Command processing, validation

4 files changed, 660 insertions, 177 deletions

diff --git a/test/cpp/util/grpc_cli.cc b/test/cpp/util/grpc_cli.cc
index 53529da782..28c87956d6 100644
--- a/test/cpp/util/grpc_cli.cc
+++ b/test/cpp/util/grpc_cli.cc
@@ -34,21 +34,18 @@
 /*
   A command line tool to talk to a grpc server.
   Example of talking to grpc interop server:
-  grpc_cli call localhost:50051 UnaryCall "response_size:10" \
-      --protofiles=src/proto/grpc/testing/test.proto --enable_ssl=false
+  grpc_cli call localhost:50051 UnaryCall src/proto/grpc/testing/test.proto \
+    "response_size:10"  --enable_ssl=false
 
   Options:
-    1. --protofiles, use this flag to provide a proto file if the server does
-       does not have the reflection service.
-    2. --proto_path, if your proto file is not under current working directory,
+    1. --proto_path, if your proto file is not under current working directory,
        use this flag to provide a search root. It should work similar to the
-       counterpart in protoc. This option is valid only when protofiles is
-       provided.
-    3. --metadata specifies metadata to be sent to the server, such as:
+       counterpart in protoc.
+    2. --metadata specifies metadata to be sent to the server, such as:
        --metadata="MyHeaderKey1:Value1:MyHeaderKey2:Value2"
-    4. --enable_ssl, whether to use tls.
-    5. --use_auth, if set to true, attach a GoogleDefaultCredentials to the call
-    6. --input_binary_file, a file containing the serialized request. The file
+    3. --enable_ssl, whether to use tls.
+    4. --use_auth, if set to true, attach a GoogleDefaultCredentials to the call
+    3. --input_binary_file, a file containing the serialized request. The file
        can be generated by calling something like:
        protoc --proto_path=src/proto/grpc/testing/ \
          --encode=grpc.testing.SimpleRequest \
@@ -56,7 +53,7 @@
          < input.txt > input.bin
        If this is used and no proto file is provided in the argument list, the
        method string has to be exact in the form of /package.service/method.
-    7. --output_binary_file, a file to write binary format response into, it can
+    4. --output_binary_file, a file to write binary format response into, it can
        be later decoded using protoc:
        protoc --proto_path=src/proto/grpc/testing/ \
        --decode=grpc.testing.SimpleResponse \
@@ -64,182 +61,33 @@
        < output.bin > output.txt
 */
 
-#include <unistd.h>
 #include <fstream>
+#include <functional>
 #include <iostream>
-#include <sstream>
 
 #include <gflags/gflags.h>
-#include <grpc++/channel.h>
-#include <grpc++/create_channel.h>
-#include <grpc++/security/credentials.h>
-#include <grpc++/support/string_ref.h>
-#include <grpc/grpc.h>
-
-#include "test/cpp/util/cli_call.h"
-#include "test/cpp/util/proto_file_parser.h"
-#include "test/cpp/util/string_ref_helper.h"
+#include <grpc++/support/config.h>
+#include "test/cpp/util/grpc_tool.h"
 #include "test/cpp/util/test_config.h"
 
-DEFINE_bool(enable_ssl, true, "Whether to use ssl/tls.");
-DEFINE_bool(use_auth, false, "Whether to create default google credentials.");
-DEFINE_string(input_binary_file, "",
-              "Path to input file containing serialized request.");
-DEFINE_string(output_binary_file, "",
-              "Path to output file to write serialized response.");
-DEFINE_string(metadata, "",
-              "Metadata to send to server, in the form of key1:val1:key2:val2");
-DEFINE_string(proto_path, ".", "Path to look for the proto file.");
