(config);
     empty_batch(config);
@@ -102,10 +101,10 @@ void grpc_end2end_tests(int argc, char **argv,
     large_metadata(config);
     max_concurrent_streams(config);
     max_message_length(config);
-    metadata(config);
     negative_deadline(config);
     no_op(config);
     payload(config);
+    ping(config);
     ping_pong_streaming(config);
     registered_call(config);
     request_with_flags(config);
@@ -114,6 +113,7 @@ void grpc_end2end_tests(int argc, char **argv,
     shutdown_finishes_calls(config);
     shutdown_finishes_tags(config);
     simple_delayed_request(config);
+    simple_metadata(config);
     simple_request(config);
     trailing_metadata(config);
     return;
@@ -156,18 +156,14 @@ void grpc_end2end_tests(int argc, char **argv,
       cancel_with_status(config);
       continue;
     }
-    if (0 == strcmp("channel_connectivity", argv[i])) {
-      channel_connectivity(config);
-      continue;
-    }
-    if (0 == strcmp("channel_ping", argv[i])) {
-      channel_ping(config);
-      continue;
-    }
     if (0 == strcmp("compressed_payload", argv[i])) {
       compressed_payload(config);
       continue;
     }
+    if (0 == strcmp("connectivity", argv[i])) {
+      connectivity(config);
+      continue;
+    }
     if (0 == strcmp("default_host", argv[i])) {
       default_host(config);
       continue;
@@ -208,10 +204,6 @@ void grpc_end2end_tests(int argc, char **argv,
       max_message_length(config);
       continue;
     }
-    if (0 == strcmp("metadata", argv[i])) {
-      metadata(config);
-      continue;
-    }
     if (0 == strcmp("negative_deadline", argv[i])) {
       negative_deadline(config);
       continue;
@@ -224,6 +216,10 @@ void grpc_end2end_tests(int argc, char **argv,
       payload(config);
       continue;
     }
+    if (0 == strcmp("ping", argv[i])) {
+      ping(config);
+      continue;
+    }
     if (0 == strcmp("ping_pong_streaming", argv[i])) {
       ping_pong_streaming(config);
       continue;
@@ -256,6 +252,10 @@ void grpc_end2end_tests(int argc, char **argv,
       simple_delayed_request(config);
       continue;
     }
+    if (0 == strcmp("simple_metadata", argv[i])) {
+      simple_metadata(config);
+      continue;
+    }
     if (0 == strcmp("simple_request", argv[i])) {
       simple_request(config);
       continue;
diff --git a/test/core/end2end/fixtures/h2_ssl+poll.c b/test/core/end2end/fixtures/h2_ssl+poll.c
index 0d489d62e2..02bf16642d 100644
--- a/test/core/end2end/fixtures/h2_ssl+poll.c
+++ b/test/core/end2end/fixtures/h2_ssl+poll.c
@@ -43,7 +43,7 @@
 #include "src/core/channel/channel_args.h"
 #include "src/core/security/credentials.h"
 #include "src/core/support/env.h"
-#include "src/core/support/load_file.h"
+#include "src/core/support/tmpfile.h"
 #include "src/core/support/string.h"
 #include "test/core/end2end/data/ssl_test_data.h"
 #include "test/core/util/port.h"
diff --git a/test/core/end2end/fixtures/h2_ssl.c b/test/core/end2end/fixtures/h2_ssl.c
index 187399cad1..04bfb70303 100644
--- a/test/core/end2end/fixtures/h2_ssl.c
+++ b/test/core/end2end/fixtures/h2_ssl.c
@@ -43,7 +43,7 @@
 #include "src/core/channel/channel_args.h"
 #include "src/core/security/credentials.h"
 #include "src/core/support/env.h"
-#include "src/core/support/load_file.h"
+#include "src/core/support/tmpfile.h"
 #include "src/core/support/string.h"
 #include "test/core/end2end/data/ssl_test_data.h"
 #include "test/core/util/port.h"
diff --git a/test/core/end2end/fixtures/h2_ssl_proxy.c b/test/core/end2end/fixtures/h2_ssl_proxy.c
index dc758061f8..5288318a83 100644
--- a/test/core/end2end/fixtures/h2_ssl_proxy.c
+++ b/test/core/end2end/fixtures/h2_ssl_proxy.c
@@ -43,7 +43,7 @@
 #include "src/core/channel/channel_args.h"
 #include "src/core/security/credentials.h"
 #include "src/core/support/env.h"
-#include "src/core/support/load_file.h"
+#include "src/core/support/tmpfile.h"
 #include "src/core/support/string.h"
 #include "test/core/end2end/data/ssl_test_data.h"
 #include "test/core/end2end/fixtures/proxy.h"
diff --git a/test/core/end2end/tests/connectivity.c b/test/core/end2end/tests/connectivity.c
index 0e21e65557..edef2ff68b 100644
--- a/test/core/end2end/tests/connectivity.c
+++ b/test/core/end2end/tests/connectivity.c
@@ -168,7 +168,7 @@ static void test_connectivity(grpc_end2end_test_config config) {
   cq_verifier_destroy(cqv);
 }
 
