Allow substitution of messages as variables in other messages.

grit/format/policy_templates/writers/writer_unittest_common.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.
 
 '''Common tools for unit-testing writers.'''
 
 
 import os
 import sys
@@ skipping 43 matching lines @@
     <grit base_dir="." latest_public_release="0" current_release="1" source_lang_id="en">
       <release seq="1">
         <structures>
           <structure name="IDD_POLICY_SOURCE_FILE" file="%s" type="policy_template_metafile" />
         </structures>
       </release>
     </grit>''' % json_file_path
     grd_string_io = StringIO.StringIO(grd_text)
     # Parse the grit tree and load the policies' JSON with a gatherer.
     grd = grd_reader.Parse(grd_string_io, dir=tmp_dir_name)
+    grd.SetOutputContext('en', {})
     grd.RunGatherers(recursive=True)
     # Remove the policies' JSON.
     os.unlink(json_file_path)
     return grd
 
   def GetOutput(self, grd, env_lang, env_defs, out_type, out_lang):
     '''Generates an output of a writer.
 
     Args:
       grd: The root of the grit tree.
       env_lang: The environment language.
       env_defs: Environment definitions.
       out_type: Type of the output node for which output will be generated.
         This selects the writer.
       out_lang: Language of the output node for which output will be generated.
 
     Returns:
       The string of the tamplete created by the writer.
     '''
     grd.SetOutputContext(env_lang, env_defs)
     buf = StringIO.StringIO()
     build.RcBuilder.ProcessNode(grd, DummyOutput(out_type, out_lang), buf)
     return buf.getvalue()