Fix usage of _convert_to_dict to avoid modifying nesting SyncedDict objects when calling items or values

changelog.txt

@@ -19,6 +19,7 @@ Fixed
 +++++
 
  - Fixed issues on Windows with ``H5Store``, project import/export, and operations that move files (#264, #266).
+ - Calling ``items`` or ``values`` on _SyncedDict objects does not mutate nested dictionaries (#234, #269).
 
 
 [1.3.0] -- 2019-12-20

signac/core/synceddict.py

@@ -265,11 +265,11 @@ def keys(self):
 
     def values(self):
         self._synced_load()
-        return self._convert_to_dict(self._data).values()
+        return self._convert_to_dict(self).values()
 
     def items(self):
         self._synced_load()
-        return self._convert_to_dict(self._data).items()
+        return self._convert_to_dict(self).items()
 
     def __repr__(self):
         return repr(self())
@@ -279,7 +279,7 @@ def __str__(self):
 
     def _as_dict(self):
         with self._suspend_sync():
-            return self._convert_to_dict(self._data.copy())
+            return self._convert_to_dict(self)
 
     def __call__(self):
         self._synced_load()

tests/test_synced_attrdict.py

@@ -508,6 +508,18 @@ def test_suspend_sync(self):
         self.assertEqual(len(sad), 1)
         self.assert_only_read()
 
+    def test_nested_types_dict_conversion(self):
+        """Ensure that calling methods like items and values does not
+        change the type of nested dictionaries."""
+        sad = self.get_sad({'a': {'b': 1}})
+        assert type(sad['a']) is SAD
+        sad.items()
+        assert type(sad['a']) is SAD
+        sad.values()
+        assert type(sad['a']) is SAD
+        sad._as_dict()
+        assert type(sad['a']) is SAD
+
 
 if __name__ == '__main__':
     unittest.main()