-// TODO(zyc): support a list of input proto files
-DEFINE_string(protofiles, "", "Name of the proto file.");
+DEFINE_string(outfile, "", "Output file (default is stdout)");
 
-void ParseMetadataFlag(
-    std::multimap<grpc::string, grpc::string>* client_metadata) {
-  if (FLAGS_metadata.empty()) {
-    return;
-  }
-  std::vector<grpc::string> fields;
-  const char* delim = ":";
-  size_t cur, next = -1;
-  do {
-    cur = next + 1;
-    next = FLAGS_metadata.find_first_of(delim, cur);
-    fields.push_back(FLAGS_metadata.substr(cur, next - cur));
-  } while (next != grpc::string::npos);
-  if (fields.size() % 2) {
-    std::cout << "Failed to parse metadata flag" << std::endl;
-    exit(1);
-  }
-  for (size_t i = 0; i < fields.size(); i += 2) {
-    client_metadata->insert(
-        std::pair<grpc::string, grpc::string>(fields[i], fields[i + 1]));
-  }
-}
-
-template <typename T>
-void PrintMetadata(const T& m, const grpc::string& message) {
-  if (m.empty()) {
-    return;
-  }
-  std::cout << message << std::endl;
-  grpc::string pair;
-  for (typename T::const_iterator iter = m.begin(); iter != m.end(); ++iter) {
-    pair.clear();
-    pair.append(iter->first.data(), iter->first.size());
-    pair.append(" : ");
-    pair.append(iter->second.data(), iter->second.size());
-    std::cout << pair << std::endl;
+static bool SimplePrint(const grpc::string& outfile,
+                        const grpc::string& output) {
+  if (outfile.empty()) {
+    std::cout << output;
+  } else {
+    std::ofstream output_file(outfile, std::ios::trunc | std::ios::binary);
+    output_file << output;
+    output_file.close();
   }
+  return true;
 }
 
 int main(int argc, char** argv) {
   grpc::testing::InitTest(&argc, &argv, true);
 
-  if (argc < 4 || grpc::string(argv[1]) != "call") {
-    std::cout << "Usage: grpc_cli call server_host:port method_name "
-              << "[proto file] [text format request] [<options>]" << std::endl;
-    return 1;
-  }
-
-  grpc::string request_text;
-  grpc::string server_address(argv[2]);
-  grpc::string method_name(argv[3]);
-  std::unique_ptr<grpc::testing::ProtoFileParser> parser;
-  grpc::string serialized_request_proto;
-
-  if (argc == 5) {
-    request_text = argv[4];
-  }
-
-  std::shared_ptr<grpc::ChannelCredentials> creds;
-  if (!FLAGS_enable_ssl) {
-    creds = grpc::InsecureChannelCredentials();
-  } else {
-    if (FLAGS_use_auth) {
-      creds = grpc::GoogleDefaultCredentials();
-    } else {
-      creds = grpc::SslCredentials(grpc::SslCredentialsOptions());
-    }
-  }
-  std::shared_ptr<grpc::Channel> channel =
-      grpc::CreateChannel(server_address, creds);
-
-  if (request_text.empty() && FLAGS_input_binary_file.empty()) {
-    if (isatty(STDIN_FILENO)) {
-      std::cout << "reading request message from stdin..." << std::endl;
-    }
-    std::stringstream input_stream;
-    input_stream << std::cin.rdbuf();
-    request_text = input_stream.str();
-  }
-
-  if (!request_text.empty()) {
-    if (!FLAGS_protofiles.empty()) {
-      parser.reset(new grpc::testing::ProtoFileParser(
-          FLAGS_proto_path, FLAGS_protofiles, method_name));
-    } else {
-      parser.reset(new grpc::testing::ProtoFileParser(channel, method_name));
-    }
-    method_name = parser->GetFullMethodName();
-    if (parser->HasError()) {
-      return 1;
-    }
-
-    if (!FLAGS_input_binary_file.empty()) {
-      std::cout
-          << "warning: request given in argv, ignoring --input_binary_file"
-          << std::endl;
-    }
-  }
-
-  if (parser) {
