Revert of Refactor source_control.py and add a test.

tools/auto_bisect/source_control.py

Index: tools/auto_bisect/source_control.py
diff --git a/tools/auto_bisect/source_control.py b/tools/auto_bisect/source_control.py
index d3a086bdd0fc5946e341fe28b51328a2a081b9f5..10b978074c225685e0686cae354f86d646b4461a 100644
--- a/tools/auto_bisect/source_control.py
+++ b/tools/auto_bisect/source_control.py
@@ -2,7 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-"""This module contains functions for performing source control operations."""
+"""This module contains the SourceControl class and related functions."""
 
 import os
 
@@ -11,253 +11,284 @@
 CROS_VERSION_PATTERN = 'new version number from %s'
 
 
-def IsInGitRepository():
-  output, _ = bisect_utils.RunGit(['rev-parse', '--is-inside-work-tree'])
-  return output.strip() == 'true'
-
-
-def SyncToRevisionWithGClient(revision):
-  """Uses gclient to sync to the specified revision.
-
-  This is like running gclient sync --revision <revision>.
-
-  Args:
-    revision: A git SHA1 hash or SVN revision number (depending on workflow).
+def DetermineAndCreateSourceControl(opts):
+  """Attempts to determine the underlying source control workflow and returns
+  a SourceControl object.
 