-void channel_connectivity(grpc_end2end_test_config config) {
+void connectivity(grpc_end2end_test_config config) {
   GPR_ASSERT(config.feature_mask & FEATURE_MASK_SUPPORTS_DELAYED_CONNECTION);
   test_connectivity(config);
 }
diff --git a/test/core/end2end/tests/ping.c b/test/core/end2end/tests/ping.c
index 73fab206fb..f42f186502 100644
--- a/test/core/end2end/tests/ping.c
+++ b/test/core/end2end/tests/ping.c
@@ -91,7 +91,7 @@ static void test_ping(grpc_end2end_test_config config) {
   cq_verifier_destroy(cqv);
 }
 
-void channel_ping(grpc_end2end_test_config config) {
+void ping(grpc_end2end_test_config config) {
   GPR_ASSERT(config.feature_mask & FEATURE_MASK_SUPPORTS_DELAYED_CONNECTION);
   test_ping(config);
 }
diff --git a/test/core/end2end/tests/simple_metadata.c b/test/core/end2end/tests/simple_metadata.c
index 5e92091eb7..376ffb670a 100644
--- a/test/core/end2end/tests/simple_metadata.c
+++ b/test/core/end2end/tests/simple_metadata.c
@@ -260,6 +260,6 @@ static void test_request_response_with_metadata_and_payload(
   config.tear_down_data(&f);
 }
 
-void metadata(grpc_end2end_test_config config) {
+void simple_metadata(grpc_end2end_test_config config) {
   test_request_response_with_metadata_and_payload(config);
 }
diff --git a/test/core/security/credentials_test.c b/test/core/security/credentials_test.c
index 2c3d4cd0d6..98133ef5e5 100644
--- a/test/core/security/credentials_test.c
+++ b/test/core/security/credentials_test.c
@@ -47,7 +47,7 @@
 #include "src/core/httpcli/httpcli.h"
 #include "src/core/security/json_token.h"
 #include "src/core/support/env.h"
-#include "src/core/support/load_file.h"
+#include "src/core/support/tmpfile.h"
 #include "src/core/support/string.h"
 #include "test/core/util/test_config.h"
 
diff --git a/test/core/security/security_connector_test.c b/test/core/security/security_connector_test.c
index edb45b6680..420e3a4c52 100644
--- a/test/core/security/security_connector_test.c
+++ b/test/core/security/security_connector_test.c
@@ -43,7 +43,7 @@
 #include "src/core/security/security_connector.h"
 #include "src/core/security/security_context.h"
 #include "src/core/support/env.h"
-#include "src/core/support/load_file.h"
+#include "src/core/support/tmpfile.h"
 #include "src/core/support/string.h"
 #include "src/core/tsi/ssl_transport_security.h"
 #include "src/core/tsi/transport_security.h"
diff --git a/test/core/support/load_file_test.c b/test/core/support/load_file_test.c
index 59d6ba8912..9ba0dc80a1 100644
--- a/test/core/support/load_file_test.c
+++ b/test/core/support/load_file_test.c
@@ -39,6 +39,7 @@
 #include <grpc/support/slice.h>
 
 #include "src/core/support/load_file.h"
+#include "src/core/support/tmpfile.h"
 #include "src/core/support/string.h"
 #include "test/core/util/test_config.h"
 
diff --git a/test/cpp/interop/client.cc b/test/cpp/interop/client.cc
index cb9b396beb..788adefd24 100644
--- a/test/cpp/interop/client.cc
+++ b/test/cpp/interop/client.cc
@@ -1,6 +1,6 @@
 /*
  *
- * Copyright 2015, Google Inc.
+ * Copyright 2015-2016, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -74,6 +74,7 @@ DEFINE_string(test_case, "large_unary",
               "oauth2_auth_token: raw oauth2 access token auth; "
               "per_rpc_creds: raw oauth2 access token on a single rpc; "
               "status_code_and_message: verify status code & message; "
+              "custom_metadata: server will echo custom metadata;"
               "all : all of above.");
 DEFINE_string(default_service_account, "",
               "Email of GCE default service account");
@@ -129,6 +130,8 @@ int main(int argc, char** argv) {
     client.DoPerRpcCreds(json_key);
   } else if (FLAGS_test_case == "status_code_and_message") {
     client.DoStatusWithMessage();
+  } else if (FLAGS_test_case == "custom_metadata") {
+    client.DoCustomMetadata();
   } else if (FLAGS_test_case == "all") {
     client.DoEmpty();
     client.DoLargeUnary();
@@ -142,6 +145,7 @@ int main(int argc, char** argv) {
     client.DoTimeoutOnSleepingServer();
     client.DoEmptyStream();
     client.DoStatusWithMessage();
+    client.DoCustomMetadata();
     // service_account_creds and jwt_token_creds can only run with ssl.
     if (FLAGS_use_tls) {
       grpc::string json_key = GetServiceAccountJsonKey();
@@ -159,7 +163,7 @@ int main(int argc, char** argv) {
         "server_compressed_streaming|half_duplex|ping_pong|cancel_after_begin|"
         "cancel_after_first_response|timeout_on_sleeping_server|empty_stream|"
         "compute_engine_creds|jwt_token_creds|oauth2_auth_token|per_rpc_creds",
-        FLAGS_test_case.c_str());
+        "status_code_and_message|custom_metadata", FLAGS_test_case.c_str());
     ret = 1;
   }
 