-    serialized_request_proto =
-        parser->GetSerializedProto(request_text, true /* is_request */);
-    if (parser->HasError()) {
-      return 1;
-    }
-  } else if (!FLAGS_input_binary_file.empty()) {
-    std::ifstream input_file(FLAGS_input_binary_file,
-                             std::ios::in | std::ios::binary);
-    std::stringstream input_stream;
-    input_stream << input_file.rdbuf();
-    serialized_request_proto = input_stream.str();
-  }
-  std::cout << "connecting to " << server_address << std::endl;
-
-  grpc::string serialized_response_proto;
-  std::multimap<grpc::string, grpc::string> client_metadata;
-  std::multimap<grpc::string_ref, grpc::string_ref> server_initial_metadata,
-      server_trailing_metadata;
-  ParseMetadataFlag(&client_metadata);
-  PrintMetadata(client_metadata, "Sending client initial metadata:");
-  grpc::Status s = grpc::testing::CliCall::Call(
-      channel, method_name, serialized_request_proto,
-      &serialized_response_proto, client_metadata, &server_initial_metadata,
-      &server_trailing_metadata);
-  PrintMetadata(server_initial_metadata,
-                "Received initial metadata from server:");
-  PrintMetadata(server_trailing_metadata,
-                "Received trailing metadata from server:");
-  if (s.ok()) {
-    std::cout << "Rpc succeeded with OK status" << std::endl;
-    if (parser) {
-      grpc::string response_text = parser->GetTextFormat(
-          serialized_response_proto, false /* is_request */);
-      if (parser->HasError()) {
-        return 1;
-      }
-      std::cout << "Response: \n " << response_text << std::endl;
-    }
-    if (!FLAGS_output_binary_file.empty()) {
-      std::ofstream output_file(FLAGS_output_binary_file,
-                                std::ios::trunc | std::ios::binary);
-      output_file << serialized_response_proto;
-    }
-  } else {
-    std::cout << "Rpc failed with status code " << s.error_code()
-              << ", error message: " << s.error_message() << std::endl;
-  }
-
-  return 0;
+  return grpc::testing::GrpcToolMainLib(
+      argc, (const char**)argv,
+      std::bind(SimplePrint, FLAGS_outfile, std::placeholders::_1));
 }
diff --git a/test/cpp/util/grpc_tool.cc b/test/cpp/util/grpc_tool.cc
new file mode 100644
index 0000000000..38ac9e55a0
--- /dev/null
+++ b/test/cpp/util/grpc_tool.cc
@@ -0,0 +1,369 @@
+/*
+ *
+ * Copyright 2016, 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.
+ *
+ */
+
+#include "grpc_tool.h"
+
+#include <unistd.h>
+#include <fstream>
+#include <iostream>
+#include <memory>
+#include <sstream>
+#include <string>
+
+#include <gflags/gflags.h>
+#include <grpc++/channel.h>
+#include <grpc++/create_channel.h>
+#include <grpc++/grpc++.h>
+#include <grpc++/security/credentials.h>
+#include <grpc++/support/string_ref.h>
+#include <grpc/grpc.h>
+#include <grpc/support/log.h>
+#include "test/cpp/util/cli_call.h"
+
+#include "test/cpp/util/proto_file_parser.h"
+#include "test/cpp/util/proto_reflection_descriptor_database.h"
+#include "test/cpp/util/string_ref_helper.h"
+#include "test/cpp/util/test_config.h"
+
+DEFINE_bool(enable_ssl, false, "Whether to use ssl/tls.");
+DEFINE_bool(use_auth, false, "Whether to create default google credentials.");
+DEFINE_string(input_binary_file, "",
+              "Path to input file containing serialized request.");
+DEFINE_string(output_binary_file, "",
+              "Path to output file to write serialized response.");
+DEFINE_string(metadata, "",
+              "Metadata to send to server, in the form of key1:val1:key2:val2");
