allow missing 'configuration' in chunk_key_encoding

[joshmoore]

Similar to #2024, the "configuration" key of chunk_key_encoding is optional. If it's missing, a ValueError is raised:

  File "/Users/jamoore/opt/challenge/zarr-python/src/zarr/common.py", line 130, in parse_named_configuration
    raise ValueError(f"Named configuration does not have a 'configuration' key. Got {data}.")
ValueError: Named configuration does not have a 'configuration' key. Got {'name': 'default'}.

cc: @d-v-b

Edit: data was originally written by tensorstore

[joshmoore]

diff --git a/src/zarr/common.py b/src/zarr/common.py
index 342db141..1534fa16 100644
--- a/src/zarr/common.py
+++ b/src/zarr/common.py
@@ -127,6 +127,7 @@ def parse_named_configuration(
     if "configuration" in data:
         configuration_parsed = parse_configuration(data["configuration"])
     elif require_configuration:
+        return name_parsed, {}

works around the immediate issue

[d-v-b]

yes that would be an immediate fix. longer term we should remove parse_named_configuration and replace it with something like parse_chunk_key_encoding, parse_chunk_grid, etc, that each can handle a NamedConfiguration as input.

[joshmoore]

The same testing for #2029 applies:

• this error was occurring with 3.0.0a0
• but not with 3.0.0b1

🎉