sharded store test

Author: JMorado

xarray/tests/test_backends.py

@@ -110,11 +110,26 @@
 
 have_zarr_v3 = False
 try:
-    # as of Zarr v2.13 these imports require environment variable
+    # as of Zarr v2.14 these imports require environment variable
     # ZARR_V3_EXPERIMENTAL_API=1
     from zarr import DirectoryStoreV3, KVStoreV3
 
     have_zarr_v3 = True
+
+    from zarr._storage.v3_storage_transformers import v3_sharding_available
+
+    if v3_sharding_available:
+        # as of Zarr v2.14 these imports require environment variable
+        # ZARR_V3_SHARDING=1
+        # TODO: change import to
+        # from zarr import ShardingStorageTransformer
+        # when ShardingStorageTransformer becomes available at the top-level zarr namespace
+        from zarr._storage.v3_storage_transformers import ShardingStorageTransformer
+
+        have_sharding_v3 = True
+    else:
+        have_sharding_v3 = False
+
 except ImportError:
     KVStoreV3 = None
 
@@ -2660,6 +2675,32 @@ def create_zarr_target(self):
             yield tmp
 
 
+@pytest.mark.skipif(not have_zarr_v3, reason="requires zarr version 3")
+class TestZarrStorageTransformersV3(TestZarrDirectoryStoreV3):
+    @pytest.mark.skipif(not have_sharding_v3, reason="requires sharding")
+    def test_sharding_storage_transformer(self):
+        original = create_test_data()
+        original["var2"].encoding.update(
+            {
+                "chunks": (2, 3),
+                "storage_transformers": [
+                    ShardingStorageTransformer("indexed", chunks_per_shard=(2, 2))
+                ],
+            }
+        )
+
+        original["var3"].encoding.update(
+            {
+                "chunks": (2, 2),
+                "storage_transformers": [
+                    ShardingStorageTransformer("indexed", chunks_per_shard=(2, 2))
+                ],
+            }
+        )
+        with self.roundtrip(original) as ds1:
+            assert_equal(ds1, original)
+
+
 @requires_zarr
 @requires_fsspec
 def test_zarr_storage_options() -> None: