def load(self, requirements_file=None):
        """Load or reload requirements from a requirements.txt file.

        :param requirements_file: if not given, the filename used from
            initialization will be read again.
        """
        if requirements_file is None:
            requirements_file = self.filename
            if requirements_file is None:
                raise ValueError("no filename provided")
        elif isinstance(requirements_file, text_type):
            requirements_file = Path(requirements_file)
        self.clear()
        with requirements_file.open() as f:
            self.loads(f.read())

        if isinstance(requirements_file, (text_type, Path)):
            self.filename = requirements_file
def test_methods_etc(self):
        mock_session = Mock()
        mock_session.bind = "the bind"

        sess = scoped_session(lambda: mock_session)

        sess.add("add")
        sess.delete("delete")

        sess.get("Cls", 5)

        eq_(sess.bind, "the bind")

        eq_(
            mock_session.mock_calls,
            [
                mock.call.add("add", _warn=True),
                mock.call.delete("delete"),
                mock.call.get(
                    "Cls",
                    5,
                    options=None,
                    populate_existing=False,
                    with_for_update=None,
                    identity_token=None,
                    execution_options=None,
                ),
            ],
        )

        with mock.patch(
            "sqlalchemy.orm.session.object_session"
        ) as mock_object_session:
            sess.object_session("foo")

        eq_(mock_object_session.mock_calls, [mock.call("foo")])