git cl test framework: improve debuggability of expected calls.

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 195 matching lines @@
     # Gerrrit.
     test('https://chrome-review.source.com/c/123/4',
          123, 4, 'chrome-review.source.com')
     test('https://chrome-review.source.com/bad/123/4', fail=True)
 
 
 class TestGitCl(TestCase):
   def setUp(self):
     super(TestGitCl, self).setUp()
     self.calls = []
-    self._calls_done = 0
+    self._calls_done = []
     self.mock(subprocess2, 'call', self._mocked_call)
     self.mock(subprocess2, 'check_call', self._mocked_call)
     self.mock(subprocess2, 'check_output', self._mocked_call)
     self.mock(subprocess2, 'communicate', self._mocked_call)
     self.mock(git_cl.gclient_utils, 'CheckCallAndFilter', self._mocked_call)
     self.mock(git_common, 'is_dirty_git_tree', lambda x: False)
     self.mock(git_common, 'get_or_create_merge_base',
               lambda *a: (
                   self._mocked_call(['get_or_create_merge_base']+list(a))))
     self.mock(git_cl, 'BranchExists', lambda _: True)
@@ skipping 17 matching lines @@
       # included, has failed. That means current test may have actually ran
       # fine, and the check for no leftover calls would be skipped.
       if not self.has_failed():
         self.assertEquals([], self.calls)
     finally:
       super(TestGitCl, self).tearDown()
 
   def _mocked_call(self, *args, **_kwargs):
     self.assertTrue(
         self.calls,
-        '@%d  Expected: <Missing>   Actual: %r' % (self._calls_done, args))
+        '@%d  Expected: <Missing>   Actual: %r' % (len(self._calls_done), args))
     top = self.calls.pop(0)
     if len(top) > 2 and top[2]:
       raise top[2]
     expected_args, result = top
 
     # Also logs otherwise it could get caught in a try/finally and be hard to
     # diagnose.
     if expected_args != args:
-      msg = '@%d  Expected: %r   Actual: %r' % (
-          self._calls_done, expected_args, args)
-      git_cl.logging.error(msg)
-      self.fail(msg)
-    self._calls_done += 1
+      N = 5
+      prior_calls  = '\n  '.join(
+          '@%d: %r' % (len(self._calls_done) - N + i, c[0])
+          for i, c in enumerate(self._calls_done[-N:]))
+      following_calls = '\n  '.join(
+          '@%d: %r' % (len(self._calls_done) + i + 1, c[0])
+          for i, c in enumerate(self.calls[:N]))
+      extended_msg = (
+          'A few prior calls:\n  %s\n\n'
+          'This (expected):\n  @%d: %r\n'
+          'This (actual):\n  @%d: %r\n\n'
+          'A few following expected calls:\n  %s' %
+          (prior_calls, len(self._calls_done), expected_args,
+           len(self._calls_done), args, following_calls))
+      git_cl.logging.error(extended_msg)
+
+      self.fail('@%d  Expected: %r   Actual: %r' % (
+          len(self._calls_done), expected_args, args))
+
+    self._calls_done.append(top)
     return result
 
   @classmethod
   def _is_gerrit_calls(cls, gerrit=False):
     return [((['git', 'config', 'rietveld.autoupdate'],), ''),
             ((['git', 'config', 'gerrit.host'],), 'True' if gerrit else '')]
 
   @classmethod
   def _upload_calls(cls, similarity, find_copies, private):
     return (cls._git_base_calls(similarity, find_copies) +
@@ skipping 1350 matching lines @@
         ((['rm_file_or_tree', '/abs/git_repo_root/.git/hooks/commit-msg'],),
          ''),
     ]
     cl._codereview_impl._GerritCommitMsgHookCheck(offer_removal=True)
 
 
 if __name__ == '__main__':
   git_cl.logging.basicConfig(
       level=git_cl.logging.DEBUG if '-v' in sys.argv else git_cl.logging.ERROR)
   unittest.main()