Add option to get only reference.

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_debugger_api.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
@@ skipping 2137 matching lines @@
   EXPECT_VALID(Dart_SetField(lib, NewString("port"), port));
 
   const String& str = String::Handle(String::New("foobar", Heap::kOld));
   Array& service_msg = Array::Handle();
   // Note: If we ever introduce old space compaction, this test might fail.
   uword start_addr = RawObject::ToAddr(str.raw());
   // Expect to find 'str', also from internal addresses.
   for (int offset = 0; offset < kObjectAlignment; ++offset) {
     uword addr = start_addr + offset;
     char buf[1024];
+    bool ref = offset % 2 == 0;
     OS::SNPrint(buf, sizeof(buf),
-                "[0, port, ['address', '%" Px "'], [], []]", addr);
+                ref ? "[0, port, ['address', '%" Px "'], ['ref'], ['true']]" :
+                      "[0, port, ['address', '%" Px "', ], [], []]",
+                addr);
     service_msg = Eval(lib, buf);
     Service::HandleIsolateMessage(isolate, service_msg);
     handler.HandleNextMessage();
-    EXPECT_SUBSTRING("\"type\":\"String\"", handler.msg());
+    EXPECT_SUBSTRING(ref ? "\"type\":\"@String\"" :
+                           "\"type\":\"String\"",
+                     handler.msg());
     EXPECT_SUBSTRING("foobar", handler.msg());
   }
   // Expect null when no object is found.
   service_msg = Eval(lib, "[0, port, ['address', '7'], [], []]");
   Service::HandleIsolateMessage(isolate, service_msg);
   handler.HandleNextMessage();
   // TODO(turnidge): Should this be a ServiceException instead?
   EXPECT_SUBSTRING("{\"type\":\"null\",\"id\":\"objects\\/null\","
                    "\"valueAsString\":\"null\"",
                handler.msg());
@@ skipping 142 matching lines @@
   service_msg = Eval(lib, "[0, port, ['profile'], ['tags'], ['hidden']]");
   Service::HandleIsolateMessage(isolate, service_msg);
   handler.HandleNextMessage();
   // Expect error.
   EXPECT_SUBSTRING("\"type\":\"Error\"", handler.msg());
 }
 
 #endif  // !defined(TARGET_ARCH_ARM64)
 
 }  // namespace dart