How to use the perceval.backends.core.git.Git function in perceval

def test_fetch_branch(self):
        """Test whether commits are fetched from a Git repository for a given branch"""

        new_path = os.path.join(self.tmp_path, 'newgit')

        from_date = datetime.datetime(2014, 2, 11, 22, 7, 49)
        git = Git(self.git_path, new_path)
        # Let's fetch master
        commits = [commit for commit in git.fetch(branches=['master'])]

        expected = ['bc57a9209f096a130dcc5ba7089a8663f758a703',
                    '87783129c3f00d2c81a3a8e585eb86a47e39891a',
                    '7debcf8a2f57f86663809c58b5c07a398be7674c',
                    'c0d66f92a95e31c77be08dc9d0f11a16715d1885',
                    'c6ba8f7a1058db3e6b4bc6f1090e932b107605fb',
                    '589bb080f059834829a2a5955bebfd7c2baa110a',
                    'ce8e0b86a1e9877f42fe9453ede418519115f367',
                    '51a3b654f252210572297f47597b31527c475fb8',
                    '456a68ee1407a77f3e804a30dff245bb6c6b872f']

        self.assertEqual(len(commits), len(expected))

        for x in range(len(commits)):

def test_fetch_latest_items(self):
        """Test whether latest commits are fetched from a Git repository"""

        origin_path = os.path.join(self.tmp_repo_path, 'gittest')
        editable_path = os.path.join(self.tmp_path, 'editgit')
        new_path = os.path.join(self.tmp_path, 'newgit')
        new_file = os.path.join(editable_path, 'newfile')

        shutil.copytree(origin_path, editable_path)

        git = Git(editable_path, new_path)
        commits = [commit for commit in git.fetch(latest_items=True)]

        # Count the number of commits before adding some new
        expected = [('bc57a9209f096a130dcc5ba7089a8663f758a703', 1344965413.0),
                    ('87783129c3f00d2c81a3a8e585eb86a47e39891a', 1344965535.0),
                    ('7debcf8a2f57f86663809c58b5c07a398be7674c', 1344965607.0),
                    ('c0d66f92a95e31c77be08dc9d0f11a16715d1885', 1344965702.0),
                    ('c6ba8f7a1058db3e6b4bc6f1090e932b107605fb', 1344966351.0),
                    ('589bb080f059834829a2a5955bebfd7c2baa110a', 1344967441.0),
                    ('ce8e0b86a1e9877f42fe9453ede418519115f367', 1392185269.0),
                    ('51a3b654f252210572297f47597b31527c475fb8', 1392185366.0),
                    ('456a68ee1407a77f3e804a30dff245bb6c6b872f', 1392185439.0)]

        self.assertEqual(len(commits), len(expected))

        for x in range(len(commits)):

for x in range(len(commits)):
            expected_uuid = uuid(self.git_path, expected[x][0])
            commit = commits[x]
            self.assertEqual(commit['data']['commit'], expected[x][0])
            self.assertEqual(commit['origin'], self.git_path)
            self.assertEqual(commit['uuid'], expected_uuid)
            self.assertEqual(commit['updated_on'], expected[x][1])
            self.assertEqual(commit['category'], 'commit')
            self.assertEqual(commit['tag'], self.git_path)

        # Test it using a datetime that includes the timezone
        from_date = datetime.datetime(2012, 8, 14, 7, 34, 00,
                                      tzinfo=dateutil.tz.tzoffset(None, -36000))
        to_date = datetime.datetime(2012, 8, 14, 14, 30, 00,
                                    tzinfo=dateutil.tz.tzoffset(None, -36000))
        git = Git(self.git_path, new_path)
        commits = [commit for commit in git.fetch(from_date=from_date, to_date=to_date)]

        self.assertEqual(len(commits), len(expected))

        for x in range(len(commits)):
            expected_uuid = uuid(self.git_path, expected[x][0])
            commit = commits[x]
            self.assertEqual(commit['data']['commit'], expected[x][0])
            self.assertEqual(commit['origin'], self.git_path)
            self.assertEqual(commit['uuid'], expected_uuid)
            self.assertEqual(commit['updated_on'], expected[x][1])
            self.assertEqual(commit['category'], 'commit')
            self.assertEqual(commit['tag'], self.git_path)

        shutil.rmtree(new_path)

def test_initialization(self):
        """Test whether attributes are initializated"""

        git = Git('http://example.com', self.git_path, tag='test')

        self.assertEqual(git.uri, 'http://example.com')
        self.assertEqual(git.gitpath, self.git_path)
        self.assertEqual(git.origin, 'http://example.com')
        self.assertEqual(git.tag, 'test')

