bpo-35960: Fix dataclasses.field throwing away empty metadata. (GH-11815) (GH-11826)
(cherry picked from commit b01786c8812c4cc24dd561b5941025bdd6f444c0)
Co-authored-by: Christopher Hunt <chrahunt@gmail.com>
diff --git a/Lib/test/test_dataclasses.py b/Lib/test/test_dataclasses.py
index ff6060c..9c83459 100755
--- a/Lib/test/test_dataclasses.py
+++ b/Lib/test/test_dataclasses.py
@@ -1737,23 +1737,33 @@
i: int = field(metadata=0)
# Make sure an empty dict works.
+ d = {}
@dataclass
class C:
- i: int = field(metadata={})
+ i: int = field(metadata=d)
self.assertFalse(fields(C)[0].metadata)
self.assertEqual(len(fields(C)[0].metadata), 0)
+ # Update should work (see bpo-35960).
+ d['foo'] = 1
+ self.assertEqual(len(fields(C)[0].metadata), 1)
+ self.assertEqual(fields(C)[0].metadata['foo'], 1)
with self.assertRaisesRegex(TypeError,
'does not support item assignment'):
fields(C)[0].metadata['test'] = 3
# Make sure a non-empty dict works.
+ d = {'test': 10, 'bar': '42', 3: 'three'}
@dataclass
class C:
- i: int = field(metadata={'test': 10, 'bar': '42', 3: 'three'})
+ i: int = field(metadata=d)
self.assertEqual(len(fields(C)[0].metadata), 3)
self.assertEqual(fields(C)[0].metadata['test'], 10)
self.assertEqual(fields(C)[0].metadata['bar'], '42')
self.assertEqual(fields(C)[0].metadata[3], 'three')
+ # Update should work.
+ d['foo'] = 1
+ self.assertEqual(len(fields(C)[0].metadata), 4)
+ self.assertEqual(fields(C)[0].metadata['foo'], 1)
with self.assertRaises(KeyError):
# Non-existent key.
fields(C)[0].metadata['baz']