   Returns:
-    The return code of the call.
+    An instance of a SourceControl object, or None if the current workflow
+    is unsupported.
   """
-  return bisect_utils.RunGClient(
-      ['sync', '--verbose', '--reset', '--force',
-      '--delete_unversioned_trees', '--nohooks', '--revision', revision])
-
-
-def SyncToRevisionWithRepo(timestamp):
-  return bisect_utils.RunRepoSyncAtTimestamp(timestamp)
-
-
-def GetRevisionList(end_revision_hash, start_revision_hash, cwd=None):
-  """Retrieves a list of git commit hashes in a range.
-
-  Args:
-    end_revision_hash: The SHA1 for the end of the range, inclusive.
-    start_revision_hash: The SHA1 for the beginning of the range, inclusive.
-
-  Returns:
-    A list of the git commit hashes in the range, in reverse time order --
-    that is, starting with |end_revision_hash|.
-  """
-  revision_range = '%s..%s' % (start_revision_hash, end_revision_hash)
-  cmd = ['log', '--format=%H', '-10000', '--first-parent', revision_range]
-  log_output = bisect_utils.CheckRunGit(cmd, cwd=cwd)
-
-  revision_hash_list = log_output.split()
-  revision_hash_list.append(start_revision_hash)
-
-  return revision_hash_list
-
-
-def SyncToRevision(revision, sync_client=None):
-  if not sync_client:
-    _, return_code = bisect_utils.RunGit(['checkout', revision])[1]
-  elif sync_client == 'gclient':
-    return_code = SyncToRevisionWithGClient(revision)
-  elif sync_client == 'repo':
-    return_code = SyncToRevisionWithRepo(revision)
-  else:
-    raise NotImplementedError('Unsupported sync_client: "%s"' % sync_client)
-
-  return not return_code
-
-
-def ResolveToRevision(revision_to_check, depot, depot_deps_dict,
-                      search, cwd=None):
-  """Tries to resolve an SVN revision or commit position to a git SHA1.
-
-  Args:
-    revision_to_check: The user supplied revision string that may need to be
-        resolved to a git commit hash. This may be an SVN revision, git commit
-        position, or a git commit hash.
-    depot: The depot (dependency repository) that |revision_to_check| is from.
-    depot_deps_dict: A dictionary with information about different depots.
-    search: How many revisions forward or backward to search. If the value is
-        negative, the function will search backwards chronologically, otherwise
-        it will search forward.
-
-  Returns:
-    A string containing a git SHA1 hash, otherwise None.
-  """
-  # Android-chrome is git only, so no need to resolve this to anything else.
-  if depot == 'android-chrome':
-    return revision_to_check
-
-  if depot == 'cros':
-    return ResolveToRevisionCrOS(revision_to_check, cwd)
-
-  # If the given revision can't be parsed as an integer, then it may already
-  # be a git commit hash.
-  if not bisect_utils.IsStringInt(revision_to_check):
-    return revision_to_check
-
-  depot_svn = 'svn://svn.chromium.org/chrome/trunk/src'
-
-  if depot != 'chromium':
-    depot_svn = depot_deps_dict[depot]['svn']
-  svn_revision = int(revision_to_check)
-  git_revision = None
-
-  if search > 0:
-    search_range = xrange(svn_revision, svn_revision + search, 1)
-  else:
-    search_range = xrange(svn_revision, svn_revision + search, -1)
-
-  for i in search_range:
-    # NOTE: Checking for the git-svn-id footer is for backwards compatibility.
-    # When we can assume that all the revisions we care about are from after
-    # git commit positions started getting added, we don't need to check this.
-    svn_pattern = 'git-svn-id: %s@%d' % (depot_svn, i)
-    commit_position_pattern = '^Cr-Commit-Position: .*@{#%d}' % i
-    cmd = ['log', '--format=%H', '-1', '--grep', svn_pattern,
-           '--grep', commit_position_pattern, 'origin/master']
+  (output, _) = bisect_utils.RunGit(['rev-parse', '--is-inside-work-tree'])
+
+  if output.strip() == 'true':
+    return GitSourceControl(opts)
+
+  return None
+
+
+# TODO(qyearsley): Almost all of the methods below could be top-level functions
+# (or class methods). Refactoring may make this simpler.
+# pylint: disable=R0201
+class SourceControl(object):
+  """SourceControl is an abstraction over the source control system."""
+
+  def __init__(self):
+    super(SourceControl, self).__init__()
+
+  def SyncToRevisionWithGClient(self, revision):
+    """Uses gclient to sync to the specified revision.
+
+    This is like running gclient sync --revision <revision>.
+
+    Args:
+      revision: A git SHA1 hash or SVN revision number (depending on workflow).
+
+    Returns:
+      The return code of the call.
+    """
+    return bisect_utils.RunGClient(['sync', '--verbose', '--reset', '--force',
+        '--delete_unversioned_trees', '--nohooks', '--revision', revision])
+
+  def SyncToRevisionWithRepo(self, timestamp):
+    """Uses the repo command to sync all the underlying git depots to the
+    specified time.
+
+    Args:
+      timestamp: The Unix timestamp to sync to.
+
+    Returns:
