Allow embedder service request handlers to return JSON-RPC errors.

runtime/vm/service_test.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 
 #include "include/dart_tools_api.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
@@ skipping 553 matching lines @@
                      "['address'], ['7']]");
   Service::HandleIsolateMessage(isolate, service_msg);
   EXPECT_EQ(MessageHandler::kOK, handler.HandleNextMessage());
   // TODO(turnidge): Should this be a ServiceException instead?
   EXPECT_SUBSTRING("{\"type\":\"Sentinel\",\"kind\":\"Free\","
                    "\"valueAsString\":\"<free>\"",
                handler.msg());
 }
 
 
-static const char* alpha_callback(
+static bool alpha_callback(
     const char* name,
     const char** option_keys,
     const char** option_values,
     intptr_t num_options,
-    void* user_data) {
-  return strdup("alpha");
+    void* user_data,
+    const char** result) {
+  *result = strdup("alpha");
+  return true;
 }
 
 
-static const char* beta_callback(
+static bool beta_callback(
     const char* name,
     const char** option_keys,
     const char** option_values,
     intptr_t num_options,
-    void* user_data) {
-  return strdup("beta");
+    void* user_data,
+    const char** result) {
+  *result = strdup("beta");
+  return false;
 }
 
 
 TEST_CASE(Service_EmbedderRootHandler) {
   const char* kScript =
     "var port;\n"  // Set to our mock port by C++.
     "\n"
     "var x = 7;\n"
     "main() {\n"
     "  x = x * x;\n"
@@ skipping 18 matching lines @@
 
   Array& service_msg = Array::Handle();
   service_msg = Eval(lib, "[0, port, '\"', 'alpha', [], []]");
   Service::HandleRootMessage(service_msg);
   EXPECT_EQ(MessageHandler::kOK, handler.HandleNextMessage());
   EXPECT_STREQ("{\"jsonrpc\":\"2.0\", \"result\":alpha,\"id\":\"\\\"\"}",
                handler.msg());
   service_msg = Eval(lib, "[0, port, 1, 'beta', [], []]");
   Service::HandleRootMessage(service_msg);
   EXPECT_EQ(MessageHandler::kOK, handler.HandleNextMessage());
-  EXPECT_STREQ("{\"jsonrpc\":\"2.0\", \"result\":beta,\"id\":1}",
+  EXPECT_STREQ("{\"jsonrpc\":\"2.0\", \"error\":beta,\"id\":1}",
                handler.msg());
 }
 
 
 TEST_CASE(Service_EmbedderIsolateHandler) {
   const char* kScript =
     "var port;\n"  // Set to our mock port by C++.
     "\n"
     "var x = 7;\n"
     "main() {\n"
@@ skipping 19 matching lines @@
 
   Array& service_msg = Array::Handle();
   service_msg = Eval(lib, "[0, port, '0', 'alpha', [], []]");
   Service::HandleIsolateMessage(isolate, service_msg);
   EXPECT_EQ(MessageHandler::kOK, handler.HandleNextMessage());
   EXPECT_STREQ("{\"jsonrpc\":\"2.0\", \"result\":alpha,\"id\":\"0\"}",
                handler.msg());
   service_msg = Eval(lib, "[0, port, '0', 'beta', [], []]");
   Service::HandleIsolateMessage(isolate, service_msg);
   EXPECT_EQ(MessageHandler::kOK, handler.HandleNextMessage());
-  EXPECT_STREQ("{\"jsonrpc\":\"2.0\", \"result\":beta,\"id\":\"0\"}",
+  EXPECT_STREQ("{\"jsonrpc\":\"2.0\", \"error\":beta,\"id\":\"0\"}",
                handler.msg());
 }
 
 // TODO(zra): Remove when tests are ready to enable.
 #if !defined(TARGET_ARCH_ARM64)
 
 TEST_CASE(Service_Profile) {
   const char* kScript =
       "var port;\n"  // Set to our mock port by C++.
       "\n"
@@ skipping 37 matching lines @@
   EXPECT_EQ(MessageHandler::kOK, handler.HandleNextMessage());
   // Expect error.
   EXPECT_SUBSTRING("\"error\"", handler.msg());
 }
 
 #endif  // !defined(TARGET_ARCH_ARM64)
 
 #endif  // !PRODUCT
 
 }  // namespace dart