move warning into to_dict

Author: slevang

src/zarr/codecs/numcodecs/_codecs.py

@@ -102,12 +102,6 @@ def __init__(self, **codec_config: JSON) -> None:
             )  # pragma: no cover
 
         object.__setattr__(self, "codec_config", codec_config)
-        warn(
-            "Numcodecs codecs are not in the Zarr version 3 specification and "
-            "may not be supported by other zarr implementations.",
-            category=ZarrUserWarning,
-            stacklevel=2,
-        )
 
     @cached_property
     def _codec(self) -> Numcodec:
@@ -119,6 +113,12 @@ def from_dict(cls, data: dict[str, JSON]) -> Self:
         return cls(**codec_config)
 
     def to_dict(self) -> dict[str, JSON]:
+        warn(
+            "Numcodecs codecs are not in the Zarr version 3 specification and "
+            "may not be supported by other zarr implementations.",
+            category=ZarrUserWarning,
+            stacklevel=2,
+        )
         codec_config = self.codec_config.copy()
         codec_config.pop("id", None)
         return {

tests/test_cli/test_migrate_v3.py

@@ -524,8 +524,7 @@ def test_migrate_incorrect_filter(local_store: LocalStore) -> None:
         fill_value=0,
     )
 
-    with pytest.warns(UserWarning, match=NUMCODECS_USER_WARNING):
-        result = runner.invoke(cli.app, ["migrate", "v3", str(local_store.root)])
+    result = runner.invoke(cli.app, ["migrate", "v3", str(local_store.root)])
 
     assert result.exit_code == 1
     assert isinstance(result.exception, TypeError)
@@ -548,8 +547,7 @@ def test_migrate_incorrect_compressor(local_store: LocalStore) -> None:
         fill_value=0,
     )
 
-    with pytest.warns(UserWarning, match=NUMCODECS_USER_WARNING):
-        result = runner.invoke(cli.app, ["migrate", "v3", str(local_store.root)])
+    result = runner.invoke(cli.app, ["migrate", "v3", str(local_store.root)])
 
     assert result.exit_code == 1
     assert isinstance(result.exception, TypeError)

tests/test_codecs/test_numcodecs.py

@@ -2,6 +2,7 @@
 
 import contextlib
 import pickle
+import warnings
 from typing import TYPE_CHECKING, Any
 
 import numpy as np
@@ -164,8 +165,7 @@ def test_generic_filter(
 
     a[:, :] = data.copy()
     with codec_conf():
-        with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
-            b = open_array(a.store, mode="r")
+        b = open_array(a.store, mode="r")
     np.testing.assert_array_equal(data, b[:, :])
 
 
@@ -183,8 +183,7 @@ def test_generic_filter_bitround() -> None:
         )
 
     a[:, :] = data.copy()
-    with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
-        b = open_array(a.store, mode="r")
+    b = open_array(a.store, mode="r")
     assert np.allclose(data, b[:, :], atol=0.1)
 
 
@@ -202,8 +201,7 @@ def test_generic_filter_quantize() -> None:
         )
 
     a[:, :] = data.copy()
-    with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
-        b = open_array(a.store, mode="r")
+    b = open_array(a.store, mode="r")
     assert np.allclose(data, b[:, :], atol=0.001)
 
 
@@ -222,20 +220,18 @@ def test_generic_filter_packbits() -> None:
         )
 
     a[:, :] = data.copy()
-    with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
-        b = open_array(a.store, mode="r")
+    b = open_array(a.store, mode="r")
     np.testing.assert_array_equal(data, b[:, :])
 
-    with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
-        with pytest.raises(ValueError, match=".*requires bool dtype.*"):
-            create_array(
-                {},
-                shape=data.shape,
-                chunks=(16, 16),
-                dtype="uint32",
-                fill_value=0,
-                filters=[_numcodecs.PackBits()],
-            )
+    with pytest.raises(ValueError, match=".*requires bool dtype.*"):
+        create_array(
+            {},
+            shape=data.shape,
+            chunks=(16, 16),
+            dtype="uint32",
+            fill_value=0,
+            filters=[_numcodecs.PackBits()],
+        )
 
