path: root/tests/test_object_model.py

# Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
# For details: https://github.com/pylint-dev/astroid/blob/main/LICENSE
# Copyright (c) https://github.com/pylint-dev/astroid/blob/main/CONTRIBUTORS.txt

import unittest
import xml

import pytest

import astroid
from astroid import bases, builder, nodes, objects, test_utils, util
from astroid.const import PY311_PLUS
from astroid.exceptions import InferenceError

try:
    import six  # type: ignore[import]  # pylint: disable=unused-import

    HAS_SIX = True
except ImportError:
    HAS_SIX = False


class InstanceModelTest(unittest.TestCase):
    def test_instance_special_model(self) -> None:
        ast_nodes = builder.extract_node(
            """
        class A:
            "test"
            def __init__(self):
                self.a = 42
        a = A()
        a.__class__ #@
        a.__module__ #@
        a.__doc__ #@
        a.__dict__ #@
        """,
            module_name="fake_module",
        )
        assert isinstance(ast_nodes, list)
        cls = next(ast_nodes[0].infer())
        self.assertIsInstance(cls, astroid.ClassDef)
        self.assertEqual(cls.name, "A")

        module = next(ast_nodes[1].infer())
        self.assertIsInstance(module, astroid.Const)
        self.assertEqual(module.value, "fake_module")

        doc = next(ast_nodes[2].infer())
        self.assertIsInstance(doc, astroid.Const)
        self.assertEqual(doc.value, "test")

        dunder_dict = next(ast_nodes[3].infer())
        self.assertIsInstance(dunder_dict, astroid.Dict)
        attr = next(dunder_dict.getitem(astroid.Const("a")).infer())
        self.assertIsInstance(attr, astroid.Const)
        self.assertEqual(attr.value, 42)

    @pytest.mark.xfail(reason="Instance lookup cannot override object model")
    def test_instance_local_attributes_overrides_object_model(self):
        # The instance lookup needs to be changed in order for this to work.
        ast_node = builder.extract_node(
            """
        class A:
            @property
            def __dict__(self):
                  return []
        A().__dict__
        """
        )
        inferred = next(ast_node.infer())
        self.assertIsInstance(inferred, astroid.List)
        self.assertEqual(inferred.elts, [])


class BoundMethodModelTest(unittest.TestCase):
    def test_bound_method_model(self) -> None:
        ast_nodes = builder.extract_node(
            """
        class A:
            def test(self): pass
        a = A()
        a.test.__func__ #@
        a.test.__self__ #@
        """
        )
        assert isinstance(ast_nodes, list)
        func = next(ast_nodes[0].infer())
        self.assertIsInstance(func, astroid.FunctionDef)
        self.assertEqual(func.name, "test")

        self_ = next(ast_nodes[1].infer())
        self.assertIsInstance(self_, astroid.Instance)
        self.assertEqual(self_.name, "A")


class UnboundMethodModelTest(unittest.TestCase):
    def test_unbound_method_model(self) -> None:
        ast_nodes = builder.extract_node(
            """
        class A:
            def test(self): pass
        t = A.test
        t.__class__ #@
        t.__func__ #@
        t.__self__ #@
        t.im_class #@
        t.im_func #@
        t.im_self #@
        """
        )
        assert isinstance(ast_nodes, list)
        cls = next(ast_nodes[0].infer())
        self.assertIsInstance(cls, astroid.ClassDef)
        unbound_name = "function"

        self.assertEqual(cls.name, unbound_name)

        func = next(ast_nodes[1].infer())
        self.assertIsInstance(func, astroid.FunctionDef)
        self.assertEqual(func.name, "test")

        self_ = next(ast_nodes[2].infer())
        self.assertIsInstance(self_, astroid.Const)
        self.assertIsNone(self_.value)

        self.assertEqual(cls.name, next(ast_nodes[3].infer()).name)
        self.assertEqual(func, next(ast_nodes[4].infer()))
        self.assertIsNone(next(ast_nodes[5].infer()).value)


class ClassModelTest(unittest.TestCase):
    def test_priority_to_local_defined_values(self) -> None:
        ast_node = builder.extract_node(
            """
        class A:
            __doc__ = "first"
        A.__doc__ #@
        """
        )
        inferred = next(ast_node.infer())
        self.assertIsInstance(inferred, astroid.Const)
        self.assertEqual(inferred.value, "first")

    def test_class_model_correct_mro_subclasses_proxied(self) -> None:
        ast_nodes = builder.extract_node(
            """
        class A(object):
            pass
        A.mro #@
        A.__subclasses__ #@
        """
        )
        for node in ast_nodes:
            inferred = next(node.infer())
            self.assertIsInstance(inferred, astroid.BoundMethod)
            self.assertIsInstance(inferred._proxied, astroid.FunctionDef)
            self.assertIsInstance(inferred.bound, astroid.ClassDef)
            self.assertEqual(inferred.bound.name, "type")

    def test_class_model(self) -> None:
        ast_nodes = builder.extract_node(
            """
        class A(object):
            "test"

        class B(A): pass
        class C(A): pass

        A.__module__ #@
        A.__name__ #@
        A.__qualname__ #@
        A.__doc__ #@
        A.__mro__ #@
        A.mro() #@
        A.__bases__ #@
        A.__class__ #@
        A.__dict__ #@
        A.__subclasses__() #@
        """,
            module_name="fake_module",
        )
        assert isinstance(ast_nodes, list)
        module = next(ast_nodes[0].infer())
        self.assertIsInstance(module, astroid.Const)
        self.assertEqual(module.value, "fake_module")

        name = next(ast_nodes[1].infer())
        self.assertIsInstance(name, astroid.Const)
        self.assertEqual(name.value, "A")

        qualname = next(ast_nodes[2].infer())
        self.assertIsInstance(qualname, astroid.Const)
        self.assertEqual(qualname.value, "fake_module.A")

        doc = next(ast_nodes[3].infer())
        self.assertIsInstance(doc, astroid.Const)
        self.assertEqual(doc.value, "test")

        mro = next(ast_nodes[4].infer())
        self.assertIsInstance(mro, astroid.Tuple)
        self.assertEqual([cls.name for cls in mro.elts], ["A", "object"])

        called_mro = next(ast_nodes[5].infer())
        self.assertEqual(called_mro.elts, mro.elts)

        base_nodes = next(ast_nodes[6].infer())
        self.assertIsInstance(base_nodes, astroid.Tuple)
        self.assertEqual([cls.name for cls in base_nodes.elts], ["object"])

        cls = next(ast_nodes[7].infer())
        self.assertIsInstance(cls, astroid.ClassDef)
        self.assertEqual(cls.name, "type")

        cls_dict = next(ast_nodes[8].infer())
        self.assertIsInstance(cls_dict, astroid.Dict)

        subclasses = next(ast_nodes[9].infer())
        self.assertIsInstance(subclasses, astroid.List)
        self.assertEqual([cls.name for cls in subclasses.elts], ["B", "C"])


class ModuleModelTest(unittest.TestCase):
    def test_priority_to_local_defined_values(self) -> None:
        ast_node = astroid.parse(
            """
        __file__ = "mine"
        """
        )
        file_value = next(ast_node.igetattr("__file__"))
        self.assertIsInstance(file_value, astroid.Const)
        self.assertEqual(file_value.value, "mine")

    def test__path__not_a_package(self) -> None:
        ast_node = builder.extract_node(
            """
        import sys
        sys.__path__ #@
        """
        )
        with self.assertRaises(InferenceError):
            next(ast_node.infer())

