cpython/Lib/test/test_property.py

# Test case for property
# more tests are in test_descr

import unittest
from test.support import run_unittest

class PropertyBase(Exception):
    pass

class PropertyGet(PropertyBase):
    pass

class PropertySet(PropertyBase):
    pass

class PropertyDel(PropertyBase):
    pass

class BaseClass(object):
    def __init__(self):
        self._spam = 5

    @property
    def spam(self):
        """BaseClass.getter"""
        return self._spam

    @spam.setter
    def spam(self, value):
        self._spam = value

    @spam.deleter
    def spam(self):
        del self._spam

class SubClass(BaseClass):

    @BaseClass.spam.getter
    def spam(self):
        """SubClass.getter"""
        raise PropertyGet(self._spam)

    @spam.setter
    def spam(self, value):
        raise PropertySet(self._spam)

    @spam.deleter
    def spam(self):
        raise PropertyDel(self._spam)

class PropertyDocBase(object):
    _spam = 1
    def _get_spam(self):
        return self._spam
    spam = property(_get_spam, doc="spam spam spam")

class PropertyDocSub(PropertyDocBase):
    @PropertyDocBase.spam.getter
    def spam(self):
        """The decorator does not use this doc string"""
        return self._spam

class PropertySubNewGetter(BaseClass):
    @BaseClass.spam.getter
    def spam(self):
        """new docstring"""
        return 5

class PropertyNewGetter(object):
    @property
    def spam(self):
        """original docstring"""
        return 1
    @spam.getter
    def spam(self):
        """new docstring"""
        return 8

class PropertyTests(unittest.TestCase):
    def test_property_decorator_baseclass(self):
        # see #1620
        base = BaseClass()
        self.assertEqual(base.spam, 5)
        self.assertEqual(base._spam, 5)
        base.spam = 10
        self.assertEqual(base.spam, 10)
        self.assertEqual(base._spam, 10)
        delattr(base, "spam")
        self.assertTrue(not hasattr(base, "spam"))
        self.assertTrue(not hasattr(base, "_spam"))
        base.spam = 20
        self.assertEqual(base.spam, 20)
        self.assertEqual(base._spam, 20)
        self.assertEqual(base.__class__.spam.__doc__, "BaseClass.getter")

    def test_property_decorator_subclass(self):
        # see #1620
        sub = SubClass()
        self.assertRaises(PropertyGet, getattr, sub, "spam")
        self.assertRaises(PropertySet, setattr, sub, "spam", None)
        self.assertRaises(PropertyDel, delattr, sub, "spam")
        self.assertEqual(sub.__class__.spam.__doc__, "SubClass.getter")

    def test_property_decorator_doc(self):
        base = PropertyDocBase()
        sub = PropertyDocSub()
        self.assertEqual(base.__class__.spam.__doc__, "spam spam spam")
        self.assertEqual(sub.__class__.spam.__doc__, "spam spam spam")

    def test_property_getter_doc_override(self):
        newgettersub = PropertySubNewGetter()
        self.assertEqual(newgettersub.spam, 5)
        self.assertEqual(newgettersub.__class__.spam.__doc__, "new docstring")
        newgetter = PropertyNewGetter()
        self.assertEqual(newgetter.spam, 8)
        self.assertEqual(newgetter.__class__.spam.__doc__, "new docstring")


# Issue 5890: subclasses of property do not preserve method __doc__ strings
class PropertySub(property):
    """This is a subclass of property"""

class PropertySubSlots(property):
    """This is a subclass of property that defines __slots__"""
    __slots__ = ()

class PropertySubclassTests(unittest.TestCase):

    def test_docstring_copy(self):
        class Foo(object):
            @PropertySub
            def spam(self):
                """spam wrapped in property subclass"""
                return 1
        self.assertEqual(
            Foo.spam.__doc__,
            "spam wrapped in property subclass")

    def test_slots_docstring_copy_exception(self):
        try:
            class Foo(object):
                @PropertySubSlots
                def spam(self):
                    """Trying to copy this docstring will raise an exception"""
                    return 1
        except AttributeError:
            pass
        else:
            raise Exception("AttributeError not raised")

    def test_property_setter_copies_getter_docstring(self):
        class Foo(object):
            def __init__(self): self._spam = 1
            @PropertySub
            def spam(self):
                """spam wrapped in property subclass"""
                return self._spam
            @spam.setter
            def spam(self, value):
                """this docstring is ignored"""
                self._spam = value
        foo = Foo()
        self.assertEqual(foo.spam, 1)
        foo.spam = 2
        self.assertEqual(foo.spam, 2)
        self.assertEqual(
            Foo.spam.__doc__,
            "spam wrapped in property subclass")
        class FooSub(Foo):
            @Foo.spam.setter
            def spam(self, value):
                """another ignored docstring"""
                self._spam = 'eggs'
        foosub = FooSub()
        self.assertEqual(foosub.spam, 1)
        foosub.spam = 7
        self.assertEqual(foosub.spam, 'eggs')
        self.assertEqual(
            FooSub.spam.__doc__,
            "spam wrapped in property subclass")

    def test_property_new_getter_new_docstring(self):

        class Foo(object):
            @PropertySub
            def spam(self):
                """a docstring"""
                return 1
            @spam.getter
            def spam(self):
                """a new docstring"""
                return 2
        self.assertEqual(Foo.spam.__doc__, "a new docstring")
        class FooBase(object):
            @PropertySub
            def spam(self):
                """a docstring"""
                return 1
        class Foo2(FooBase):
            @FooBase.spam.getter
            def spam(self):
                """a new docstring"""
                return 2
        self.assertEqual(Foo.spam.__doc__, "a new docstring")



def test_main():
    run_unittest(PropertyTests, PropertySubclassTests)

if __name__ == '__main__':
    test_main()