 
 @pytest.mark.parametrize(
@@ -251,8 +247,7 @@ def test_generic_filter_packbits() -> None:
 def test_generic_checksum(codec_class: type[_numcodecs._NumcodecsBytesBytesCodec]) -> None:
     # Check if the codec is available in numcodecs
     try:
-        with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
-            codec_class()._codec  # noqa: B018
+        codec_class()._codec  # noqa: B018
     except UnknownCodecError as e:  # pragma: no cover
         pytest.skip(f"{codec_class.codec_name} is not available in numcodecs: {e}")
 
@@ -270,16 +265,14 @@ def test_generic_checksum(codec_class: type[_numcodecs._NumcodecsBytesBytesCodec
 
     a[:, :] = data.copy()
     with codec_conf():
-        with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
-            b = open_array(a.store, mode="r")
+        b = open_array(a.store, mode="r")
     np.testing.assert_array_equal(data, b[:, :])
 
 
 @pytest.mark.parametrize("codec_class", [_numcodecs.PCodec, _numcodecs.ZFPY])
 def test_generic_bytes_codec(codec_class: type[_numcodecs._NumcodecsArrayBytesCodec]) -> None:
     try:
-        with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
-            codec_class()._codec  # noqa: B018
+        codec_class()._codec  # noqa: B018
     except ValueError as e:  # pragma: no cover
         if "codec not available" in str(e):
             pytest.xfail(f"{codec_class.codec_name} is not available: {e}")
@@ -321,21 +314,47 @@ def test_delta_astype() -> None:
 
     a[:, :] = data.copy()
     with codec_conf():
-        with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
-            b = open_array(a.store, mode="r")
+        b = open_array(a.store, mode="r")
     np.testing.assert_array_equal(data, b[:, :])
 
 
 def test_repr() -> None:
-    with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
-        codec = _numcodecs.LZ4(level=5)
+    codec = _numcodecs.LZ4(level=5)
     assert repr(codec) == "LZ4(codec_name='numcodecs.lz4', codec_config={'level': 5})"
 
 
 def test_to_dict() -> None:
+    codec = _numcodecs.LZ4(level=5)
+    with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
+        assert codec.to_dict() == {"name": "numcodecs.lz4", "configuration": {"level": 5}}
+
+
+def test_warn_on_write_not_read() -> None:
+    data = np.arange(0, 256, dtype="uint16").reshape((16, 16))
+
     with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
-        codec = _numcodecs.LZ4(level=5)
-    assert codec.to_dict() == {"name": "numcodecs.lz4", "configuration": {"level": 5}}
+        a = create_array(
+            {},
+            shape=data.shape,
+            chunks=(16, 16),
+            dtype=data.dtype,
+            fill_value=0,
+            compressors=[_numcodecs.Zstd(level=1)],
+        )
+
+    a[:, :] = data.copy()
+    with codec_conf():
+        with warnings.catch_warnings(record=True) as caught:
+            warnings.simplefilter("always")
+            b = open_array(a.store, mode="r")
+
+    np.testing.assert_array_equal(data, b[:, :])
+    assert not [
+        warning
+        for warning in caught
+        if issubclass(warning.category, ZarrUserWarning)
+        and "Numcodecs codecs are not in the Zarr version 3 specification" in str(warning.message)
+    ]
 
 
 @pytest.mark.parametrize(
@@ -367,8 +386,7 @@ def test_to_dict() -> None:
 def test_codecs_pickleable(codec_cls: type[_numcodecs._NumcodecsCodec]) -> None:
     # Check if the codec is available in numcodecs
     try:
-        with pytest.warns(ZarrUserWarning, match=EXPECTED_WARNING_STR):
-            codec = codec_cls()
+        codec = codec_cls()
     except UnknownCodecError as e:  # pragma: no cover
         pytest.skip(f"{codec_cls.codec_name} is not available in numcodecs: {e}")