61   def commit_exists(self, commit):  argument
62     """Checks to see if a commit exists in the project repo.
65       commit: The commit SHA you are checking.
68       True if the commit exits in the project.
70     if not commit.rstrip():
73     _, _, err_code = self.git(['cat-file', '-e', commit])
76   def commit_date(self, commit):  argument
77     """Get the date of a commit.
80       commit: The commit hash.
83       A datetime representing the date of the commit.
85     out, _, _ = self.git(['show', '-s', '--format=%ct', commit],
108     """Gets the current commit SHA of the repo.
111       The current active commit SHA.
116   def get_parent(self, commit, count):  argument
117     """Gets the count'th parent of the given commit.
120       The parent commit SHA.
123     out, _, err_code = self.git(['rev-parse', commit + '~' + str(count)],
142       newest_commit: The newest commit to be in the list.
143       oldest_commit: The (optional) oldest commit to be in the list.
146       The list of commit SHAs from newest to oldest.
149       ValueError: When either the oldest or newest commit does not exist.
150       RuntimeError: When there is an error getting the commit list.
154       raise ValueError('The oldest commit %s does not exist' % oldest_commit)
156       raise ValueError('The newest commit %s does not exist' % newest_commit)
171     commits = [commit for commit in commits if commit]
173       raise RuntimeError('Error getting commit list between %s and %s ' %
204   def checkout_commit(self, commit, clean=True):  argument
205     """Checks out a specific commit from the repo.
208       commit: The commit SHA to be checked out.
212       ValueError: when commit does not exist.
215     if not self.commit_exists(commit):
216       raise ValueError('Commit %s does not exist in current branch' % commit)
217     self.git(['checkout', '-f', commit], check_result=True)
220     if self.get_current_commit() != commit:
221       raise RuntimeError('Error checking out commit %s' % commit)