    def test_module_model(self) -> None:
        ast_nodes = builder.extract_node(
            """
        import xml
        xml.__path__ #@
        xml.__name__ #@
        xml.__doc__ #@
        xml.__file__ #@
        xml.__spec__ #@
        xml.__loader__ #@
        xml.__cached__ #@
        xml.__package__ #@
        xml.__dict__ #@
        xml.__init__ #@
        xml.__new__ #@

        xml.__subclasshook__ #@
        xml.__str__ #@
        xml.__sizeof__ #@
        xml.__repr__ #@
        xml.__reduce__ #@

        xml.__setattr__ #@
        xml.__reduce_ex__ #@
        xml.__lt__ #@
        xml.__eq__ #@
        xml.__gt__ #@
        xml.__format__ #@
        xml.__delattr___ #@
        xml.__getattribute__ #@
        xml.__hash__ #@
        xml.__dir__ #@
        xml.__call__ #@
        xml.__closure__ #@
        """
        )
        assert isinstance(ast_nodes, list)
        path = next(ast_nodes[0].infer())
        self.assertIsInstance(path, astroid.List)
        self.assertIsInstance(path.elts[0], astroid.Const)
        self.assertEqual(path.elts[0].value, xml.__path__[0])

        name = next(ast_nodes[1].infer())
        self.assertIsInstance(name, astroid.Const)
        self.assertEqual(name.value, "xml")

        doc = next(ast_nodes[2].infer())
        self.assertIsInstance(doc, astroid.Const)
        self.assertEqual(doc.value, xml.__doc__)

        file_ = next(ast_nodes[3].infer())
        self.assertIsInstance(file_, astroid.Const)
        self.assertEqual(file_.value, xml.__file__.replace(".pyc", ".py"))

        for ast_node in ast_nodes[4:7]:
            inferred = next(ast_node.infer())
            self.assertIs(inferred, astroid.Uninferable)

        package = next(ast_nodes[7].infer())
        self.assertIsInstance(package, astroid.Const)
        self.assertEqual(package.value, "xml")

        dict_ = next(ast_nodes[8].infer())
        self.assertIsInstance(dict_, astroid.Dict)

        init_ = next(ast_nodes[9].infer())
        assert isinstance(init_, bases.BoundMethod)
        init_result = next(
            init_.infer_call_result(
                nodes.Call(
                    parent=None,
                    lineno=None,
                    col_offset=None,
                    end_lineno=None,
                    end_col_offset=None,
                )
            )
        )
        assert isinstance(init_result, nodes.Const)
        assert init_result.value is None

        new_ = next(ast_nodes[10].infer())
        assert isinstance(new_, bases.BoundMethod)

        # The following nodes are just here for theoretical completeness,
        # and they either return Uninferable or raise InferenceError.
        for ast_node in ast_nodes[11:28]:
            with pytest.raises(InferenceError):
                next(ast_node.infer())


class FunctionModelTest(unittest.TestCase):
    def test_partial_descriptor_support(self) -> None:
        bound, result = builder.extract_node(
            """
        class A(object): pass
        def test(self): return 42
        f = test.__get__(A(), A)
        f #@
        f() #@
        """
        )
        bound = next(bound.infer())
        self.assertIsInstance(bound, astroid.BoundMethod)
        self.assertEqual(bound._proxied._proxied.name, "test")
        result = next(result.infer())
        self.assertIsInstance(result, astroid.Const)
        self.assertEqual(result.value, 42)

    def test___get__has_extra_params_defined(self) -> None:
        node = builder.extract_node(
            """
        def test(self): return 42
        test.__get__
        """
        )
        inferred = next(node.infer())
        self.assertIsInstance(inferred, astroid.BoundMethod)
        args = inferred.args.args
        self.assertEqual(len(args), 2)
        self.assertEqual([arg.name for arg in args], ["self", "type"])

    @test_utils.require_version(minver="3.8")
    def test__get__and_positional_only_args(self):
        node = builder.extract_node(
            """
        def test(self, a, b, /, c): return a + b + c
        test.__get__(test)(1, 2, 3)
        """
        )
        inferred = next(node.infer())
        assert inferred is util.Uninferable

