From c7e6ce3f28f6e6fc743f6ee48f12f918ae0ad7b1 Mon Sep 17 00:00:00 2001
From: Matthias Bussonnier <bussonniermatthias@gmail.com>
Date: Thu, 22 Oct 2020 10:32:03 -0700
Subject: [PATCH] Checking that the store is an instance of dict seem
 incorrect.

Indeed MemoryStore is an instance of mutable mapping that have the same
property as dict, but woudl not be seen as as instance of dict.
---
 zarr/core.py    | 3 ++-
 zarr/storage.py | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/zarr/core.py b/zarr/core.py
index 8727a5deb5..651775e3a3 100644
--- a/zarr/core.py
+++ b/zarr/core.py
@@ -5,6 +5,7 @@
 import operator
 import re
 from functools import reduce
+from collections.abc import MutableMapping
 
 import numpy as np
 from numcodecs.compat import ensure_bytes, ensure_ndarray
@@ -1821,7 +1822,7 @@ def _encode_chunk(self, chunk):
             cdata = chunk
 
         # ensure in-memory data is immutable and easy to compare
-        if isinstance(self.chunk_store, dict):
+        if isinstance(self.chunk_store, MutableMapping):
             cdata = ensure_bytes(cdata)
 
         return cdata
diff --git a/zarr/storage.py b/zarr/storage.py
index 89f85f8eec..2b60c749ee 100644
--- a/zarr/storage.py
+++ b/zarr/storage.py
@@ -176,7 +176,7 @@ def getsize(store, path: Path = None) -> int:
     if hasattr(store, 'getsize'):
         # pass through
         return store.getsize(path)
-    elif isinstance(store, dict):
+    elif isinstance(store, MutableMapping):
         # compute from size of values
         if path in store:
             v = store[path]