+DEFINE_string(proto_path, ".", "Path to look for the proto file.");
+// TODO(zyc): support a list of input proto files
+DEFINE_string(protofiles, "", "Name of the proto file.");
+
+namespace grpc {
+namespace testing {
+namespace {
+
+class GrpcTool {
+ public:
+  explicit GrpcTool();
+  virtual ~GrpcTool() {}
+  bool Help(int argc, const char** argv, OutputCallback callback);
+  bool CallMethod(int argc, const char** argv, OutputCallback callback);
+  void SetPrintCommandMode(int exit_status) {
+    print_command_usage_ = true;
+    usage_exit_status_ = exit_status;
+  }
+
+ private:
+  void CommandUsage(const grpc::string& usage) const;
+  bool print_command_usage_;
+  int usage_exit_status_;
+};
+
+template <typename T>
+std::function<bool(GrpcTool*, int, const char**, OutputCallback)> BindWith4Args(
+    T&& func) {
+  return std::bind(std::forward<T>(func), std::placeholders::_1,
+                   std::placeholders::_2, std::placeholders::_3,
+                   std::placeholders::_4);
+}
+
+template <typename T>
+size_t ArraySize(T& a) {
+  return ((sizeof(a) / sizeof(*(a))) /
+          static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))));
+}
+
+void ParseMetadataFlag(
+    std::multimap<grpc::string, grpc::string>* client_metadata) {
+  if (FLAGS_metadata.empty()) {
+    return;
+  }
+  std::vector<grpc::string> fields;
+  const char* delim = ":";
+  size_t cur, next = -1;
+  do {
+    cur = next + 1;
+    next = FLAGS_metadata.find_first_of(delim, cur);
+    fields.push_back(FLAGS_metadata.substr(cur, next - cur));
+  } while (next != grpc::string::npos);
+  if (fields.size() % 2) {
+    fprintf(stderr, "Failed to parse metadata flag.\n");
+    exit(1);
+  }
+  for (size_t i = 0; i < fields.size(); i += 2) {
+    client_metadata->insert(
+        std::pair<grpc::string, grpc::string>(fields[i], fields[i + 1]));
+  }
+}
+
+template <typename T>
+void PrintMetadata(const T& m, const grpc::string& message) {
+  if (m.empty()) {
+    return;
+  }
+  fprintf(stderr, "%s\n", message.c_str());
+  grpc::string pair;
+  for (typename T::const_iterator iter = m.begin(); iter != m.end(); ++iter) {
+    pair.clear();
+    pair.append(iter->first.data(), iter->first.size());
+    pair.append(" : ");
+    pair.append(iter->second.data(), iter->second.size());
+    fprintf(stderr, "%s\n", pair.c_str());
+  }
+}
+
+struct Command {
+  const char* command;
+  std::function<bool(GrpcTool*, int, const char**, OutputCallback)> function;
+  int min_args;
+  int max_args;
+};
+
+const Command ops[] = {
+    {"help", BindWith4Args(&GrpcTool::Help), 0, INT_MAX},
+    // {"ls", BindWith4Args(&GrpcTool::ListServices), 1, 3},
+    // {"list", BindWith4Args(&GrpcTool::ListServices), 1, 3},
+    {"call", BindWith4Args(&GrpcTool::CallMethod), 2, 3},
+    // {"type", BindWith4Args(&GrpcTool::PrintType), 2, 2},
+    // {"parse", BindWith4Args(&GrpcTool::ParseMessage), 2, 3},
+    // {"totext", BindWith4Args(&GrpcTool::ToText), 2, 3},
+    // {"tobinary", BindWith4Args(&GrpcTool::ToBinary), 2, 3},
+};
+
+void Usage(const grpc::string& msg) {
+  fprintf(
+      stderr,
+      "%s\n"
+      // "  grpc_cli ls ...         ; List services\n"
+      "  grpc_cli call ...       ; Call method\n"
+      // "  grpc_cli type ...       ; Print type\n"
+      // "  grpc_cli parse ...      ; Parse message\n"
+      // "  grpc_cli totext ...     ; Convert binary message to text\n"
+      // "  grpc_cli tobinary ...   ; Convert text message to binary\n"
