expose erasability of zipstore

zarr/storage.py

@@ -1547,6 +1547,8 @@ class also supports the context manager protocol, which ensures the ``close()``
 
     """
 
+    _erasable = False
+
     def __init__(self, path, compression=zipfile.ZIP_STORED, allowZip64=True, mode='a'):
 
         # store properties

zarr/tests/test_storage.py

@@ -400,13 +400,13 @@ def test_hierarchy(self):
                 pass
 
         # test rmdir (optional)
-        if hasattr(store, 'rmdir'):
-            store.rmdir('c/e')
-            assert 'c/d' in store
-            assert 'c/e/f' not in store
-            assert 'c/e/g' not in store
-            store.rmdir('c')
-            assert 'c/d' not in store
+        if store.is_erasable():
+            store.rmdir("c/e")
+            assert "c/d" in store
+            assert "c/e/f" not in store
+            assert "c/e/g" not in store
+            store.rmdir("c")
+            assert "c/d" not in store
             store.rmdir()
             assert 'a' not in store
             assert 'b' not in store