Add tests for conflicting kwargs in ast contructors

Author: Rémi Lapeyre

Lib/test/test_ast.py

@@ -355,6 +355,8 @@ def test_classattrs(self):
 
         self.assertRaises(TypeError, ast.Num, 1, None, 2)
         self.assertRaises(TypeError, ast.Num, 1, None, 2, lineno=0)
+        self.assertRaises(TypeError, ast.Num, 1, n=2)
+        self.assertRaises(TypeError, ast.Constant, 1, value=2)
 
         self.assertEqual(ast.Num(42).n, 42)
         self.assertEqual(ast.Num(4.25).n, 4.25)