git cl: add python implementation of Change-Id generation.

tests/git_cl_test.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 git_cl.py."""
 
 import os
 import StringIO
 import stat
@@ skipping 728 matching lines @@
       def GetIssue(self):
         return '123'
       def GetPatchset(self):
         return '1001'
 
     ret = git_cl.upload_branch_deps(MockChangelist(), [])
     # CMDupload should have been called 5 times because of 5 dependent branches.
     self.assertEquals(5, record_calls.times_called)
     self.assertEquals(0, ret)
 
+  def test_gerrit_change_id(self):
+    self.calls = [
+        ((['git', 'write-tree'], ),
+          'hashtree'),
+        ((['git', 'rev-parse', 'HEAD~0'], ),
+          'branch-parent'),
+        ((['git', 'var', 'GIT_AUTHOR_IDENT'], ),
+          'A B <a@b.org> 1456848326 +0100'),
+        ((['git', 'var', 'GIT_COMMITTER_IDENT'], ),
+          'C D <c@d.org> 1456858326 +0100'),
+        ((['git', 'hash-object', '-t', 'commit', '--stdin'], ),
+          'hashchange'),
+    ]
+    change_id = git_cl.GenerateGerritChangeId('line1\nline2\n')
+    self.assertEqual(change_id, 'Ihashchange')
+
   def test_config_gerrit_download_hook(self):
     self.mock(git_cl, 'FindCodereviewSettingsFile', CodereviewSettingsFileMock)
     def ParseCodereviewSettingsContent(content):
       keyvals = {}
       keyvals['CODE_REVIEW_SERVER'] = 'gerrit.chromium.org'
       keyvals['GERRIT_HOST'] = 'True'
       return keyvals
     self.mock(git_cl.gclient_utils, 'ParseCodereviewSettingsContent',
               ParseCodereviewSettingsContent)
     self.mock(git_cl.os, 'access', self._mocked_call)
@@ skipping 195 matching lines @@
     self.calls += [
       ((['git', 'apply', '--index', '-p0', '--3way'],), '',
        subprocess2.CalledProcessError(1, '', '', '', '')),
     ]
     self.assertNotEqual(git_cl.main(['patch', '123456']), 0)
 
 if __name__ == '__main__':
   git_cl.logging.basicConfig(
       level=git_cl.logging.DEBUG if '-v' in sys.argv else git_cl.logging.ERROR)
   unittest.main()