Test for r183. gcl didn't land it, for some reason.

grit/tool/build_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.
 
 '''Unit tests for the 'grit build' tool.
 '''
 
 import codecs
 import os
@@ skipping 227 matching lines @@
         'IDR_STRUCTURE_IN_FALSE_IF_NOT_WHITELISTED',
         'IDR_INCLUDE_NOT_WHITELISTED',
     ]
     for output_file in (header, map_cc):
       self._verifyWhitelistedOutput(
         output_file,
         whitelisted_ids,
         non_whitelisted_ids,
       )
 
+  def testWriteOnlyNew(self):
+    output_dir = tempfile.mkdtemp()
+    builder = build.RcBuilder()
+    class DummyOpts(object):
+      def __init__(self):
+        self.input = util.PathFromRoot('grit/testdata/substitute.grd')
+        self.verbose = False
+        self.extra_verbose = False
+    UNCHANGED = 10
+    header = os.path.join(output_dir, 'resource.h')
+
+    builder.Run(DummyOpts(), ['-o', output_dir])
+    self.failUnless(os.path.exists(header))
+    first_mtime = os.stat(header).st_mtime
+
+    os.utime(header, (UNCHANGED, UNCHANGED))
+    builder.Run(DummyOpts(), ['-o', output_dir, '--write-only-new', '0'])
+    self.failUnless(os.path.exists(header))
+    second_mtime = os.stat(header).st_mtime
+
+    os.utime(header, (UNCHANGED, UNCHANGED))
+    builder.Run(DummyOpts(), ['-o', output_dir, '--write-only-new', '1'])
+    self.failUnless(os.path.exists(header))
+    third_mtime = os.stat(header).st_mtime
+
+    self.assertTrue(abs(second_mtime - UNCHANGED) > 5)
+    self.assertTrue(abs(third_mtime - UNCHANGED) < 5)
+
 
 if __name__ == '__main__':
   unittest.main()