        # When tag is empty or None it will be set to
        # the value in uri
        git = Git('http://example.com', self.git_path)
        self.assertEqual(git.origin, 'http://example.com')
        self.assertEqual(git.tag, 'http://example.com')

        git = Git('http://example.com', self.git_path, tag='')
        self.assertEqual(git.origin, 'http://example.com')
        self.assertEqual(git.tag, 'http://example.com')

def test_fetch_empty_log(self):
        """Test whether it parsers an empty log"""

        new_path = os.path.join(self.tmp_path, 'newgit')

        from_date = datetime.datetime(2020, 1, 1, 1, 1, 1)
        git = Git(self.git_path, new_path)
        commits = [commit for commit in git.fetch(from_date=from_date)]

        self.assertListEqual(commits, [])

        to_date = datetime.datetime(1970, 1, 1, 1, 1, 1)
        git = Git(self.git_path, new_path)
        commits = [commit for commit in git.fetch(to_date=to_date)]

        self.assertListEqual(commits, [])

        shutil.rmtree(new_path)

"""Test whether attributes are initializated"""

        git = Git('http://example.com', self.git_path, tag='test')

        self.assertEqual(git.uri, 'http://example.com')
        self.assertEqual(git.gitpath, self.git_path)
        self.assertEqual(git.origin, 'http://example.com')
        self.assertEqual(git.tag, 'test')

        # When tag is empty or None it will be set to
        # the value in uri
        git = Git('http://example.com', self.git_path)
        self.assertEqual(git.origin, 'http://example.com')
        self.assertEqual(git.tag, 'http://example.com')

        git = Git('http://example.com', self.git_path, tag='')
        self.assertEqual(git.origin, 'http://example.com')
        self.assertEqual(git.tag, 'http://example.com')

def test_fetch_from_file(self):
        """Test whether commits are fetched from a Git log file"""

        git = Git('http://example.com.git', os.path.join(os.path.dirname(os.path.abspath(__file__)), 'data/git/git_log.txt'))
        commits = [commit for commit in git.fetch()]

        expected = [('456a68ee1407a77f3e804a30dff245bb6c6b872f', 1392185439.0),
                    ('51a3b654f252210572297f47597b31527c475fb8', 1392185366.0),
                    ('ce8e0b86a1e9877f42fe9453ede418519115f367', 1392185269.0),
                    ('589bb080f059834829a2a5955bebfd7c2baa110a', 1344967441.0),
                    ('c6ba8f7a1058db3e6b4bc6f1090e932b107605fb', 1344966351.0),
                    ('c0d66f92a95e31c77be08dc9d0f11a16715d1885', 1344965702.0),
                    ('7debcf8a2f57f86663809c58b5c07a398be7674c', 1344965607.0),
                    ('87783129c3f00d2c81a3a8e585eb86a47e39891a', 1344965535.0),
                    ('bc57a9209f096a130dcc5ba7089a8663f758a703', 1344965413.0),
                    ('49345fe87bd1dfad7e682f6554f7472c5576a8c7', 1515508249.0)]

        self.assertEqual(len(commits), len(expected))

        for x in range(len(commits)):

def _init_repository(self):
        logger.info("Initializing importer for repository [%s]",
                    self.object.url)
        self.repo_path = self._get_checkout_path()

        self.backend = git.Git(self.object.url, self.repo_path)

from ._version import __version__

CATEGORY_GRAAL = 'graal'
DEFAULT_WORKTREE_PATH = '/tmp/worktrees/'
GIT_EXEC_PATH = '/usr/bin/git'

logger = logging.getLogger(__name__)


class GraalError(BaseError):
    """Generic error for graal backends"""

    message = "%(cause)s"


class Graal(Git):
    """Generic Repository AnALyzer backend.

    This class inherits from Git backend, thus it fetches the commits
    from a local Git repository and enables to add the result of
    the analysis within the `analysis` attribute of the Perceval
    item returned. To initialize this class, you have to provide
    the local path of a Git repository (URI), a value for
    `git_path`, where the repository will be mirrored, and the path where
    a working tree will be created. The working tree is added to the
    mirror and removed after the analysis is over.

    For each target commit (by default all of them), a checkout version
    of the repository is created at `worktreepath` to ease the analysis.
    Note that you can customize the filter to select commits, by
    redefining the method `_filter_commit(self, commit)`.
    Furthermore, you can plug your analysis by redefining the