zipline/tests/utils/test_metautils.py

from zipline.testing.fixtures import ZiplineTestCase
from zipline.testing.predicates import (
    assert_equal,
    assert_is,
    assert_is_instance,
    assert_is_subclass,
    assert_true,
)
from zipline.utils.metautils import compose_types, with_metaclasses


class C(object):
    @staticmethod
    def f():
        return 'C.f'

    def delegate(self):
        return 'C.delegate', super(C, self).delegate()


class D(object):
    @staticmethod
    def f():
        return 'D.f'

    @staticmethod
    def g():
        return 'D.g'

    def delegate(self):
        return 'D.delegate'


class ComposeTypesTestCase(ZiplineTestCase):

    def test_identity(self):
        assert_is(
            compose_types(C),
            C,
            msg='compose_types of a single class should be identity',
        )

    def test_compose(self):
        composed = compose_types(C, D)

        assert_is_subclass(composed, C)
        assert_is_subclass(composed, D)

    def test_compose_mro(self):
        composed = compose_types(C, D)

        assert_equal(composed.f(), C.f())
        assert_equal(composed.g(), D.g())

        assert_equal(composed().delegate(), ('C.delegate', 'D.delegate'))


class M(type):
    def __new__(mcls, name, bases, dict_):
        dict_['M'] = True
        return super(M, mcls).__new__(mcls, name, bases, dict_)


class N(type):
    def __new__(mcls, name, bases, dict_):
        dict_['N'] = True
        return super(N, mcls).__new__(mcls, name, bases, dict_)


class WithMetaclassesTestCase(ZiplineTestCase):
    def test_with_metaclasses_no_subclasses(self):
        class E(with_metaclasses((M, N))):
            pass

        assert_true(E.M)
        assert_true(E.N)

        assert_is_instance(E, M)
        assert_is_instance(E, N)

    def test_with_metaclasses_with_subclasses(self):
        class E(with_metaclasses((M, N), C, D)):
            pass

        assert_true(E.M)
        assert_true(E.N)

        assert_is_instance(E, M)
        assert_is_instance(E, N)
        assert_is_subclass(E, C)
        assert_is_subclass(E, D)