bpo-43764: Add match_args=False parameter to dataclass decorator and to make_dataclasses function. (GH-25337)

Add match_args=False parameter to dataclass decorator and to make_dataclass function.

1 files changed, 41 insertions, 0 deletions

diff --git a/Lib/test/test_dataclasses.py b/Lib/test/test_dataclasses.py
index 29f29e1e689..4beed69e45b 100644
--- a/Lib/test/test_dataclasses.py
+++ b/Lib/test/test_dataclasses.py
@@ -3440,6 +3440,47 @@ class TestMatchArgs(unittest.TestCase):
             c: int
         self.assertEqual(X.__match_args__, ("a", "b", "c"))
 
+    def test_match_args_argument(self):
+        @dataclass(match_args=False)
+        class X:
+            a: int
+        self.assertNotIn('__match_args__', X.__dict__)
+
+        @dataclass(match_args=False)
+        class Y:
+            a: int
+            __match_args__ = ('b',)
+        self.assertEqual(Y.__match_args__, ('b',))
+
+        @dataclass(match_args=False)
+        class Z(Y):
+            z: int
+        self.assertEqual(Z.__match_args__, ('b',))
+
+        # Ensure parent dataclass __match_args__ is seen, if child class
+        # specifies match_args=False.
+        @dataclass
+        class A:
+            a: int
+            z: int
+        @dataclass(match_args=False)
+        class B(A):
+            b: int
+        self.assertEqual(B.__match_args__, ('a', 'z'))
+
+    def test_make_dataclasses(self):
+        C = make_dataclass('C', [('x', int), ('y', int)])
+        self.assertEqual(C.__match_args__, ('x', 'y'))
+
+        C = make_dataclass('C', [('x', int), ('y', int)], match_args=True)
+        self.assertEqual(C.__match_args__, ('x', 'y'))
+
+        C = make_dataclass('C', [('x', int), ('y', int)], match_args=False)
+        self.assertNotIn('__match__args__', C.__dict__)
+
+        C = make_dataclass('C', [('x', int), ('y', int)], namespace={'__match_args__': ('z',)})
+        self.assertEqual(C.__match_args__, ('z',))
+
 
 if __name__ == '__main__':
     unittest.main()