diff --git a/test/cpp/interop/interop_client.cc b/test/cpp/interop/interop_client.cc
index b06310781a..46f6fdac40 100644
--- a/test/cpp/interop/interop_client.cc
+++ b/test/cpp/interop/interop_client.cc
@@ -625,5 +625,77 @@ void InteropClient::DoStatusWithMessage() {
   gpr_log(GPR_DEBUG, "Done testing Status and Message");
 }
 
+void InteropClient::DoCustomMetadata() {
+  const grpc::string kEchoInitialMetadataKey("x-grpc-test-echo-initial");
+  const grpc::string kInitialMetadataValue("test_initial_metadata_value");
+  const grpc::string kEchoTrailingBinMetadataKey(
+      "x-grpc-test-echo-trailing-bin");
+  const grpc::string kTrailingBinValue("\x0a\x0b\x0a\x0b\x0a\x0b");
+  ;
+
+  {
+    gpr_log(GPR_DEBUG, "Sending RPC with custom metadata");
+    ClientContext context;
+    context.AddMetadata(kEchoInitialMetadataKey, kInitialMetadataValue);
+    context.AddMetadata(kEchoTrailingBinMetadataKey, kTrailingBinValue);
+    SimpleRequest request;
+    SimpleResponse response;
+    request.set_response_size(kLargeResponseSize);
+    grpc::string payload(kLargeRequestSize, '\0');
+    request.mutable_payload()->set_body(payload.c_str(), kLargeRequestSize);
+
+    Status s = serviceStub_.Get()->UnaryCall(&context, request, &response);
+    AssertOkOrPrintErrorStatus(s);
+    const auto& server_initial_metadata = context.GetServerInitialMetadata();
+    auto iter = server_initial_metadata.find(kEchoInitialMetadataKey);
+    GPR_ASSERT(iter != server_initial_metadata.end());
+    GPR_ASSERT(iter->second.data() == kInitialMetadataValue);
+    const auto& server_trailing_metadata = context.GetServerTrailingMetadata();
+    iter = server_trailing_metadata.find(kEchoTrailingBinMetadataKey);
+    GPR_ASSERT(iter != server_trailing_metadata.end());
+    GPR_ASSERT(grpc::string(iter->second.begin(), iter->second.end()) ==
+               kTrailingBinValue);
+
+    gpr_log(GPR_DEBUG, "Done testing RPC with custom metadata");
+  }
+
+  {
+    gpr_log(GPR_DEBUG, "Sending stream with custom metadata");
+    ClientContext context;
+    context.AddMetadata(kEchoInitialMetadataKey, kInitialMetadataValue);
+    context.AddMetadata(kEchoTrailingBinMetadataKey, kTrailingBinValue);
+    std::unique_ptr<ClientReaderWriter<StreamingOutputCallRequest,
+                                       StreamingOutputCallResponse>>
+        stream(serviceStub_.Get()->FullDuplexCall(&context));
+
+    StreamingOutputCallRequest request;
+    request.set_response_type(PayloadType::COMPRESSABLE);
+    ResponseParameters* response_parameter = request.add_response_parameters();
+    response_parameter->set_size(kLargeResponseSize);
+    grpc::string payload(kLargeRequestSize, '\0');
+    request.mutable_payload()->set_body(payload.c_str(), kLargeRequestSize);
+    StreamingOutputCallResponse response;
+    GPR_ASSERT(stream->Write(request));
+    stream->WritesDone();
+    GPR_ASSERT(stream->Read(&response));
+    GPR_ASSERT(response.payload().body() ==
+               grpc::string(kLargeResponseSize, '\0'));
+    GPR_ASSERT(!stream->Read(&response));
+    Status s = stream->Finish();
+    AssertOkOrPrintErrorStatus(s);
+    const auto& server_initial_metadata = context.GetServerInitialMetadata();
+    auto iter = server_initial_metadata.find(kEchoInitialMetadataKey);
+    GPR_ASSERT(iter != server_initial_metadata.end());
+    GPR_ASSERT(iter->second.data() == kInitialMetadataValue);
+    const auto& server_trailing_metadata = context.GetServerTrailingMetadata();
+    iter = server_trailing_metadata.find(kEchoTrailingBinMetadataKey);
+    GPR_ASSERT(iter != server_trailing_metadata.end());
+    GPR_ASSERT(grpc::string(iter->second.begin(), iter->second.end()) ==
+               kTrailingBinValue);
+
+    gpr_log(GPR_DEBUG, "Done testing stream with custom metadata");
+  }
+}
+
 }  // namespace testing
 }  // namespace grpc
diff --git a/test/cpp/interop/interop_client.h b/test/cpp/interop/interop_client.h
index 3ecd380398..3f57f3c733 100644
--- a/test/cpp/interop/interop_client.h
+++ b/test/cpp/interop/interop_client.h
@@ -1,6 +1,6 @@
 /*
  *
- * Copyright 2015, Google Inc.
+ * Copyright 2015-2016, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -75,6 +75,7 @@ class InteropClient {
   void DoTimeoutOnSleepingServer();
   void DoEmptyStream();
   void DoStatusWithMessage();
+  void DoCustomMetadata();
   // Auth tests.
   // username is a string containing the user email
   void DoJwtTokenCreds(const grpc::string& username);
diff --git a/test/cpp/interop/server_main.cc b/test/cpp/interop/server_main.cc
index cdca060c23..18ac35d551 100644
--- a/test/cpp/interop/server_main.cc
+++ b/test/cpp/interop/server_main.cc
@@ -1,6 +1,6 @@
 /*
  *
- * Copyright 2015, Google Inc.
+ * Copyright 2015-2016, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -80,6 +80,36 @@ using grpc::Status;
 static bool got_sigint = false;
 static const char* kRandomFile = "test/cpp/interop/rnd.dat";
 
