Use JSONEncoder to escape JSON strings.

grit/format/chrome_messages_json_unittest.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Unittest for chrome_messages_json.py.
 """
 
 import os
 import sys
@@ skipping 35 matching lines @@
 
     buf = StringIO.StringIO()
     build.RcBuilder.ProcessNode(root, DummyOutput('chrome_messages_json', 'en'), buf)
     output = buf.getvalue()
     test = u"""
 {
   "IDS_SIMPLE_MESSAGE": {
     "message": "Simple message."
   },
   "IDS_QUOTES": {
-    "message": "element\u2019s \u201c%s\u201d attribute"
+    "message": "element\\u2019s \\u201c%s\\u201d attribute"
   },
   "IDS_PLACEHOLDERS": {
     "message": "%1$d error, %2$d warning"
   },
   "IDS_STARTS_WITH_SPACE": {
     "message": "(%d)"
   },
   "IDS_DOUBLE_QUOTES": {
     "message": "A \\"double quoted\\" message."
   },
@@ skipping 12 matching lines @@
           Joi</ex></ph></message>
       </messages>
     """)
 
     buf = StringIO.StringIO()
     build.RcBuilder.ProcessNode(root, DummyOutput('chrome_messages_json', 'fr'), buf)
     output = buf.getvalue()
     test = u"""
 {
   "ID_HELLO": {
-    "message": "H\xe9P\xe9ll\xf4P\xf4!"
+    "message": "H\\u00e9P\\u00e9ll\\u00f4P\\u00f4!"
   },
   "ID_HELLO_USER": {
-    "message": "H\xe9P\xe9ll\xf4P\xf4 %s"
+    "message": "H\\u00e9P\\u00e9ll\\u00f4P\\u00f4 %s"
   }
 }
 """
     self.assertEqual(test.strip(), output.strip())
 
 
 class DummyOutput(object):
 
   def __init__(self, type, language):
     self.type = type
     self.language = language
 
   def GetType(self):
     return self.type
 
   def GetLanguage(self):
     return self.language
 
   def GetOutputFilename(self):
     return 'hello.gif'
 
 
 if __name__ == '__main__':
   unittest.main()