Create ContextManagerModel and let GeneratorModel inherit

ChangeLog

@@ -16,6 +16,10 @@ Release date: TBA
 
   Closes PyCQA/pylint#7488.
 
+* Create ``ContextManagerModel`` and let ``GeneratorModel`` inherit from it.
+
+  Refs PyCQA/pylint#2567
+
 
 What's New in astroid 2.12.11?
 ==============================

astroid/interpreter/objectmodel.py

@@ -588,6 +588,48 @@ def attr___self__(self):
     attr_im_self = attr___self__
 
 
+class ContextManagerModel(ObjectModel):
+    """Model for context managers.
+
+    Based on 3.3.9 of the Data Model documentation:
+    https://docs.python.org/3/reference/datamodel.html#with-statement-context-managers
+    """
+
+    @property
+    def attr___enter__(self) -> bases.BoundMethod:
+        """Representation of the base implementation of __enter__.
+
+        As per Python documentation:
+        Enter the runtime context related to this object. The with statement
+        will bind this method's return value to the target(s) specified in the
+        as clause of the statement, if any.
+        """
+        node: nodes.FunctionDef = builder.extract_node("""def __enter__(self): ...""")
+        # We set the parent as being the ClassDef of 'object' as that
+        # is where this method originally comes from
+        node.parent = AstroidManager().builtins_module["object"]
+
+        return bases.BoundMethod(proxy=node, bound=_get_bound_node(self))
+
+    @property
+    def attr___exit__(self) -> bases.BoundMethod:
+        """Representation of the base implementation of __exit__.
+
+        As per Python documentation:
+        Exit the runtime context related to this object. The parameters describe the
+        exception that caused the context to be exited. If the context was exited
+        without an exception, all three arguments will be None.
+        """
+        node: nodes.FunctionDef = builder.extract_node(
+            """def __exit__(self, exc_type, exc_value, traceback): ..."""
+        )
+        # We set the parent as being the ClassDef of 'object' as that
+        # is where this method originally comes from
+        node.parent = AstroidManager().builtins_module["object"]
+
+        return bases.BoundMethod(proxy=node, bound=_get_bound_node(self))
+
+
 class BoundMethodModel(FunctionModel):
     @property
     def attr___func__(self):
@@ -598,7 +640,7 @@ def attr___self__(self):
         return self._instance.bound
 
 
-class GeneratorModel(FunctionModel):
+class GeneratorModel(FunctionModel, ContextManagerModel):
     def __new__(cls, *args, **kwargs):
         # Append the values from the GeneratorType unto this object.
         ret = super().__new__(cls, *args, **kwargs)

tests/unittest_object_model.py

@@ -571,6 +571,45 @@ def test(a: 1, b: 2, /, c: 3): pass
         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(
@@ -585,6 +624,8 @@ def test():
         gen.gi_code #@
         gen.gi_frame #@
         gen.send #@
+        gen.__enter__ #@
+        gen.__exit__ #@
         """
         )
         assert isinstance(ast_nodes, list)
@@ -605,6 +646,12 @@ def test():
         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