Always return dict for custom metadata (#132)

* always return dict from TargetMeta.custom and custom_internal
* fix tests accordingly

src/tufup/common.py

@@ -21,8 +21,8 @@ class CustomMetadataDict(TypedDict):
  used by tufup internally
  """
 
- user: Optional[dict]
- tufup: Optional[dict]
+ user: dict
+ tufup: dict
 
 
 def _immutable(value):
@@ -79,19 +79,19 @@ def __init__(
  logger.critical(
  f'invalid filename "{self.filename}": whitespace not allowed'
  )
- self._custom = custom
+ self._custom = custom or dict(user=dict(), tufup=dict())
 
  @property
- def custom(self) -> Optional[dict]:
- """returns user-specified custom metadata"""
+ def custom(self) -> dict:
+ """returns user-specified custom metadata dict"""
  return self._get_custom_metadata('user')
 
  @property
- def custom_internal(self) -> Optional[dict]:
- """returns tufup-internal custom metadata"""
+ def custom_internal(self) -> dict:
+ """returns tufup-internal custom metadata dict"""
  return self._get_custom_metadata('tufup')
 
- def _get_custom_metadata(self, key: str) -> Optional[dict]:
+ def _get_custom_metadata(self, _key: str) -> dict:
  """
  get custom metadata in a backward-compatible manner (older versions did not
  distinguish between user-specified and internal metadata)
@@ -100,7 +100,8 @@ def _get_custom_metadata(self, key: str) -> Optional[dict]:
  # check dict keys for backward compatibility
  if get_type_hints(CustomMetadataDict).keys() != self._custom.keys():
  return self._custom
- return self._custom.get(key)
+ return self._custom.get(_key)
+ return dict()
 
  def __str__(self):
  return str(self.target_path_str)

tests/test_common.py

@@ -24,6 +24,7 @@ def test_immutable(self):
  bytearray(b'b'),
  dict(a=1),
  [dict(a=[dict(c={1})], b=bytearray(b'd'))],
+ dict(a=dict(b=dict(c=dict()))),
  ]
  for case in cases:
  with self.subTest(msg=case):
@@ -66,7 +67,16 @@ def test_str(self):
 
  def test_hashable(self):
  obj = TargetMeta()
- self.assertEqual(obj.__hash__(), hash(tuple(vars(obj).items())))
+ try:
+ obj.__hash__()
+ except Exception as e:
+ self.fail(f'__hash__ failed unexpectedly: {e}')
+ expected_obj_hashable = (
+ ('target_path_str', 'None-None.tar.gz'),
+ ('path', pathlib.Path('None-None.tar.gz')),
+ ('_custom', (('user', ()), ('tufup', ()))),
+ )
+ self.assertEqual(hash(expected_obj_hashable), obj.__hash__())
  # we can use the obj as a set member or as dict key
  self.assertEqual({obj, obj}, {obj})
 
@@ -171,8 +181,11 @@ def test_custom_metadata_backward_compatibility(self):
 
  def test_custom_metadata_not_specified(self):
  target_meta = TargetMeta()
- self.assertIsNone(target_meta.custom)
- self.assertIsNone(target_meta.custom_internal)
+ self.assertIsInstance(target_meta.custom, dict)
+ self.assertIsInstance(target_meta.custom_internal, dict)
+ # user overrides _custom attr
+ target_meta._custom = None
+ self.assertIsInstance(target_meta.custom, dict)
 
 
 class PatcherTests(TempDirTestCase):