+      "  grpc_cli help ...       ; Print this message, or per-command usage\n"
+      "\n",
+      msg.c_str());
+
+  exit(1);
+}
+
+const Command* FindCommand(const grpc::string& name) {
+  for (int i = 0; i < (int)ArraySize(ops); i++) {
+    if (name == ops[i].command) {
+      return &ops[i];
+    }
+  }
+  return NULL;
+}
+}  // namespace
+
+int GrpcToolMainLib(int argc, const char** argv, OutputCallback callback) {
+  if (argc < 2) {
+    Usage("No command specified");
+  }
+
+  grpc::string command = argv[1];
+  argc -= 2;
+  argv += 2;
+
+  const Command* cmd = FindCommand(command);
+  if (cmd != NULL) {
+    GrpcTool grpc_tool;
+    if (argc < cmd->min_args || argc > cmd->max_args) {
+      // Force the command to print its usage message
+      fprintf(stderr, "\nWrong number of arguments for %s\n", command.c_str());
+      grpc_tool.SetPrintCommandMode(1);
+      return cmd->function(&grpc_tool, -1, NULL, callback);
+    }
+    const bool ok = cmd->function(&grpc_tool, argc, argv, callback);
+    return ok ? 0 : 1;
+  } else {
+    Usage("Invalid command '" + grpc::string(command.c_str()) + "'");
+  }
+  return 1;
+}
+
+GrpcTool::GrpcTool() : print_command_usage_(false), usage_exit_status_(0) {}
+
+void GrpcTool::CommandUsage(const grpc::string& usage) const {
+  if (print_command_usage_) {
+    fprintf(stderr, "\n%s%s\n", usage.c_str(),
+            (usage.empty() || usage[usage.size() - 1] != '\n') ? "\n" : "");
+    exit(usage_exit_status_);
+  }
+}
+
+bool GrpcTool::Help(int argc, const char** argv, OutputCallback callback) {
+  CommandUsage(
+      "Print help\n"
+      "  grpc_cli help [subcommand]\n");
+
+  if (argc == 0) {
+    Usage("");
+  } else {
+    const Command* cmd = FindCommand(argv[0]);
+    if (cmd == NULL) {
+      Usage("Unknown command '" + grpc::string(argv[0]) + "'");
+    }
+    SetPrintCommandMode(0);
+    cmd->function(this, -1, NULL, callback);
+  }
+  return true;
+}
+
+bool GrpcTool::CallMethod(int argc, const char** argv,
+                          OutputCallback callback) {
+  CommandUsage(
+      "Call method\n"
+      "  grpc_cli call <address> <service>[.<method>] <request>\n"
+      "    <address>                ; host:port\n"
+      "    <service>                ; Exported service name\n"
+      "    <method>                 ; Method name\n"
+      "    <request>                ; Text protobuffer (overrides infile)\n"
+      "    --protofiles             ; Comma separated proto files used as a"
+      " fallback when parsing request/response\n"
+      "    --proto_path             ; The search path of proto files, valid"
+      " only when --protofiles is given\n"
+      "    --metadata               ; The metadata to be sent to the server\n"
+      "    --enable_ssl             ; Set whether to use tls\n"
+      "    --use_auth               ; Set whether to create default google"
+      " credentials\n"
+      "    --outfile                ; Output filename (defaults to stdout)\n"
+      "    --input_binary_file      ; Path to input file in binary format\n"
+      "    --binary_output          ; Path to output file in binary format\n");
+
+  std::stringstream output_ss;
+  grpc::string request_text;
+  grpc::string server_address(argv[0]);
+  grpc::string method_name(argv[1]);
+  std::unique_ptr<grpc::testing::ProtoFileParser> parser;
+  grpc::string serialized_request_proto;
+
+  if (argc == 3) {
+    request_text = argv[2];
+  }
+
+  std::shared_ptr<grpc::ChannelCredentials> creds;
+  if (!FLAGS_enable_ssl) {
+    creds = grpc::InsecureChannelCredentials();
