Refactor source_control.py and add a test.

tools/auto_bisect/source_control_test.py

Index: tools/auto_bisect/source_control_test.py
diff --git a/tools/auto_bisect/source_control_test.py b/tools/auto_bisect/source_control_test.py
new file mode 100644
index 0000000000000000000000000000000000000000..ceba3e00f6804e5e52efe9e46c52fcae0cf7ccce
--- /dev/null
+++ b/tools/auto_bisect/source_control_test.py
@@ -0,0 +1,84 @@
+# Copyright 2014 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 source_control module."""
+
+import unittest
+import mock
+
+import source_control
+
+
+class SourceControlTest(unittest.TestCase):
+
+  @mock.patch('source_control.bisect_utils.CheckRunGit')
+  def testQueryRevisionInfo(self, mock_run_git):
+    # The QueryRevisionInfo function should run a sequence of git commands,
+    # then returns a dict with the results.
+    command_output_map = [
+        (['log', '--format=%aN', '-1', 'abcd1234'], 'Some Name\n'),
+        (['log', '--format=%aE', '-1', 'abcd1234'], 'somename@x.com'),
+        (['log', '--format=%s', '-1', 'abcd1234'], 'Commit subject '),
+        (['log', '--format=%cD', '-1', 'abcd1234'], 'Fri, 10 Oct 2014'),
+        (['log', '--format=%b', '-1', 'abcd1234'], 'Commit body\n'),
+    ]
+    _SetMockCheckRunGitBehavior(mock_run_git, command_output_map)
+    # The result of calling QueryRevisionInfo is a dictionary like that below.
+    # Trailing whitespace is stripped.
+    expected = {
+        'author': 'Some Name',
+        'email': 'somename@x.com',
+        'date': 'Fri, 10 Oct 2014',
+        'subject': 'Commit subject',
+        'body': 'Commit body',
+    }
+    self.assertEqual(expected, source_control.QueryRevisionInfo('abcd1234'))
+    self.assertEqual(5, mock_run_git.call_count)
+
+  def testResolveToRevision_InputGitHash(self):
+    # The ResolveToRevision function returns a git commit hash corresponding
+    # to the input, so if the input can't be parsed as an int, it is returned.
+    self.assertEqual(
+        'abcd1234',
+        source_control.ResolveToRevision('abcd1234', 'chromium', {}, 5))
+
+    # Note: It actually does this for any junk that isn't an int. This isn't
+    # necessarily desired behavior.
+    self.assertEqual(
+        'foo bar',
+        source_control.ResolveToRevision('foo bar', 'chromium', {}, 5))
+
+  @mock.patch('source_control.bisect_utils.CheckRunGit')
+  def testResolveToRevision_NotFound(self, mock_run_git):
+    # If no corresponding git hash was found, then None is returned.
+    mock_run_git.return_value = ''
+    self.assertIsNone(
+        source_control.ResolveToRevision('12345', 'chromium', {}, 5))
+
+  @mock.patch('source_control.bisect_utils.CheckRunGit')
+  def testResolveToRevision_Found(self, mock_run_git):
+    # In general, ResolveToRevision finds a git commit hash by repeatedly
+    # calling "git log --grep ..." with different numbers until something
+    # matches.
+    mock_run_git.return_value = 'abcd1234'
+    self.assertEqual(
+        'abcd1234',
+        source_control.ResolveToRevision('12345', 'chromium', {}, 5))
+    self.assertEqual(1, mock_run_git.call_count)
+
+
+def _SetMockCheckRunGitBehavior(mock_obj, command_output_map):
+  """Sets the behavior of a mock function according to the given mapping."""
+  # Unused argument 'cwd', expected in args list but not needed.
+  # pylint: disable=W0613
+  def FakeCheckRunGit(in_command, cwd=None):
+    for command, output in command_output_map:
+      if command == in_command:
+        return output
+  mock_obj.side_effect = FakeCheckRunGit
+
+
+if __name__ == '__main__':
+  unittest.main()
+