attrs/tests/test_slots.py

424 lines
10 KiB
Python

"""
Unit tests for slot-related functionality.
"""
import pytest
import attr
from attr._compat import PY2, PYPY, just_warn, make_set_closure_cell
# Pympler doesn't work on PyPy.
try:
from pympler.asizeof import asizeof
has_pympler = True
except BaseException: # Won't be an import error.
has_pympler = False
@attr.s
class C1(object):
x = attr.ib(validator=attr.validators.instance_of(int))
y = attr.ib()
def method(self):
return self.x
@classmethod
def classmethod(cls):
return "clsmethod"
@staticmethod
def staticmethod():
return "staticmethod"
if not PY2:
def my_class(self):
return __class__ # NOQA: F821
def my_super(self):
"""Just to test out the no-arg super."""
return super().__repr__()
@attr.s(slots=True, hash=True)
class C1Slots(object):
x = attr.ib(validator=attr.validators.instance_of(int))
y = attr.ib()
def method(self):
return self.x
@classmethod
def classmethod(cls):
return "clsmethod"
@staticmethod
def staticmethod():
return "staticmethod"
if not PY2:
def my_class(self):
return __class__ # NOQA: F821
def my_super(self):
"""Just to test out the no-arg super."""
return super().__repr__()
def test_slots_being_used():
"""
The class is really using __slots__.
"""
non_slot_instance = C1(x=1, y="test")
slot_instance = C1Slots(x=1, y="test")
assert "__dict__" not in dir(slot_instance)
assert "__slots__" in dir(slot_instance)
assert "__dict__" in dir(non_slot_instance)
assert "__slots__" not in dir(non_slot_instance)
assert set(["x", "y"]) == set(slot_instance.__slots__)
if has_pympler:
assert asizeof(slot_instance) < asizeof(non_slot_instance)
non_slot_instance.t = "test"
with pytest.raises(AttributeError):
slot_instance.t = "test"
assert 1 == non_slot_instance.method()
assert 1 == slot_instance.method()
assert attr.fields(C1Slots) == attr.fields(C1)
assert attr.asdict(slot_instance) == attr.asdict(non_slot_instance)
def test_basic_attr_funcs():
"""
Comparison, `__eq__`, `__hash__`, `__repr__`, `attrs.asdict` work.
"""
a = C1Slots(x=1, y=2)
b = C1Slots(x=1, y=3)
a_ = C1Slots(x=1, y=2)
# Comparison.
assert b > a
assert a_ == a
# Hashing.
hash(b) # Just to assert it doesn't raise.
# Repr.
assert "C1Slots(x=1, y=2)" == repr(a)
assert {"x": 1, "y": 2} == attr.asdict(a)
def test_inheritance_from_nonslots():
"""
Inheritance from a non-slot class works.
Note that a slots class inheriting from an ordinary class loses most of the
benefits of slots classes, but it should still work.
"""
@attr.s(slots=True, hash=True)
class C2Slots(C1):
z = attr.ib()
c2 = C2Slots(x=1, y=2, z="test")
assert 1 == c2.x
assert 2 == c2.y
assert "test" == c2.z
c2.t = "test" # This will work, using the base class.
assert "test" == c2.t
assert 1 == c2.method()
assert "clsmethod" == c2.classmethod()
assert "staticmethod" == c2.staticmethod()
assert set(["z"]) == set(C2Slots.__slots__)
c3 = C2Slots(x=1, y=3, z="test")
assert c3 > c2
c2_ = C2Slots(x=1, y=2, z="test")
assert c2 == c2_
assert "C2Slots(x=1, y=2, z='test')" == repr(c2)
hash(c2) # Just to assert it doesn't raise.
assert {"x": 1, "y": 2, "z": "test"} == attr.asdict(c2)
def test_nonslots_these():
"""
Enhancing a non-slots class using 'these' works.
This will actually *replace* the class with another one, using slots.
"""
class SimpleOrdinaryClass(object):
def __init__(self, x, y, z):
self.x = x
self.y = y
self.z = z
def method(self):
return self.x
@classmethod
def classmethod(cls):
return "clsmethod"
@staticmethod
def staticmethod():
return "staticmethod"
C2Slots = attr.s(these={"x": attr.ib(), "y": attr.ib(), "z": attr.ib()},
init=False, slots=True, hash=True)(SimpleOrdinaryClass)
c2 = C2Slots(x=1, y=2, z="test")
assert 1 == c2.x
assert 2 == c2.y
assert "test" == c2.z
with pytest.raises(AttributeError):
c2.t = "test" # We have slots now.
assert 1 == c2.method()
assert "clsmethod" == c2.classmethod()
assert "staticmethod" == c2.staticmethod()
assert set(["x", "y", "z"]) == set(C2Slots.__slots__)
c3 = C2Slots(x=1, y=3, z="test")
assert c3 > c2
c2_ = C2Slots(x=1, y=2, z="test")
assert c2 == c2_
assert "SimpleOrdinaryClass(x=1, y=2, z='test')" == repr(c2)
hash(c2) # Just to assert it doesn't raise.
assert {"x": 1, "y": 2, "z": "test"} == attr.asdict(c2)
def test_inheritance_from_slots():
"""
Inheriting from an attr slot class works.
