test for v2-style error when creating an object array without an object codec

Author: d-v-b

src/zarr/core/array.py

@@ -4721,7 +4721,7 @@ def default_filters_v2(dtype: ZDType[Any, Any]) -> tuple[numcodecs.abc.Codec] |
 
             return (VLenUTF8(),)
         else:
-            msg = f"Data type {dtype} requires an unknown object codec: {dtype.object_codec_id}"
+            msg = f"Data type {dtype} requires an unknown object codec: {dtype.object_codec_id!r}"
             raise ValueError(msg)
     return None
 
@@ -4795,7 +4795,7 @@ def _parse_chunk_encoding_v2(
             elif isinstance(dtype, VariableLengthBytes):
                 codec_name = "the numcodecs.VLenBytes codec"
             else:
-                codec_name = "an unknown object codec"
+                codec_name = f"an unknown object codec with id {dtype.object_codec_id!r}"
             msg = (
                 f"Data type {dtype} requires {codec_name}, "
                 "but no such codec was specified in the filters or compressor parameters for "

tests/test_array.py

@@ -41,17 +41,22 @@
 from zarr.core.chunk_grids import _auto_partition
 from zarr.core.chunk_key_encodings import ChunkKeyEncodingParams
 from zarr.core.common import JSON, MemoryOrder, ZarrFormat
-from zarr.core.dtype import parse_data_type
-from zarr.core.dtype.common import ENDIANNESS_STR, EndiannessStr
-from zarr.core.dtype.npy.common import NUMPY_ENDIANNESS_STR, endianness_from_numpy_str
-from zarr.core.dtype.npy.float import Float32, Float64
-from zarr.core.dtype.npy.int import Int16, UInt8
-from zarr.core.dtype.npy.string import VariableLengthUTF8
-from zarr.core.dtype.npy.structured import (
+from zarr.core.dtype import (
+    DateTime64,
+    Float32,
+    Float64,
+    Int16,
     Structured,
+    TimeDelta64,
+    UInt8,
+    VariableLengthBytes,
+    VariableLengthUTF8,
+    ZDType,
+    parse_data_type,
 )
-from zarr.core.dtype.npy.time import DateTime64, TimeDelta64
-from zarr.core.dtype.wrapper import ZDType
+from zarr.core.dtype.common import ENDIANNESS_STR, EndiannessStr
+from zarr.core.dtype.npy.common import NUMPY_ENDIANNESS_STR, endianness_from_numpy_str
+from zarr.core.dtype.npy.string import UTF8Base
 from zarr.core.group import AsyncGroup
 from zarr.core.indexing import BasicIndexer, ceildiv
 from zarr.core.metadata.v2 import ArrayV2Metadata
@@ -1850,3 +1855,41 @@ def test_array_repr(store: Store) -> None:
     dtype = "uint8"
     arr = zarr.create_array(store, shape=shape, dtype=dtype)
     assert str(arr) == f"<Array {store} shape={shape} dtype={dtype}>"
+
+
+class UnknownObjectDtype(UTF8Base[np.dtypes.ObjectDType]):
+    object_codec_id = "unknown"  # type: ignore[assignment]
+
+    def to_native_dtype(self) -> np.dtypes.ObjectDType:
+        """
+        Create a NumPy object dtype from this VariableLengthUTF8 ZDType.
+
+        Returns
+        -------
+        np.dtypes.ObjectDType
+            The NumPy object dtype.
+        """
+        return np.dtype("o")
+
+
+@pytest.mark.parametrize(
+    "dtype", [VariableLengthUTF8(), VariableLengthBytes(), UnknownObjectDtype()]
+)
+def test_chunk_encoding_no_object_codec_errors(dtype: ZDType[Any, Any]) -> None:
+    """
+    Test that a valuerror is raised when checking the chunk encoding for a v2 array with a
+    data type that requires an object codec, but where no object codec is specified
+    """
+    if isinstance(dtype, VariableLengthUTF8):
+        codec_name = "the numcodecs.VLenUTF8 codec"
+    elif isinstance(dtype, VariableLengthBytes):
+        codec_name = "the numcodecs.VLenBytes codec"
+    else:
+        codec_name = f"an unknown object codec with id {dtype.object_codec_id!r}"
+    msg = (
+        f"Data type {dtype} requires {codec_name}, "
+        "but no such codec was specified in the filters or compressor parameters for "
+        "this array. "
+    )
+    with pytest.raises(ValueError, match=re.escape(msg)):
+        _parse_chunk_encoding_v2(filters=None, compressor=None, dtype=dtype)