    @pytest.mark.xfail(reason="Descriptors cannot infer what self is")
    def test_descriptor_not_inferrring_self(self):
        # We can't infer __get__(X, Y)() when the bounded function
        # uses self, because of the tree's parent not being propagating good enough.
        result = builder.extract_node(
            """
        class A(object):
            x = 42
        def test(self): return self.x
        f = test.__get__(A(), A)
        f() #@
        """
        )
        result = next(result.infer())
        self.assertIsInstance(result, astroid.Const)
        self.assertEqual(result.value, 42)

    def test_descriptors_binding_invalid(self) -> None:
        ast_nodes = builder.extract_node(
            """
        class A: pass
        def test(self): return 42
        test.__get__()() #@
        test.__get__(2, 3, 4) #@
        """
        )
        for node in ast_nodes:
            with self.assertRaises(InferenceError):
                next(node.infer())

    def test_descriptor_error_regression(self) -> None:
        """Make sure the following code does node cause an exception."""
        node = builder.extract_node(
            """
        class MyClass:
            text = "MyText"

            def mymethod1(self):
                return self.text

            def mymethod2(self):
                return self.mymethod1.__get__(self, MyClass)


        cl = MyClass().mymethod2()()
        cl #@
        """
        )
        assert isinstance(node, nodes.NodeNG)
        [const] = node.inferred()
        assert const.value == "MyText"

    def test_function_model(self) -> None:
        ast_nodes = builder.extract_node(
            '''
        def func(a=1, b=2):
            """test"""
        func.__name__ #@
        func.__doc__ #@
        func.__qualname__ #@
        func.__module__  #@
        func.__defaults__ #@
        func.__dict__ #@
        func.__globals__ #@
        func.__code__ #@
        func.__closure__ #@
        func.__init__ #@
        func.__new__ #@

        func.__subclasshook__ #@
        func.__str__ #@
        func.__sizeof__ #@
        func.__repr__ #@
        func.__reduce__ #@

        func.__reduce_ex__ #@
        func.__lt__ #@
        func.__eq__ #@
        func.__gt__ #@
        func.__format__ #@
        func.__delattr___ #@
        func.__getattribute__ #@
        func.__hash__ #@
        func.__dir__ #@
        func.__class__ #@

        func.__setattr__ #@
        ''',
            module_name="fake_module",
        )
        assert isinstance(ast_nodes, list)
        name = next(ast_nodes[0].infer())
        self.assertIsInstance(name, astroid.Const)
        self.assertEqual(name.value, "func")

        doc = next(ast_nodes[1].infer())
        self.assertIsInstance(doc, astroid.Const)
        self.assertEqual(doc.value, "test")

        qualname = next(ast_nodes[2].infer())
        self.assertIsInstance(qualname, astroid.Const)
        self.assertEqual(qualname.value, "fake_module.func")

        module = next(ast_nodes[3].infer())
        self.assertIsInstance(module, astroid.Const)
        self.assertEqual(module.value, "fake_module")

        defaults = next(ast_nodes[4].infer())
        self.assertIsInstance(defaults, astroid.Tuple)
        self.assertEqual([default.value for default in defaults.elts], [1, 2])

        dict_ = next(ast_nodes[5].infer())
        self.assertIsInstance(dict_, astroid.Dict)

        globals_ = next(ast_nodes[6].infer())
        self.assertIsInstance(globals_, astroid.Dict)

        for ast_node in ast_nodes[7:9]:
            self.assertIs(next(ast_node.infer()), astroid.Uninferable)

        init_ = next(ast_nodes[9].infer())
        assert isinstance(init_, bases.BoundMethod)
        init_result = next(
            init_.infer_call_result(
                nodes.Call(
                    parent=None,
                    lineno=None,
                    col_offset=None,
                    end_lineno=None,
                    end_col_offset=None,
                )
            )
        )
        assert isinstance(init_result, nodes.Const)
        assert init_result.value is None

        new_ = next(ast_nodes[10].infer())
        assert isinstance(new_, bases.BoundMethod)

        # The following nodes are just here for theoretical completeness,
        # and they either return Uninferable or raise InferenceError.
        for ast_node in ast_nodes[11:26]:
            inferred = next(ast_node.infer())
            assert inferred is util.Uninferable

        for ast_node in ast_nodes[26:27]:
            with pytest.raises(InferenceError):
                inferred = next(ast_node.infer())

    def test_empty_return_annotation(self) -> None:
        ast_node = builder.extract_node(
            """
        def test(): pass
        test.__annotations__
        """
        )
        annotations = next(ast_node.infer())
        self.assertIsInstance(annotations, astroid.Dict)
        self.assertEqual(len(annotations.items), 0)

    def test_builtin_dunder_init_does_not_crash_when_accessing_annotations(
        self,
    ) -> None:
        ast_node = builder.extract_node(
            """
        class Class:
            @classmethod
            def class_method(cls):
                cls.__init__.__annotations__ #@
        """
        )
        inferred = next(ast_node.infer())
        self.assertIsInstance(inferred, astroid.Dict)
        self.assertEqual(len(inferred.items), 0)

    def test_annotations_kwdefaults(self) -> None:
        ast_node = builder.extract_node(
            """
        def test(a: 1, *args: 2, f:4='lala', **kwarg:3)->2: pass
        test.__annotations__ #@
        test.__kwdefaults__ #@
        """
        )
        annotations = next(ast_node[0].infer())
        self.assertIsInstance(annotations, astroid.Dict)
        self.assertIsInstance(
            annotations.getitem(astroid.Const("return")), astroid.Const
        )
        self.assertEqual(annotations.getitem(astroid.Const("return")).value, 2)
        self.assertIsInstance(annotations.getitem(astroid.Const("a")), astroid.Const)
        self.assertEqual(annotations.getitem(astroid.Const("a")).value, 1)
        self.assertEqual(annotations.getitem(astroid.Const("args")).value, 2)
        self.assertEqual(annotations.getitem(astroid.Const("kwarg")).value, 3)

        self.assertEqual(annotations.getitem(astroid.Const("f")).value, 4)

        kwdefaults = next(ast_node[1].infer())
        self.assertIsInstance(kwdefaults, astroid.Dict)
        # self.assertEqual(kwdefaults.getitem('f').value, 'lala')

    @test_utils.require_version(minver="3.8")
    def test_annotation_positional_only(self):
        ast_node = builder.extract_node(
            """
        def test(a: 1, b: 2, /, c: 3): pass
        test.__annotations__ #@
        """
        )
        annotations = next(ast_node.infer())
        self.assertIsInstance(annotations, astroid.Dict)

        self.assertIsInstance(annotations.getitem(astroid.Const("a")), astroid.Const)
        self.assertEqual(annotations.getitem(astroid.Const("a")).value, 1)
        self.assertEqual(annotations.getitem(astroid.Const("b")).value, 2)
        self.assertEqual(annotations.getitem(astroid.Const("c")).value, 3)


class TestContextManagerModel:
    def test_model(self) -> None:
        """We use a generator to test this model."""
        ast_nodes = builder.extract_node(
            """
        def test():
           "a"
           yield

        gen = test()
        gen.__enter__ #@
        gen.__exit__ #@
        """
        )
        assert isinstance(ast_nodes, list)

        enter = next(ast_nodes[0].infer())
        assert isinstance(enter, astroid.BoundMethod)
        # Test that the method is correctly bound
        assert isinstance(enter.bound, bases.Generator)
        assert enter.bound._proxied.qname() == "builtins.generator"
        # Test that thet FunctionDef accepts no arguments except self
        # NOTE: This probably shouldn't be double proxied, but this is a
        # quirck of the current model implementations.
        assert isinstance(enter._proxied._proxied, nodes.FunctionDef)
        assert len(enter._proxied._proxied.args.args) == 1
        assert enter._proxied._proxied.args.args[0].name == "self"

        exit_node = next(ast_nodes[1].infer())
        assert isinstance(exit_node, astroid.BoundMethod)
        # Test that the FunctionDef accepts the arguments as defiend in the ObjectModel
        assert isinstance(exit_node._proxied._proxied, nodes.FunctionDef)
        assert len(exit_node._proxied._proxied.args.args) == 4
        assert exit_node._proxied._proxied.args.args[0].name == "self"
        assert exit_node._proxied._proxied.args.args[1].name == "exc_type"
        assert exit_node._proxied._proxied.args.args[2].name == "exc_value"
        assert exit_node._proxied._proxied.args.args[3].name == "traceback"


class GeneratorModelTest(unittest.TestCase):
    def test_model(self) -> None:
        ast_nodes = builder.extract_node(
            """
        def test():
           "a"
           yield

        gen = test()
        gen.__name__ #@
        gen.__doc__ #@
        gen.gi_code #@
        gen.gi_frame #@
        gen.send #@
        gen.__enter__ #@
        gen.__exit__ #@
        """
        )
        assert isinstance(ast_nodes, list)
        name = next(ast_nodes[0].infer())
        self.assertEqual(name.value, "test")

        doc = next(ast_nodes[1].infer())
        self.assertEqual(doc.value, "a")

        gi_code = next(ast_nodes[2].infer())
        self.assertIsInstance(gi_code, astroid.ClassDef)
        self.assertEqual(gi_code.name, "gi_code")

        gi_frame = next(ast_nodes[3].infer())
        self.assertIsInstance(gi_frame, astroid.ClassDef)
        self.assertEqual(gi_frame.name, "gi_frame")

        send = next(ast_nodes[4].infer())
        self.assertIsInstance(send, astroid.BoundMethod)

        enter = next(ast_nodes[5].infer())
        assert isinstance(enter, astroid.BoundMethod)

        exit_node = next(ast_nodes[6].infer())
        assert isinstance(exit_node, astroid.BoundMethod)


class ExceptionModelTest(unittest.TestCase):
    @staticmethod
    def test_valueerror_py3() -> None:
        ast_nodes = builder.extract_node(
            """
        try:
            x[42]
        except ValueError as err:
           err.args #@
           err.__traceback__ #@

           err.message #@
        """
        )
        assert isinstance(ast_nodes, list)
        args = next(ast_nodes[0].infer())
        assert isinstance(args, astroid.Tuple)
        tb = next(ast_nodes[1].infer())
        # Python 3.11: If 'contextlib' is loaded, '__traceback__'
        # could be set inside '__exit__' method in
        # which case 'err.__traceback__' will be 'Uninferable'
        try:
            assert isinstance(tb, astroid.Instance)
            assert tb.name == "traceback"
        except AssertionError:
            if PY311_PLUS:
                assert tb == util.Uninferable
            else:
                raise

        with pytest.raises(InferenceError):
            next(ast_nodes[2].infer())

    def test_syntax_error(self) -> None:
        ast_node = builder.extract_node(
            """
        try:
            x[42]
        except SyntaxError as err:
           err.text #@
        """
        )
        inferred = next(ast_node.infer())
        assert isinstance(inferred, astroid.Const)

