getObject now supports specifying offset,count for strings.

runtime/vm/json_test.cc

 // Copyright (c) 2012, 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/assert.h"
 #include "platform/text_buffer.h"
 #include "vm/json_stream.h"
 #include "vm/unit_test.h"
 #include "vm/dart_api_impl.h"
 
@@ skipping 218 matching lines @@
   String& obj = String::Handle();
 
   {
     result = Dart_GetField(lib, NewString("ascii"));
     EXPECT_VALID(result);
     obj ^= Api::UnwrapHandle(result);
 
     JSONStream js;
     {
       JSONObject jsobj(&js);
-      jsobj.AddPropertyStr("ascci", obj);;
+      EXPECT(!jsobj.AddPropertyStr("ascii", obj));
     }
-    EXPECT_STREQ("{\"ascci\":\"Hello, World!\"}", js.ToCString());
+    EXPECT_STREQ("{\"ascii\":\"Hello, World!\"}", js.ToCString());
   }
 
   {
+    result = Dart_GetField(lib, NewString("ascii"));
+    EXPECT_VALID(result);
+    obj ^= Api::UnwrapHandle(result);
+
+    JSONStream js;
+    {
+      JSONObject jsobj(&js);
+      EXPECT(jsobj.AddPropertyStr("subrange", obj, 1, 4));
+    }
+    EXPECT_STREQ("{\"subrange\":\"ello\"}", js.ToCString());
+  }
+
+  {
     result = Dart_GetField(lib, NewString("unicode"));
     EXPECT_VALID(result);
     obj ^= Api::UnwrapHandle(result);
 
     JSONStream js;
     {
       JSONObject jsobj(&js);
-      jsobj.AddPropertyStr("unicode", obj);
+      EXPECT(!jsobj.AddPropertyStr("unicode", obj));
     }
     EXPECT_STREQ("{\"unicode\":\"\\u00CE\\u00F1\\u0163\\u00E9r\\u00F1\\u00E5"
                  "\\u0163\\u00EE\\u00F6\\u00F1\\u00E5\\u013C\\u00EE\\u017E"
                  "\\u00E5\\u0163\\u00EE\\u1EDD\\u00F1\"}", js.ToCString());
   }
 
   {
     result = Dart_GetField(lib, NewString("surrogates"));
     EXPECT_VALID(result);
     obj ^= Api::UnwrapHandle(result);
 
     JSONStream js;
     {
       JSONObject jsobj(&js);
-      jsobj.AddPropertyStr("surrogates", obj);
+      EXPECT(!jsobj.AddPropertyStr("surrogates", obj));
     }
     EXPECT_STREQ("{\"surrogates\":\"\\uD834\\uDD1E\\uD834\\uDD1E\\uD834\\uDD1E"
                  "\\uD834\\uDD1E\\uD834\\uDD1E\"}", js.ToCString());
   }
 
   {
     result = Dart_GetField(lib, NewString("nullInMiddle"));
     EXPECT_VALID(result);
     obj ^= Api::UnwrapHandle(result);
 
     JSONStream js;
     {
       JSONObject jsobj(&js);
-      jsobj.AddPropertyStr("nullInMiddle", obj);
+      EXPECT(!jsobj.AddPropertyStr("nullInMiddle", obj));
     }
     EXPECT_STREQ("{\"nullInMiddle\":\"This has\\u0000 four words.\"}",
                  js.ToCString());
   }
 }
 
 
 TEST_CASE(JSON_JSONStream_Params) {
   const char* param_keys[] = {"dog", "cat"};
   const char* param_values[] = {"apple", "banana"};
 
   JSONStream js;
   EXPECT(js.num_params() == 0);
   js.SetParams(&param_keys[0], &param_values[0], 2);
   EXPECT(js.num_params() == 2);
   EXPECT(!js.HasParam("lizard"));
   EXPECT(js.HasParam("dog"));
   EXPECT(js.HasParam("cat"));
   EXPECT(js.ParamIs("cat", "banana"));
   EXPECT(!js.ParamIs("dog", "banana"));
 }
 
 }  // namespace dart