def __init__(self, package, version):
        """Construct a new requirement.

        :param package: the package name.
        :param version: a semver compatible version specification.
        """
        self.package = package
        self.version = version
        if self.version and not re.match(r"[<=>~]", version[:2]):
            self.version = "=={}".format(self.version)
def test_base_class_pre_accept_validate_raises_error(self):
        with self.assertRaisesRegex(
            NotImplementedError,
            'Subclasses of BaseSuggestion should implement'
            ' pre_accept_validate.'):
            self.base_suggestion.pre_accept_validate()