    @unittest.skipIf(HAS_SIX, "This test fails if the six library is installed")
    def test_oserror(self) -> None:
        ast_nodes = builder.extract_node(
            """
        try:
            raise OSError("a")
        except OSError as err:
           err.filename #@
           err.filename2 #@
           err.errno #@
        """
        )
        expected_values = ["", "", 0]
        for node, value in zip(ast_nodes, expected_values):
            inferred = next(node.infer())
            assert isinstance(inferred, astroid.Const)
            assert inferred.value == value

    def test_unicodedecodeerror(self) -> None:
        code = """
        try:
            raise UnicodeDecodeError("utf-8", "blob", 0, 1, "reason")
        except UnicodeDecodeError as error:
            error.object[:1] #@
        """
        node = builder.extract_node(code)
        inferred = next(node.infer())
        assert isinstance(inferred, astroid.Const)

    def test_import_error(self) -> None:
        ast_nodes = builder.extract_node(
            """
        try:
            raise ImportError("a")
        except ImportError as err:
           err.name #@
           err.path #@
        """
        )
        for node in ast_nodes:
            inferred = next(node.infer())
            assert isinstance(inferred, astroid.Const)
            assert inferred.value == ""

    def test_exception_instance_correctly_instantiated(self) -> None:
        ast_node = builder.extract_node(
            """
        try:
            raise ImportError("a")
        except ImportError as err:
           err #@
        """
        )
        inferred = next(ast_node.infer())
        assert isinstance(inferred, astroid.Instance)
        cls = next(inferred.igetattr("__class__"))
        assert isinstance(cls, astroid.ClassDef)


class DictObjectModelTest(unittest.TestCase):
    def test__class__(self) -> None:
        ast_node = builder.extract_node("{}.__class__")
        inferred = next(ast_node.infer())
        self.assertIsInstance(inferred, astroid.ClassDef)
        self.assertEqual(inferred.name, "dict")

    def test_attributes_inferred_as_methods(self) -> None:
        ast_nodes = builder.extract_node(
            """
        {}.values #@
        {}.items #@
        {}.keys #@
        """
        )
        for node in ast_nodes:
            inferred = next(node.infer())
            self.assertIsInstance(inferred, astroid.BoundMethod)

    def test_wrapper_objects_for_dict_methods_python3(self) -> None:
        ast_nodes = builder.extract_node(
            """
        {1:1, 2:3}.values() #@
        {1:1, 2:3}.keys() #@
        {1:1, 2:3}.items() #@
        """
        )
        assert isinstance(ast_nodes, list)
        values = next(ast_nodes[0].infer())
        self.assertIsInstance(values, objects.DictValues)
        self.assertEqual([elt.value for elt in values.elts], [1, 3])
        keys = next(ast_nodes[1].infer())
        self.assertIsInstance(keys, objects.DictKeys)
        self.assertEqual([elt.value for elt in keys.elts], [1, 2])
        items = next(ast_nodes[2].infer())
        self.assertIsInstance(items, objects.DictItems)


class TestExceptionInstanceModel:
    """Tests for ExceptionInstanceModel."""

    def test_str_argument_not_required(self) -> None:
        """Test that the first argument to an exception does not need to be a str."""
        ast_node = builder.extract_node(
            """
        BaseException() #@
        """
        )
        args: nodes.Tuple = next(ast_node.infer()).getattr("args")[0]
        # BaseException doesn't have any required args, not even a string
        assert not args.elts


class LruCacheModelTest(unittest.TestCase):
    def test_lru_cache(self) -> None:
        ast_nodes = builder.extract_node(
            """
        import functools
        class Foo(object):
            @functools.lru_cache()
            def foo():
                pass
        f = Foo()
        f.foo.cache_clear #@
        f.foo.__wrapped__ #@
        f.foo.cache_info() #@
        """
        )
        assert isinstance(ast_nodes, list)
        cache_clear = next(ast_nodes[0].infer())
        self.assertIsInstance(cache_clear, astroid.BoundMethod)
        wrapped = next(ast_nodes[1].infer())
        self.assertIsInstance(wrapped, astroid.FunctionDef)
        self.assertEqual(wrapped.name, "foo")
        cache_info = next(ast_nodes[2].infer())
        self.assertIsInstance(cache_info, astroid.Instance)