+  } else {
+    if (FLAGS_use_auth) {
+      creds = grpc::GoogleDefaultCredentials();
+    } else {
+      creds = grpc::SslCredentials(grpc::SslCredentialsOptions());
+    }
+  }
+  std::shared_ptr<grpc::Channel> channel =
+      grpc::CreateChannel(server_address, creds);
+
+  if (request_text.empty() && FLAGS_input_binary_file.empty()) {
+    if (isatty(STDIN_FILENO)) {
+      std::cout << "reading request message from stdin..." << std::endl;
+    }
+    std::stringstream input_stream;
+    input_stream << std::cin.rdbuf();
+    request_text = input_stream.str();
+  }
+
+  if (!request_text.empty()) {
+    if (!FLAGS_protofiles.empty()) {
+      parser.reset(new grpc::testing::ProtoFileParser(
+          FLAGS_proto_path, FLAGS_protofiles, method_name));
+    } else {
+      parser.reset(new grpc::testing::ProtoFileParser(channel, method_name));
+    }
+    method_name = parser->GetFullMethodName();
+    if (parser->HasError()) {
+      return 1;
+    }
+
+    if (!FLAGS_input_binary_file.empty()) {
+      std::cout
+          << "warning: request given in argv, ignoring --input_binary_file"
+          << std::endl;
+    }
+  }
+
+  if (parser) {
+    serialized_request_proto =
+        parser->GetSerializedProto(request_text, true /* is_request */);
+    if (parser->HasError()) {
+      return 1;
+    }
+  } else if (!FLAGS_input_binary_file.empty()) {
+    std::ifstream input_file(FLAGS_input_binary_file,
+                             std::ios::in | std::ios::binary);
+    std::stringstream input_stream;
+    input_stream << input_file.rdbuf();
+    serialized_request_proto = input_stream.str();
+  }
+  std::cout << "connecting to " << server_address << std::endl;
+
+  grpc::string serialized_response_proto;
+  std::multimap<grpc::string, grpc::string> client_metadata;
+  std::multimap<grpc::string_ref, grpc::string_ref> server_initial_metadata,
+      server_trailing_metadata;
+  ParseMetadataFlag(&client_metadata);
+  PrintMetadata(client_metadata, "Sending client initial metadata:");
+  grpc::Status s = grpc::testing::CliCall::Call(
+      channel, method_name, serialized_request_proto,
+      &serialized_response_proto, client_metadata, &server_initial_metadata,
+      &server_trailing_metadata);
+  PrintMetadata(server_initial_metadata,
+                "Received initial metadata from server:");
+  PrintMetadata(server_trailing_metadata,
+                "Received trailing metadata from server:");
+  if (s.ok()) {
+    std::cout << "Rpc succeeded with OK status" << std::endl;
+    if (parser) {
+      grpc::string response_text = parser->GetTextFormat(
+          serialized_response_proto, false /* is_request */);
+      if (parser->HasError()) {
+        return false;
+      }
+      output_ss << "Response: \n " << response_text << std::endl;
+    }
+    if (!FLAGS_output_binary_file.empty()) {
+      std::ofstream output_file(FLAGS_output_binary_file,
+                                std::ios::trunc | std::ios::binary);
+      output_file << serialized_response_proto;
+    }
+  } else {
+    std::cout << "Rpc failed with status code " << s.error_code()
+              << ", error message: " << s.error_message() << std::endl;
+  }
+
+  return callback(output_ss.str());
+}
+
+}  // namespace testing
+}  // namespace grpc
diff --git a/test/cpp/util/grpc_tool.h b/test/cpp/util/grpc_tool.h
new file mode 100644
index 0000000000..d779737cd5
--- /dev/null
+++ b/test/cpp/util/grpc_tool.h
@@ -0,0 +1,47 @@
+/*
+ *
+ * Copyright 2016, 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.
