Deprecate undocumented predicates from the utils module

itemadapter/adapter.py

@@ -10,10 +10,6 @@
     _is_attrs_class,
     _is_dataclass,
     _is_pydantic_model,
-    is_attrs_instance,
-    is_dataclass_instance,
-    is_pydantic_instance,
-    is_scrapy_item,
 )
 
 
@@ -111,7 +107,7 @@ def __init__(self, item: Any) -> None:
 
     @classmethod
     def is_item(cls, item: Any) -> bool:
-        return is_attrs_instance(item)
+        return _is_attrs_class(item) and not isinstance(item, type)
 
     @classmethod
     def is_item_class(cls, item_class: type) -> bool:
@@ -137,7 +133,7 @@ def __init__(self, item: Any) -> None:
 
     @classmethod
     def is_item(cls, item: Any) -> bool:
-        return is_dataclass_instance(item)
+        return _is_dataclass(item) and not isinstance(item, type)
 
     @classmethod
     def is_item_class(cls, item_class: type) -> bool:
@@ -157,10 +153,6 @@ class PydanticAdapter(AdapterInterface):
 
     item: Any
 
-    @classmethod
-    def is_item(cls, item: Any) -> bool:
-        return is_pydantic_instance(item)
-
     @classmethod
     def is_item_class(cls, item_class: type) -> bool:
         return _is_pydantic_model(item_class)
@@ -233,10 +225,6 @@ def field_names(self) -> KeysView:
 
 
 class ScrapyItemAdapter(_MixinDictScrapyItemAdapter, AdapterInterface):
-    @classmethod
-    def is_item(cls, item: Any) -> bool:
-        return is_scrapy_item(item)
-
     @classmethod
     def is_item_class(cls, item_class: type) -> bool:
         return issubclass(item_class, _get_scrapy_item_classes())

itemadapter/utils.py

@@ -1,21 +1,28 @@
+import warnings
+
 from types import MappingProxyType
 from typing import Any
 
 
+__all__ = ["is_item", "get_field_meta_from_class"]
+
+
 def _get_scrapy_item_classes() -> tuple:
     try:
         import scrapy
     except ImportError:
         return ()
     else:
         try:
-            _base_item_cls = getattr(scrapy.item, "_BaseItem", scrapy.item.BaseItem)  # deprecated
+            # handle deprecated base classes
+            _base_item_cls = getattr(scrapy.item, "_BaseItem", scrapy.item.BaseItem)
             return (scrapy.item.Item, _base_item_cls)
         except AttributeError:
             return (scrapy.item.Item,)
 
 
 def _is_dataclass(obj: Any) -> bool:
+    """In py36, this returns False if the "dataclasses" backport module is not installed."""
     try:
         import dataclasses
     except ImportError:
@@ -69,42 +76,6 @@ def _get_pydantic_model_metadata(item_model: Any, field_name: str) -> MappingPro
     return MappingProxyType(metadata)
 
 
-def is_dataclass_instance(obj: Any) -> bool:
-    """Return True if the given object is a dataclass object, False otherwise.
-
-    In py36, this function returns False if the "dataclasses" backport is not available.
-
-    Taken from https://docs.python.org/3/library/dataclasses.html#dataclasses.is_dataclass.
-    """
-    return _is_dataclass(obj) and not isinstance(obj, type)
-
-
-def is_pydantic_instance(obj: Any) -> bool:
-    """Return True if the given object is a Pydantic model, False otherwise."""
-    return _is_pydantic_model(type(obj)) and not isinstance(obj, type)
-
-
-def is_attrs_instance(obj: Any) -> bool:
-    """Return True if the given object is a attrs-based object, False otherwise."""
-    return _is_attrs_class(obj) and not isinstance(obj, type)
-
-
-def is_scrapy_item(obj: Any) -> bool:
-    """Return True if the given object is a Scrapy item, False otherwise."""
-    try:
-        import scrapy
-    except ImportError:
-        return False
-    if isinstance(obj, scrapy.item.Item):
-        return True
-    try:
-        # handle deprecated BaseItem
-        BaseItem = getattr(scrapy.item, "_BaseItem", scrapy.item.BaseItem)
-        return isinstance(obj, BaseItem)
-    except AttributeError:
-        return False
-
-
 def is_item(obj: Any) -> bool:
     """Return True if the given object belongs to one of the supported types, False otherwise.
 