"""
@attr.s(slots=True, hash=True)
class C2Slots(C1Slots):
z = attr.ib()
@attr.s(slots=True, hash=True)
class C2(C1):
z = attr.ib()
c2 = C2Slots(x=1, y=2, z="test")
assert 1 == c2.x
assert 2 == c2.y
assert "test" == c2.z
assert set(["z"]) == set(C2Slots.__slots__)
assert 1 == c2.method()
assert "clsmethod" == c2.classmethod()
assert "staticmethod" == c2.staticmethod()
with pytest.raises(AttributeError):
c2.t = "test"
non_slot_instance = C2(x=1, y=2, z="test")
if has_pympler:
assert asizeof(c2) < asizeof(non_slot_instance)
c3 = C2Slots(x=1, y=3, z="test")
assert c3 > c2
c2_ = C2Slots(x=1, y=2, z="test")
assert c2 == c2_
assert "C2Slots(x=1, y=2, z='test')" == repr(c2)
hash(c2) # Just to assert it doesn't raise.
assert {"x": 1, "y": 2, "z": "test"} == attr.asdict(c2)
def test_bare_inheritance_from_slots():
"""
Inheriting from a bare attr slot class works.
"""
@attr.s(init=False, cmp=False, hash=False, repr=False, slots=True)
class C1BareSlots(object):
x = attr.ib(validator=attr.validators.instance_of(int))
y = attr.ib()
def method(self):
return self.x
@classmethod
def classmethod(cls):
return "clsmethod"
@staticmethod
def staticmethod():
return "staticmethod"
@attr.s(init=False, cmp=False, hash=False, repr=False)
class C1Bare(object):
x = attr.ib(validator=attr.validators.instance_of(int))
y = attr.ib()
def method(self):
return self.x
@classmethod
def classmethod(cls):
return "clsmethod"
@staticmethod
def staticmethod():
return "staticmethod"
@attr.s(slots=True, hash=True)
class C2Slots(C1BareSlots):
z = attr.ib()
@attr.s(slots=True, hash=True)
class C2(C1Bare):
z = attr.ib()
c2 = C2Slots(x=1, y=2, z="test")
assert 1 == c2.x
assert 2 == c2.y
assert "test" == c2.z
assert 1 == c2.method()
assert "clsmethod" == c2.classmethod()
assert "staticmethod" == c2.staticmethod()
with pytest.raises(AttributeError):
c2.t = "test"
non_slot_instance = C2(x=1, y=2, z="test")
if has_pympler:
assert asizeof(c2) < asizeof(non_slot_instance)
c3 = C2Slots(x=1, y=3, z="test")
assert c3 > c2
c2_ = C2Slots(x=1, y=2, z="test")
assert c2 == c2_
assert "C2Slots(x=1, y=2, z='test')" == repr(c2)
hash(c2) # Just to assert it doesn't raise.
assert {"x": 1, "y": 2, "z": "test"} == attr.asdict(c2)
@pytest.mark.skipif(PY2, reason="closure cell rewriting is PY3-only.")
class TestClosureCellRewriting(object):
def test_closure_cell_rewriting(self):
"""
Slot classes support proper closure cell rewriting.
This affects features like `__class__` and the no-arg super().
"""
non_slot_instance = C1(x=1, y="test")
slot_instance = C1Slots(x=1, y="test")
assert non_slot_instance.my_class() is C1
assert slot_instance.my_class() is C1Slots
# Just assert they return something, and not an exception.
assert non_slot_instance.my_super()
assert slot_instance.my_super()
def test_inheritance(self):
"""
Slot classes support proper closure cell rewriting when inheriting.
This affects features like `__class__` and the no-arg super().
"""
@attr.s
class C2(C1):
def my_subclass(self):
return __class__ # NOQA: F821
@attr.s
class C2Slots(C1Slots):
def my_subclass(self):
return __class__ # NOQA: F821
non_slot_instance = C2(x=1, y="test")
slot_instance = C2Slots(x=1, y="test")
assert non_slot_instance.my_class() is C1
assert slot_instance.my_class() is C1Slots
# Just assert they return something, and not an exception.
assert non_slot_instance.my_super()
assert slot_instance.my_super()
assert non_slot_instance.my_subclass() is C2
assert slot_instance.my_subclass() is C2Slots
@pytest.mark.parametrize("slots", [True, False])
def test_cls_static(self, slots):
"""
Slot classes support proper closure cell rewriting for class- and
static methods.
"""
# Python can reuse closure cells, so we create new classes just for
# this test.
@attr.s(slots=slots)
class C:
@classmethod
def clsmethod(cls):
return __class__ # noqa: F821
assert C.clsmethod() is C
@attr.s(slots=slots)
class D:
@staticmethod
def statmethod():
return __class__ # noqa: F821
assert D.statmethod() is D
@pytest.mark.skipif(
PYPY,
reason="ctypes are used only on CPython"
)
def test_missing_ctypes(self, monkeypatch):
"""
Keeps working if ctypes is missing.
A warning is emitted that points to the actual code.
"""
monkeypatch.setattr(attr._compat, "import_ctypes", lambda: None)
func = make_set_closure_cell()
with pytest.warns(RuntimeWarning) as wr:
func()
w = wr.pop()
assert __file__ == w.filename
assert (
"Missing ctypes. Some features like bare super() or accessing "
"__class__ will not work with slots classes.",
) == w.message.args
assert just_warn is func