allow roundtripping the BytesCodec

changes/3417.bugfix.rst

@@ -0,0 +1 @@
+Allow roundtripping ``BytesCodec`` instances to / from dict.

src/zarr/codecs/bytes.py

@@ -50,6 +50,7 @@ def from_dict(cls, data: dict[str, JSON]) -> Self:
             data, "bytes", require_configuration=False
         )
         configuration_parsed = configuration_parsed or {}
+        configuration_parsed.setdefault("endian", None)
         return cls(**configuration_parsed)  # type: ignore[arg-type]
 
     def to_dict(self) -> dict[str, JSON]:

tests/test_codecs/test_endian.py → tests/test_codecs/test_bytes.py

@@ -1,11 +1,11 @@
-from typing import Literal
+from typing import Any, Literal
 
 import numpy as np
 import pytest
 
 import zarr
 from zarr.abc.store import Store
-from zarr.codecs import BytesCodec
+from zarr.codecs import BytesCodec, Endian
 from zarr.storage import StorePath
 
 from .test_codecs import _AsyncArrayProxy
@@ -58,3 +58,47 @@ async def test_endian_write(
     await _AsyncArrayProxy(a)[:, :].set(data)
     readback_data = await _AsyncArrayProxy(a)[:, :].get()
     assert np.array_equal(data, readback_data)
+
+
+@pytest.mark.parametrize(
+    ("endian", "expected"),
+    [
+        pytest.param(
+            "little", {"name": "bytes", "configuration": {"endian": "little"}}, id="little"
+        ),
+        pytest.param("big", {"name": "bytes", "configuration": {"endian": "big"}}, id="big"),
+        pytest.param(None, {"name": "bytes"}, id="missing"),
+    ],
+)
+def test_to_dict(endian: str, expected: dict[str, Any]) -> None:
+    codec = BytesCodec(endian=endian)
+
+    actual = codec.to_dict()
+
+    assert actual == expected
+
+
+@pytest.mark.parametrize(
+    ("mapping", "expected"),
+    [
+        pytest.param(
+            {"name": "bytes", "configuration": {"endian": "little"}}, Endian.little, id="little"
+        ),
+        pytest.param({"name": "bytes", "configuration": {"endian": "big"}}, Endian.big, id="big"),
+        pytest.param({"name": "bytes"}, None, id="missing"),
+    ],
+)
+def test_from_dict(mapping: dict[str, Any], expected: Endian | None) -> None:
+    actual = BytesCodec.from_dict(mapping)
+
+    assert actual.endian == expected
+
+
+@pytest.mark.parametrize("endian", ["little", "big", pytest.param(None, id="missing")])
+def test_roundtrip(endian: str | None) -> None:
+    codec = BytesCodec(endian=endian)
+
+    encoded = codec.to_dict()
+    roundtripped = BytesCodec.from_dict(encoded)
+
+    assert codec == roundtripped