+      The return code of the call.
+    """
+    return bisect_utils.RunRepoSyncAtTimestamp(timestamp)
+
+
+class GitSourceControl(SourceControl):
+  """GitSourceControl is used to query the underlying source control."""
+
+  def __init__(self, opts):
+    super(GitSourceControl, self).__init__()
+    self.opts = opts
+
+  def IsGit(self):
+    return True
+
+  def GetRevisionList(self, revision_range_end, revision_range_start, cwd=None):
+    """Retrieves a list of revisions between |revision_range_start| and
+    |revision_range_end|.
+
+    Args:
+      revision_range_end: The SHA1 for the end of the range.
+      revision_range_start: The SHA1 for the beginning of the range.
+
+    Returns:
+      A list of the revisions between |revision_range_start| and
+      |revision_range_end| (inclusive).
+    """
+    revision_range = '%s..%s' % (revision_range_start, revision_range_end)
+    cmd = ['log', '--format=%H', '-10000', '--first-parent', revision_range]
     log_output = bisect_utils.CheckRunGit(cmd, cwd=cwd)
+
+    revision_hash_list = log_output.split()
+    revision_hash_list.append(revision_range_start)
+
+    return revision_hash_list
+
+  def SyncToRevision(self, revision, sync_client=None):
+    """Syncs to the specified revision.
+
+    Args:
+      revision: The revision to sync to.
+      use_gclient: Specifies whether or not we should sync using gclient or
+        just use source control directly.
+
+    Returns:
+      True if successful.
+    """
+
+    if not sync_client:
+      results = bisect_utils.RunGit(['checkout', revision])[1]
+    elif sync_client == 'gclient':
+      results = self.SyncToRevisionWithGClient(revision)
+    elif sync_client == 'repo':
+      results = self.SyncToRevisionWithRepo(revision)
+
+    return not results
+
+  def ResolveToRevision(self, revision_to_check, depot, depot_deps_dict,
+                        search, cwd=None):
+    """Tries to resolve an SVN revision or commit position to a git SHA1.
+
+    Args:
+      revision_to_check: The user supplied revision string that may need to be
+        resolved to a git SHA1.
+      depot: The depot the revision_to_check is from.
+      depot_deps_dict: A dictionary with information about different depots.
+      search: The number of changelists to try if the first fails to resolve
+        to a git hash. If the value is negative, the function will search
+        backwards chronologically, otherwise it will search forward.
+
+    Returns:
+      A string containing a git SHA1 hash, otherwise None.
+    """
+    # Android-chrome is git only, so no need to resolve this to anything else.
+    if depot == 'android-chrome':
+      return revision_to_check
+
+    if depot != 'cros':
+      if not bisect_utils.IsStringInt(revision_to_check):
+        return revision_to_check
+
+      depot_svn = 'svn://svn.chromium.org/chrome/trunk/src'
+
+      if depot != 'chromium':
+        depot_svn = depot_deps_dict[depot]['svn']
+
+      svn_revision = int(revision_to_check)
+      git_revision = None
+
+      if search > 0:
+        search_range = xrange(svn_revision, svn_revision + search, 1)
+      else:
+        search_range = xrange(svn_revision, svn_revision + search, -1)
+
+      for i in search_range:
+        svn_pattern = 'git-svn-id: %s@%d' % (depot_svn, i)
+        commit_position_pattern = '^Cr-Commit-Position: .*@{#%d}' % i
+        cmd = ['log', '--format=%H', '-1', '--grep', svn_pattern,
+               '--grep', commit_position_pattern, 'origin/master']
+
+        (log_output, return_code) = bisect_utils.RunGit(cmd, cwd=cwd)
+
+        assert not return_code, 'An error occurred while running'\
+                                ' "git %s"' % ' '.join(cmd)
+
+        if not return_code:
+          log_output = log_output.strip()
+
+          if log_output:
+            git_revision = log_output
+
+            break
+
+      return git_revision
+    else:
+      if bisect_utils.IsStringInt(revision_to_check):
+        return int(revision_to_check)
+      else:
+        cwd = os.getcwd()
+        os.chdir(os.path.join(os.getcwd(), 'src', 'third_party',
+            'chromiumos-overlay'))
+        pattern = CROS_VERSION_PATTERN % revision_to_check
+        cmd = ['log', '--format=%ct', '-1', '--grep', pattern]
+
+        git_revision = None
+
+        log_output = bisect_utils.CheckRunGit(cmd, cwd=cwd)
+        if log_output:
+          git_revision = log_output
+          git_revision = int(log_output.strip())
+        os.chdir(cwd)
+
+        return git_revision
+
+  def IsInProperBranch(self):
+    """Confirms they're in the master branch for performing the bisection.
+    This is needed or gclient will fail to sync properly.
+
+    Returns:
+      True if the current branch on src is 'master'
+    """
+    cmd = ['rev-parse', '--abbrev-ref', 'HEAD']
+    log_output = bisect_utils.CheckRunGit(cmd)
     log_output = log_output.strip()
 
-    if log_output:
-      git_revision = log_output
-      break
-
-  return git_revision
-
-
-def ResolveToRevisionCrOS(revision_to_check, cwd=None):
-  """Return a git commit hash corresponding to the give version or revision.
-
-  TODO(qyearsley): Either verify that this works or delete it.
-  """
-  if bisect_utils.IsStringInt(revision_to_check):
-    return int(revision_to_check)
-
-  cwd = os.getcwd()
-  os.chdir(os.path.join(os.getcwd(), 'src', 'third_party',
-                        'chromiumos-overlay'))
-  pattern = CROS_VERSION_PATTERN % revision_to_check
-  cmd = ['log', '--format=%ct', '-1', '--grep', pattern]
-
-  git_revision = None
-
-  log_output = bisect_utils.CheckRunGit(cmd, cwd=cwd)
-  if log_output:
-    git_revision = log_output
-    git_revision = int(log_output.strip())
-  os.chdir(cwd)
-
-  return git_revision
-
-
-def IsInProperBranch():
-  """Checks whether the current branch is "master"."""
-  cmd = ['rev-parse', '--abbrev-ref', 'HEAD']
-  log_output = bisect_utils.CheckRunGit(cmd)
-  log_output = log_output.strip()
-  return log_output == 'master'
-
-
-def GetCommitPosition(git_revision, cwd=None):
-  """Finds git commit postion for the given git hash.
-
-  This function executes "git footer --position-num <git hash>" command to get
-  commit position the given revision.
-
-  Args:
-    git_revision: The git SHA1 to use.
-    cwd: Working directory to run the command from.
-
-  Returns:
-    Git commit position as integer or None.
-  """
-  cmd = ['footers', '--position-num', git_revision]
-  output = bisect_utils.CheckRunGit(cmd, cwd)
-  commit_position = output.strip()
-
-  if bisect_utils.IsStringInt(commit_position):
-    return int(commit_position)
-
-  return None
-
-
-def QueryRevisionInfo(revision, cwd=None):
-  """Gathers information on a particular revision, such as author's name,
-  email, subject, and date.
-
-  Args:
-    revision: Revision you want to gather information on; a git commit hash.
-
-  Returns:
-    A dict in the following format:
-    {
-      'author': %s,
-      'email': %s,
-      'date': %s,
-      'subject': %s,
-      'body': %s,
-    }
-  """
-  commit_info = {}
-
-  formats = ['%aN', '%aE', '%s', '%cD', '%b']
-  targets = ['author', 'email', 'subject', 'date', 'body']
-
-  for i in xrange(len(formats)):
-    cmd = ['log', '--format=%s' % formats[i], '-1', revision]
-    output = bisect_utils.CheckRunGit(cmd, cwd=cwd)
-    commit_info[targets[i]] = output.rstrip()
-
-  return commit_info
-
-
-def CheckoutFileAtRevision(file_name, revision, cwd=None):
-  """Performs a checkout on a file at the given revision.
-
-  Returns:
-    True if successful.
-  """
-  command = ['checkout', revision, file_name]
-  _, return_code = bisect_utils.RunGit(command, cwd=cwd)
-  return not return_code
-
-
-def RevertFileToHead(file_name):
-  """Un-stages a file and resets the file's state to HEAD.
-
-  Returns:
-    True if successful.
-  """
-  # Reset doesn't seem to return 0 on success.
-  bisect_utils.RunGit(['reset', 'HEAD', file_name])
-  _, return_code = bisect_utils.RunGit(
-      ['checkout', bisect_utils.FILE_DEPS_GIT])
-  return not return_code
-
-
-def QueryFileRevisionHistory(filename, revision_start, revision_end):
-  """Returns a list of commits that modified this file.
-
-  Args:
-    filename: Name of file.
-    revision_start: Start of revision range (inclusive).
-    revision_end: End of revision range.
-
-  Returns:
-    Returns a list of commits that touched this file.
-  """
-  cmd = [
-      'log',
-      '--format=%H',
-      '%s~1..%s' % (revision_start, revision_end),
-      '--',
-      filename,
-  ]
-  output = bisect_utils.CheckRunGit(cmd)
-  lines = output.split('\n')
-  return [o for o in lines if o]
-
+    return log_output == "master"
+
+  def GetCommitPosition(self, git_revision, cwd=None):
+    """Finds git commit postion for the given git hash.
+
+    This function executes "git footer --position-num <git hash>" command to get
+    commit position the given revision.
+
+    Args:
+      git_revision: The git SHA1 to use.
+      cwd: Working directory to run the command from.
+
+    Returns:
+      Git commit position as integer or None.
+    """
+    cmd = ['footers', '--position-num', git_revision]
+    output = bisect_utils.CheckRunGit(cmd, cwd)
+    commit_position = output.strip()
+
+    if bisect_utils.IsStringInt(commit_position):
+      return int(commit_position)
+
+    return None
+
+  def QueryRevisionInfo(self, revision, cwd=None):
+    """Gathers information on a particular revision, such as author's name,
+    email, subject, and date.
+
+    Args:
+      revision: Revision you want to gather information on.
+
+    Returns:
+      A dict in the following format:
+      {
+        'author': %s,
+        'email': %s,
+        'date': %s,
+        'subject': %s,
+        'body': %s,
+      }
+    """
+    commit_info = {}
+
+    formats = ['%aN', '%aE', '%s', '%cD', '%b']
+    targets = ['author', 'email', 'subject', 'date', 'body']
+
+    for i in xrange(len(formats)):
+      cmd = ['log', '--format=%s' % formats[i], '-1', revision]
+      output = bisect_utils.CheckRunGit(cmd, cwd=cwd)
+      commit_info[targets[i]] = output.rstrip()
+
+    return commit_info
+
+  def CheckoutFileAtRevision(self, file_name, revision, cwd=None):
+    """Performs a checkout on a file at the given revision.
+
+    Returns:
+      True if successful.
+    """
+    return not bisect_utils.RunGit(
+        ['checkout', revision, file_name], cwd=cwd)[1]
+
+  def RevertFileToHead(self, file_name):
+    """Un-stages a file and resets the file's state to HEAD.
+
+    Returns:
+      True if successful.
+    """
+    # Reset doesn't seem to return 0 on success.
+    bisect_utils.RunGit(['reset', 'HEAD', file_name])
+
+    return not bisect_utils.RunGit(['checkout', bisect_utils.FILE_DEPS_GIT])[1]
+
+  def QueryFileRevisionHistory(self, filename, revision_start, revision_end):
+    """Returns a list of commits that modified this file.
+
+    Args:
+        filename: Name of file.
+        revision_start: Start of revision range.
+        revision_end: End of revision range.
+
+    Returns:
+        Returns a list of commits that touched this file.
+    """
+    cmd = ['log', '--format=%H', '%s~1..%s' % (revision_start, revision_end),
+           '--', filename]
+    output = bisect_utils.CheckRunGit(cmd)
+
+    return [o for o in output.split('\n') if o]