def load(self, filename, create_if_missing=True):
        filename = Path(filename)
        if not filename.exists() and create_if_missing:
            self.load_pip_requirements()
            with filename.open("w") as f:
                f.write(yaml.dump(self.serialized, default_flow_style=False,
                                  encoding=None))
            self.filename = filename
            return self.save(filename)
        with filename.open() as f:
            for group, requirements in yaml.load(f.read()).items():
                for requirement in requirements:
                    self[group].add(Requirement.coerce(requirement))
        self.filename = filename
def test_positional_args(self):
        # see also http://bugs.python.org/issue5042
        class W(Structure):
            _fields_ = [("a", c_int), ("b", c_int)]
        class X(W):
            _fields_ = [("c", c_int)]
        class Y(X):
            pass
        class Z(Y):
            _fields_ = [("d", c_int), ("e", c_int), ("f", c_int)]

        z = Z(1, 2, 3, 4, 5, 6)
        self.assertEqual((z.a, z.b, z.c, z.d, z.e, z.f),
                         (1, 2, 3, 4, 5, 6))
        z = Z(1)
        self.assertEqual((z.a, z.b, z.c, z.d, z.e, z.f),
                         (1, 0, 0, 0, 0, 0))
        self.assertRaises(TypeError, lambda: Z(1, 2, 3, 4, 5, 6, 7))