+const char kEchoInitialMetadataKey[] = "x-grpc-test-echo-initial";
+const char kEchoTrailingBinMetadataKey[] = "x-grpc-test-echo-trailing-bin";
+const char kEchoUserAgentKey[] = "x-grpc-test-echo-useragent";
+
+void MaybeEchoMetadata(ServerContext* context) {
+  const auto& client_metadata = context->client_metadata();
+  GPR_ASSERT(client_metadata.count(kEchoInitialMetadataKey) <= 1);
+  GPR_ASSERT(client_metadata.count(kEchoTrailingBinMetadataKey) <= 1);
+
+  auto iter = client_metadata.find(kEchoInitialMetadataKey);
+  if (iter != client_metadata.end()) {
+    context->AddInitialMetadata(kEchoInitialMetadataKey, iter->second.data());
+  }
+  iter = client_metadata.find(kEchoTrailingBinMetadataKey);
+  if (iter != client_metadata.end()) {
+    context->AddTrailingMetadata(
+        kEchoTrailingBinMetadataKey,
+        grpc::string(iter->second.begin(), iter->second.end()));
+  }
+  // Check if client sent a magic key in the header that makes us echo
+  // back the user-agent (for testing purpose)
+  iter = client_metadata.find(kEchoUserAgentKey);
+  if (iter != client_metadata.end()) {
+    iter = client_metadata.find("user-agent");
+    if (iter != client_metadata.end()) {
+      context->AddInitialMetadata(kEchoUserAgentKey, iter->second.data());
+    }
+  }
+}
+
 bool SetPayload(PayloadType type, int size, Payload* payload) {
   PayloadType response_type;
   if (type == PayloadType::RANDOM) {
@@ -130,11 +160,13 @@ class TestServiceImpl : public TestService::Service {
  public:
   Status EmptyCall(ServerContext* context, const grpc::testing::Empty* request,
                    grpc::testing::Empty* response) {
+    MaybeEchoMetadata(context);
     return Status::OK;
   }
 
   Status UnaryCall(ServerContext* context, const SimpleRequest* request,
                    SimpleResponse* response) {
+    MaybeEchoMetadata(context);
     SetResponseCompression(context, *request);
     if (request->response_size() > 0) {
       if (!SetPayload(request->response_type(), request->response_size(),
@@ -192,6 +224,7 @@ class TestServiceImpl : public TestService::Service {
       ServerContext* context,
       ServerReaderWriter<StreamingOutputCallResponse,
                          StreamingOutputCallRequest>* stream) {
+    MaybeEchoMetadata(context);
     StreamingOutputCallRequest request;
     StreamingOutputCallResponse response;
     bool write_success = true;