Refactor source_control.py and add a test.

tools/auto_bisect/bisect_results.py

 # 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.
 
 import math
 import os
 
 import bisect_utils
 import math_utils
+import source_control
 import ttest
 
 
 def ConfidenceScore(good_results_lists, bad_results_lists):
   """Calculates a confidence score.
 
   This score is a percentage which represents our degree of confidence in the
   proposition that the good results and bad results are distinct groups, and
   their differences aren't due to chance alone.
 
@@ skipping 21 matching lines @@
     return 0.0
 
   # The p-value is approximately the probability of obtaining the given set
   # of good and bad values just by chance.
   _, _, p_value = ttest.WelchsTTest(sample1, sample2)
   return 100.0 * (1.0 - p_value)
 
 
 class BisectResults(object):
 
-  def __init__(self, depot_registry, source_control):
+  def __init__(self, depot_registry):
     self._depot_registry = depot_registry
     self.revision_data = {}
     self.error = None
-    self._source_control = source_control
 
   @staticmethod
   def _FindOtherRegressions(revision_data_sorted, bad_greater_than_good):
     """Compiles a list of other possible regressions from the revision data.
 
     Args:
       revision_data_sorted: Sorted list of (revision, revision data) pairs.
       bad_greater_than_good: Whether the result value at the "bad" revision is
           numerically greater than the result value at the "good" revision.
 
@@ skipping 159 matching lines @@
             # <SHA1>
             # etc.
             if l[0] == '/':
               last_depot = l
             else:
               contents = l.split(' ')
               if len(contents) > 1:
                 changes.append([last_depot, contents[0]])
         for c in changes:
           os.chdir(c[0])
-          info = self._source_control.QueryRevisionInfo(c[1])
+          info = source_control.QueryRevisionInfo(c[1])
           culprit_revisions.append((c[1], info, None))
       else:
         for i in xrange(last_broken_revision_index, len(revision_data_sorted)):
           k, v = revision_data_sorted[i]
           if k == first_working_revision:
             break
           self._depot_registry.ChangeToDepotDir(v['depot'])
-          info = self._source_control.QueryRevisionInfo(k)
+          info = source_control.QueryRevisionInfo(k)
           culprit_revisions.append((k, info, v['depot']))
       os.chdir(cwd)
 
       # Check for any other possible regression ranges.
       other_regressions = self._FindOtherRegressions(
           revision_data_sorted, mean_of_bad_runs > mean_of_good_runs)
 
     return {
         'first_working_revision': first_working_revision,
         'last_broken_revision': last_broken_revision,
         'culprit_revisions': culprit_revisions,
         'other_regressions': other_regressions,
         'regression_size': regression_size,
         'regression_std_err': regression_std_err,
         'confidence': confidence,
         'revision_data_sorted': revision_data_sorted
     }