getObject now supports specifying offset,count for strings.

runtime/observatory/tests/service/get_object_rpc_test.dart

 // Copyright (c) 2015, 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.
 // VMOptions=--error_on_bad_type --error_on_bad_override
 
 library get_object_rpc_test;
 
 import 'dart:typed_data';
 import 'dart:convert' show BASE64;
 import 'package:observatory/service_io.dart';
@@ skipping 68 matching lines @@
     expect(result['kind'], equals('Int'));
     expect(result['_vmType'], equals('Smi'));
     expect(result['id'], equals('objects/int-123'));
     expect(result['valueAsString'], equals('123'));
     expect(result['class']['type'], equals('@Class'));
     expect(result['class']['name'], equals('_Smi'));
     expect(result['size'], isZero);
     expect(result['fields'], isEmpty);
   },
 
+  // A string
+  (Isolate isolate) async {
+    // Call eval to get a Dart list.
+    var evalResult = await eval(isolate, '"Chattanooga"');
+    var params = {
+      'objectId': evalResult['id'],
+    };
+    var result = await isolate.invokeRpcNoUpgrade('getObject', params);
+    expect(result['type'], equals('Instance'));
+    expect(result['kind'], equals('String'));
+    expect(result['_vmType'], equals('String'));
+    expect(result['id'], startsWith('objects/'));
+    expect(result['valueAsString'], equals('Chattanooga'));
+    expect(result['class']['type'], equals('@Class'));
+    expect(result['class']['name'], equals('_OneByteString'));
+    expect(result['size'], isPositive);
+    expect(result['fields'], isEmpty);
+    expect(result['length'], equals(11));
+    expect(result['offset'], isNull);
+    expect(result['count'], isNull);
+  },
+
+  // String prefix.
+  (Isolate isolate) async {
+    // Call eval to get a Dart list.
+    var evalResult = await eval(isolate, '"Chattanooga"');
+    var params = {
+      'objectId': evalResult['id'],
+      'count': 4,
+    };
+    var result = await isolate.invokeRpcNoUpgrade('getObject', params);
+    expect(result['type'], equals('Instance'));
+    expect(result['kind'], equals('String'));
+    expect(result['_vmType'], equals('String'));
+    expect(result['id'], startsWith('objects/'));
+    expect(result['valueAsString'], equals('Chat'));
+    expect(result['class']['type'], equals('@Class'));
+    expect(result['class']['name'], equals('_OneByteString'));
+    expect(result['size'], isPositive);
+    expect(result['fields'], isEmpty);
+    expect(result['length'], equals(11));
+    expect(result['offset'], isNull);
+    expect(result['count'], equals(4));
+  },
+
+  // String subrange.
+  (Isolate isolate) async {
+    // Call eval to get a Dart list.
+    var evalResult = await eval(isolate, '"Chattanooga"');
+    var params = {
+      'objectId': evalResult['id'],
+      'offset': 4,
+      'count': 6,
+    };
+    var result = await isolate.invokeRpcNoUpgrade('getObject', params);
+    expect(result['type'], equals('Instance'));
+    expect(result['kind'], equals('String'));
+    expect(result['_vmType'], equals('String'));
+    expect(result['id'], startsWith('objects/'));
+    expect(result['valueAsString'], equals('tanoog'));
+    expect(result['class']['type'], equals('@Class'));
+    expect(result['class']['name'], equals('_OneByteString'));
+    expect(result['size'], isPositive);
+    expect(result['fields'], isEmpty);
+    expect(result['length'], equals(11));
+    expect(result['offset'], equals(4));
+    expect(result['count'], equals(6));
+  },
+
+  // String with wacky offset.
+  (Isolate isolate) async {
+    // Call eval to get a Dart list.
+    var evalResult = await eval(isolate, '"Chattanooga"');
+    var params = {
+      'objectId': evalResult['id'],
+      'offset': 100,
+      'count': 2,
+    };
+    var result = await isolate.invokeRpcNoUpgrade('getObject', params);
+    expect(result['type'], equals('Instance'));
+    expect(result['kind'], equals('String'));
+    expect(result['_vmType'], equals('String'));
+    expect(result['id'], startsWith('objects/'));
+    expect(result['valueAsString'], equals(''));
+    expect(result['class']['type'], equals('@Class'));
+    expect(result['class']['name'], equals('_OneByteString'));
+    expect(result['size'], isPositive);
+    expect(result['fields'], isEmpty);
+    expect(result['length'], equals(11));
+    expect(result['offset'], equals(11));
+    expect(result['count'], equals(0));
+  },
+
   // A built-in List.
   (Isolate isolate) async {
     // Call eval to get a Dart list.
     var evalResult = await eval(isolate, '[3, 2, 1]');
     var params = {
       'objectId': evalResult['id'],
     };
     var result = await isolate.invokeRpcNoUpgrade('getObject', params);
     expect(result['type'], equals('Instance'));
     expect(result['kind'], equals('List'));
@@ skipping 755 matching lines @@
       caughtException = true;
       expect(e.code, equals(ServerRpcException.kInvalidParams));
       expect(e.message,
              "getObject: invalid 'objectId' parameter: code/0");
     }
     expect(caughtException, isTrue);
   },
 ];
 
 main(args) async => runIsolateTests(args, tests, testeeBefore:warmup);