+ *
+ */
+
+#include <functional>
+#include <string>
+
+#include <gflags/gflags.h>
+
+namespace grpc {
+namespace testing {
+
+typedef std::function<bool(const std::string &)> OutputCallback;
+
+int GrpcToolMainLib(int argc, const char **argv, OutputCallback callback);
+
+}  // namespace testing
+}  // namespace grpc
diff --git a/test/cpp/util/grpc_tool_test.cc b/test/cpp/util/grpc_tool_test.cc
new file mode 100644
index 0000000000..77c3f3fc24
--- /dev/null
+++ b/test/cpp/util/grpc_tool_test.cc
@@ -0,0 +1,219 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "test/cpp/util/grpc_tool.h"
+
+#include <sstream>
+
+#include <grpc++/channel.h>
+#include <grpc++/client_context.h>
+#include <grpc++/create_channel.h>
+#include <grpc++/ext/proto_server_reflection_plugin.h>
+#include <grpc++/server.h>
+#include <grpc++/server_builder.h>
+#include <grpc++/server_context.h>
+#include <grpc/grpc.h>
+#include <gtest/gtest.h>
+
+#include "src/proto/grpc/testing/echo.grpc.pb.h"
+#include "src/proto/grpc/testing/echo.pb.h"
+#include "test/core/util/port.h"
+#include "test/core/util/test_config.h"
+#include "test/cpp/util/string_ref_helper.h"
+
+using grpc::testing::EchoRequest;
+using grpc::testing::EchoResponse;
+
+namespace grpc {
+namespace testing {
+
+class TestServiceImpl : public ::grpc::testing::EchoTestService::Service {
+ public:
+  Status Echo(ServerContext* context, const EchoRequest* request,
+              EchoResponse* response) GRPC_OVERRIDE {
+    if (!context->client_metadata().empty()) {
+      for (std::multimap<grpc::string_ref, grpc::string_ref>::const_iterator
+               iter = context->client_metadata().begin();
+           iter != context->client_metadata().end(); ++iter) {
+        context->AddInitialMetadata(ToString(iter->first),
+                                    ToString(iter->second));
+      }
+    }
+    context->AddTrailingMetadata("trailing_key", "trailing_value");
+    response->set_message(request->message());
+    return Status::OK;
+  }
+};
+
+class GrpcToolTest : public ::testing::Test {
+ protected:
+  GrpcToolTest() {}
+
+  void SetUp() GRPC_OVERRIDE {
+    int port = grpc_pick_unused_port_or_die();
+    server_address_ << "localhost:" << port;
+    // Setup server
+    ServerBuilder builder;
+    builder.AddListeningPort(server_address_.str(),
+                             InsecureServerCredentials());
+    builder.RegisterService(&service_);
+    server_ = builder.BuildAndStart();
+  }
+
+  void TearDown() GRPC_OVERRIDE { server_->Shutdown(); }
+
+  void ResetStub() {
+    channel_ =
+        CreateChannel(server_address_.str(), InsecureChannelCredentials());
+    stub_ = grpc::testing::EchoTestService::NewStub(channel_);
+  }
+
+  std::shared_ptr<Channel> channel_;
+  std::unique_ptr<grpc::testing::EchoTestService::Stub> stub_;
+  std::unique_ptr<Server> server_;
+  std::ostringstream server_address_;
+  TestServiceImpl service_;
+  reflection::ProtoServerReflectionPlugin plugin_;
+};
+
+static bool PrintStream(std::stringstream* ss, const grpc::string& output) {
+  (*ss) << output << std::endl;
+  return true;
+}
+
+template <typename T>
+static size_t ArraySize(T& a) {
+  return ((sizeof(a) / sizeof(*(a))) /
+          static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))));
+}
+
+#define USAGE_REGEX "(  grpc_cli .+\n){2,10}"
+
+TEST_F(GrpcToolTest, NoCommand) {
+  // Test input "grpc_cli"
+  std::stringstream output_stream;
+  const char* argv[] = {"grpc_cli"};
