more work on base store

pytest.ini

@@ -3,4 +3,5 @@ doctest_optionflags = NORMALIZE_WHITESPACE ELLIPSIS IGNORE_EXCEPTION_DETAIL
 addopts = --durations=10
 filterwarnings =
     error::DeprecationWarning:zarr.*
+    error::UserWarning:zarr.*
     ignore:PY_SSIZE_T_CLEAN will be required.*:DeprecationWarning

zarr/hierarchy.py

@@ -95,8 +95,16 @@ class Group(MutableMapping):
 
     """
 
-    def __init__(self, store, path=None, read_only=False, chunk_store=None,
-                 cache_attrs=True, synchronizer=None):
+    def __init__(
+        self,
+        store,
+        path=None,
+        read_only=False,
+        chunk_store=None,
+        cache_attrs=True,
+        synchronizer=None,
+    ):
+        assert hasattr(store, "listdir")
         self._store = store
         self._chunk_store = chunk_store
         self._path = normalize_storage_path(path)

zarr/storage.py

@@ -121,10 +121,6 @@ def rmdir(store: Store, path: Path = None):
         store.rmdir(path)  # type: ignore
     else:
         # slow version, delete one key at a time
-        warnings.warn(
-            "Store {store} has not `rmdir` method. From zarr 2.5 you may want"
-            "to inherit from `Store`.".format(store=store)
-        )
         _rmdir_from_keys(store, path)
 
 
@@ -176,7 +172,8 @@ def listdir(store: Store, path: Path = None):
         # slow version, iterate through all keys
         warnings.warn(
             "Store {store} has not `listdir` method. From zarr 2.5 you may want"
-            "to inherit from `Store`.".format(store=store)
+            "to inherit from `Store`.".format(store=store),
+            stacklevel=2,
         )
         return _listdir_from_keys(store, path)
 
@@ -2729,7 +2726,7 @@ def __init__(self, store, metadata_key='.zmetadata'):
                                 consolidated_format)
 
         # decode metadata
-        self.meta_store = meta['metadata']
+        self.meta_store = meta["metadata"]
 
     def __getitem__(self, key):
         return self.meta_store[key]