typing types have the __args__ property. Close pylint-dev/pylint#2419

Author: PCManticore

ChangeLog

@@ -6,6 +6,9 @@ What's New in astroid 2.2.0?
 ============================
 Release Date: TBA
 
+
+* ``typing`` types have the `__args__` property. Close PyCQA/pylint#2419
+
 * Fix a bug where an Attribute used as a base class was triggering a crash
 
   Close #626

astroid/brain/brain_typing.py

@@ -25,6 +25,10 @@ class Meta(type):
     def __getitem__(self, item):
         return self
 
+    @property
+    def __args__(self):
+        return ()
+
 class {0}(metaclass=Meta):
     pass
 """

astroid/tests/unittest_brain.py

@@ -965,6 +965,17 @@ def test_typing_types(self):
             inferred = next(node.infer())
             self.assertIsInstance(inferred, nodes.ClassDef, node.as_string())
 
+    def test_has_dunder_args(self):
+        ast_node = builder.extract_node(
+            """
+        from typing import Union
+        NumericTypes = Union[int, float]
+        NumericTypes.__args__ #@
+        """
+        )
+        inferred = next(ast_node.infer())
+        assert isinstance(inferred, nodes.Tuple)
+
 
 class ReBrainTest(unittest.TestCase):
     def test_regex_flags(self):