+  // Exit with 1, print usage instruction in stderr
+  EXPECT_EXIT(
+      GrpcToolMainLib(
+          ArraySize(argv), argv,
+          std::bind(PrintStream, &output_stream, std::placeholders::_1)),
+      ::testing::ExitedWithCode(1), "No command specified\n" USAGE_REGEX);
+  // No output
+  EXPECT_TRUE(0 == output_stream.tellp());
+}
+
+TEST_F(GrpcToolTest, InvalidCommand) {
+  // Test input "grpc_cli"
+  std::stringstream output_stream;
+  const char* argv[] = {"grpc_cli", "abc"};
+  // Exit with 1, print usage instruction in stderr
+  EXPECT_EXIT(
+      GrpcToolMainLib(
+          ArraySize(argv), argv,
+          std::bind(PrintStream, &output_stream, std::placeholders::_1)),
+      ::testing::ExitedWithCode(1), "Invalid command 'abc'\n" USAGE_REGEX);
+  // No output
+  EXPECT_TRUE(0 == output_stream.tellp());
+}
+
+TEST_F(GrpcToolTest, HelpCommand) {
+  // Test input "grpc_cli help"
+  std::stringstream output_stream;
+  const char* argv[] = {"grpc_cli", "help"};
+  // Exit with 1, print usage instruction in stderr
+  EXPECT_EXIT(GrpcToolMainLib(ArraySize(argv), argv,
+                              std::bind(PrintStream, &output_stream,
+                                        std::placeholders::_1)),
+              ::testing::ExitedWithCode(1), USAGE_REGEX);
+  // No output
+  EXPECT_TRUE(0 == output_stream.tellp());
+}
+
+TEST_F(GrpcToolTest, CallCommand) {
+  // Test input "grpc_cli call Echo"
+  std::stringstream output_stream;
+  grpc::string server_address = server_address_.str();
+  const char* argv[] = {"grpc_cli", "call", server_address.c_str(), "Echo",
+                        "message: 'Hello'"};
+
+  EXPECT_TRUE(0 == GrpcToolMainLib(ArraySize(argv), argv,
+                                   std::bind(PrintStream, &output_stream,
+                                             std::placeholders::_1)));
+  // Expected output: "message: \"Hello\""
+  EXPECT_TRUE(NULL !=
+              strstr(output_stream.str().c_str(), "message: \"Hello\""));
+}
+
+TEST_F(GrpcToolTest, TooFewArguments) {
+  // Test input "grpc_cli call localhost:<port> Echo "message: 'Hello'"
+  std::stringstream output_stream;
+  grpc::string server_address = server_address_.str();
+  const char* argv[] = {"grpc_cli", "call", "Echo"};
+
+  // Exit with 1
+  EXPECT_EXIT(
+      GrpcToolMainLib(
+          ArraySize(argv), argv,
+          std::bind(PrintStream, &output_stream, std::placeholders::_1)),
+      ::testing::ExitedWithCode(1), ".*Wrong number of arguments for call.*");
+  // No output
+  EXPECT_TRUE(0 == output_stream.tellp());
+}
+
+TEST_F(GrpcToolTest, TooManyArguments) {
+  // Test input "grpc_cli call localhost:<port> Echo Echo "message: 'Hello'"
+  std::stringstream output_stream;
+  grpc::string server_address = server_address_.str();
+  const char* argv[] = {"grpc_cli", "call", server_address.c_str(),
+                        "Echo",     "Echo", "message: 'Hello'"};
+
+  // Exit with 1
+  EXPECT_EXIT(
+      GrpcToolMainLib(
+          ArraySize(argv), argv,
+          std::bind(PrintStream, &output_stream, std::placeholders::_1)),
+      ::testing::ExitedWithCode(1), ".*Wrong number of arguments for call.*");
+  // No output
+  EXPECT_TRUE(0 == output_stream.tellp());
+}
+
+}  // namespace testing
+}  // namespace grpc
+
+int main(int argc, char** argv) {
+  grpc_test_init(argc, argv);
+  ::testing::InitGoogleTest(&argc, argv);
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  return RUN_ALL_TESTS();
+}