cover ZipStore with mode "r"

Author: alimanfoo

zarr/storage.py

@@ -16,6 +16,7 @@
 from zarr.meta import encode_array_metadata, encode_group_metadata
 from zarr.compat import PY2, binary_type
 from zarr.codecs import codec_registry
+from zarr.errors import PermissionError
 
 
 array_meta_key = '.zarray'
@@ -734,13 +735,10 @@ def __getitem__(self, key):
                 return f.read()
 
     def __setitem__(self, key, value):
+        if self.mode == 'r':
+            raise PermissionError('mapping is read-only')
         value = ensure_bytes(value)
-        if self.mode in {'w', 'a', 'x'}:
-            mode = 'a'
-        else:
-            # let zipfile raise an error when trying to write
-            mode = 'r'
-        with zipfile.ZipFile(self.path, mode=mode,
+        with zipfile.ZipFile(self.path, mode='a',
                              compression=self.compression,
                              allowZip64=self.allowZip64) as zf:
             zf.writestr(key, value)

zarr/tests/test_storage.py

@@ -21,6 +21,7 @@
 from zarr.compat import text_type
 from zarr.storage import default_compressor
 from zarr.codecs import Zlib, Blosc
+from zarr.errors import PermissionError
 
 
 class StoreTests(object):
@@ -634,6 +635,13 @@ def create_store(self):
         store = ZipStore(path)
         return store
 
+    def test_mode(self):
+        store = ZipStore('example.zip', mode='w')
+        store['foo'] = b'bar'
+        store = ZipStore('example.zip', mode='r')
+        with assert_raises(PermissionError):
+            store['foo'] = b'bar'
+
 
 def test_getsize():
     store = dict()