Method test_no_unhashable_default

Lib/test/test_dataclasses/__init__.py:584–608

(self)

        self.assertNotEqual(C(3, 10), C(4, 10))

    def test_no_unhashable_default(self):
        # See bpo-44674.
        class Unhashable:
            __hash__ = None

        unhashable_re = 'mutable default .* for field a is not allowed'
        with self.assertRaisesRegex(ValueError, unhashable_re):
            @dataclass
            class A:
                a: dict = {}

        with self.assertRaisesRegex(ValueError, unhashable_re):
            @dataclass
            class A:
                a: Any = Unhashable()

        # Make sure that the machinery looking for hashability is using the
        # class's __hash__, not the instance's __hash__.
        with self.assertRaisesRegex(ValueError, unhashable_re):
            unhashable = Unhashable()
            # This shouldn't make the variable hashable.
            unhashable.__hash__ = lambda: 0
            @dataclass
            class A:
                a: Any = unhashable

    def test_hash_field_rules(self):
        # Test all 6 cases of: