def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
def test_reserve_unreserve_volume(self):
        """Test reserving and unreserving volume"""
        # Mark volume as reserved.
        self.volumes_client.reserve_volume(self.volume['id'])
        # To get the volume info
        body = self.volumes_client.show_volume(self.volume['id'])['volume']
        self.assertIn('attaching', body['status'])
        # Unmark volume as reserved.
        self.volumes_client.unreserve_volume(self.volume['id'])
        # To get the volume info
        body = self.volumes_client.show_volume(self.volume['id'])['volume']
        self.assertIn('available', body['status'])