@@ -133,3 +104,54 @@ def get_field_meta_from_class(item_class: type, field_name: str) -> MappingProxy
     from itemadapter.adapter import ItemAdapter
 
     return ItemAdapter.get_field_meta_from_class(item_class, field_name)
+
+
+# deprecated
+
+
+def is_dataclass_instance(obj: Any) -> bool:
+    warnings.warn(
+        "itemadapter.utils.is_dataclass_instance is deprecated"
+        " and it will be removed in a future version",
+        category=DeprecationWarning,
+        stacklevel=2,
+    )
+    from itemadapter.adapter import DataclassAdapter
+
+    return DataclassAdapter.is_item(obj)
+
+
+def is_attrs_instance(obj: Any) -> bool:
+    warnings.warn(
+        "itemadapter.utils.is_attrs_instance is deprecated"
+        " and it will be removed in a future version",
+        category=DeprecationWarning,
+        stacklevel=2,
+    )
+    from itemadapter.adapter import AttrsAdapter
+
+    return AttrsAdapter.is_item(obj)
+
+
+def is_pydantic_instance(obj: Any) -> bool:
+    warnings.warn(
+        "itemadapter.utils.is_pydantic_instance is deprecated"
+        " and it will be removed in a future version",
+        category=DeprecationWarning,
+        stacklevel=2,
+    )
+    from itemadapter.adapter import PydanticAdapter
+
+    return PydanticAdapter.is_item(obj)
+
+
+def is_scrapy_item(obj: Any) -> bool:
+    warnings.warn(
+        "itemadapter.utils.is_scrapy_item is deprecated"
+        " and it will be removed in a future version",
+        category=DeprecationWarning,
+        stacklevel=2,
+    )
+    from itemadapter.adapter import ScrapyItemAdapter
+
+    return ScrapyItemAdapter.is_item(obj)

tests/__init__.py

@@ -1,6 +1,14 @@
+import importlib
 from typing import Optional
 
-from itemadapter.adapter import ItemAdapter
+from itemadapter import ItemAdapter
+
+
+def mocked_import(name, *args, **kwargs):
+    """Allow only internal itemadapter imports."""
+    if name.split(".")[0] == "itemadapter":
+        return importlib.__import__(name, *args, **kwargs)
+    raise ImportError(name)
 
 
 try:

tests/test_adapter_attrs.py

@@ -0,0 +1,69 @@
+import unittest
+import warnings
+from types import MappingProxyType
+from unittest import mock
+
+from itemadapter.adapter import AttrsAdapter
+from itemadapter.utils import get_field_meta_from_class
+
+from tests import (
+    AttrsItem,
+    DataClassItem,
+    PydanticModel,
+    ScrapyItem,
+    ScrapySubclassedItem,
+    mocked_import,
+)
+
+
+class AttrsTestCase(unittest.TestCase):
+    def test_false(self):
+        self.assertFalse(AttrsAdapter.is_item(int))
+        self.assertFalse(AttrsAdapter.is_item(sum))
+        self.assertFalse(AttrsAdapter.is_item(1234))
+        self.assertFalse(AttrsAdapter.is_item(object()))
+        self.assertFalse(AttrsAdapter.is_item(ScrapyItem()))
+        self.assertFalse(AttrsAdapter.is_item(DataClassItem()))
+        self.assertFalse(AttrsAdapter.is_item(PydanticModel()))
+        self.assertFalse(AttrsAdapter.is_item(ScrapySubclassedItem()))
+        self.assertFalse(AttrsAdapter.is_item("a string"))
+        self.assertFalse(AttrsAdapter.is_item(b"some bytes"))
+        self.assertFalse(AttrsAdapter.is_item({"a": "dict"}))
+        self.assertFalse(AttrsAdapter.is_item(["a", "list"]))
+        self.assertFalse(AttrsAdapter.is_item(("a", "tuple")))
+        self.assertFalse(AttrsAdapter.is_item({"a", "set"}))
+        self.assertFalse(AttrsAdapter.is_item(AttrsItem))
+
+    @unittest.skipIf(not AttrsItem, "attrs module is not available")
+    @mock.patch("builtins.__import__", mocked_import)
+    def test_module_not_available(self):
+        self.assertFalse(AttrsAdapter.is_item(AttrsItem(name="asdf", value=1234)))
+        with self.assertRaises(TypeError, msg="AttrsItem is not a valid item class"):
+            get_field_meta_from_class(AttrsItem, "name")
+
+    @unittest.skipIf(not AttrsItem, "attrs module is not available")
+    def test_true(self):
+        self.assertTrue(AttrsAdapter.is_item(AttrsItem()))
+        self.assertTrue(AttrsAdapter.is_item(AttrsItem(name="asdf", value=1234)))
+        # field metadata
+        self.assertEqual(
+            get_field_meta_from_class(AttrsItem, "name"), MappingProxyType({"serializer": str})
+        )
+        self.assertEqual(
+            get_field_meta_from_class(AttrsItem, "value"), MappingProxyType({"serializer": int})
+        )
+        with self.assertRaises(KeyError, msg="AttrsItem does not support field: non_existent"):
+            get_field_meta_from_class(AttrsItem, "non_existent")
+
+    def test_deprecated_is_instance(self):
+        from itemadapter.utils import is_attrs_instance
+
+        with warnings.catch_warnings(record=True) as caught:
+            is_attrs_instance(1)
+            self.assertEqual(len(caught), 1)
+            self.assertTrue(issubclass(caught[0].category, DeprecationWarning))
+            self.assertEqual(
+                "itemadapter.utils.is_attrs_instance is deprecated"
+                " and it will be removed in a future version",
+                str(caught[0].message),
+            )

tests/test_adapter_dataclasses.py

@@ -0,0 +1,70 @@
+import unittest
+import warnings
+from types import MappingProxyType
+from unittest import mock
+
+from itemadapter.adapter import DataclassAdapter
+from itemadapter.utils import get_field_meta_from_class
+
+from tests import (
+    AttrsItem,
+    DataClassItem,
+    PydanticModel,
+    ScrapyItem,
+    ScrapySubclassedItem,
+    mocked_import,
+)
+
+
+class DataclassTestCase(unittest.TestCase):
+    def test_false(self):
+        self.assertFalse(DataclassAdapter.is_item(int))
+        self.assertFalse(DataclassAdapter.is_item(sum))
+        self.assertFalse(DataclassAdapter.is_item(1234))
+        self.assertFalse(DataclassAdapter.is_item(object()))
+        self.assertFalse(DataclassAdapter.is_item(ScrapyItem()))
+        self.assertFalse(DataclassAdapter.is_item(AttrsItem()))
+        self.assertFalse(DataclassAdapter.is_item(PydanticModel()))
+        self.assertFalse(DataclassAdapter.is_item(ScrapySubclassedItem()))
+        self.assertFalse(DataclassAdapter.is_item("a string"))
+        self.assertFalse(DataclassAdapter.is_item(b"some bytes"))
+        self.assertFalse(DataclassAdapter.is_item({"a": "dict"}))
+        self.assertFalse(DataclassAdapter.is_item(["a", "list"]))
+        self.assertFalse(DataclassAdapter.is_item(("a", "tuple")))
+        self.assertFalse(DataclassAdapter.is_item({"a", "set"}))
+        self.assertFalse(DataclassAdapter.is_item(DataClassItem))
+
+    @unittest.skipIf(not DataClassItem, "dataclasses module is not available")
+    @mock.patch("builtins.__import__", mocked_import)
+    def test_module_not_available(self):
+        self.assertFalse(DataclassAdapter.is_item(DataClassItem(name="asdf", value=1234)))
+        with self.assertRaises(TypeError, msg="DataClassItem is not a valid item class"):
+            get_field_meta_from_class(DataClassItem, "name")
+
+    @unittest.skipIf(not DataClassItem, "dataclasses module is not available")
+    def test_true(self):
+        self.assertTrue(DataclassAdapter.is_item(DataClassItem()))
+        self.assertTrue(DataclassAdapter.is_item(DataClassItem(name="asdf", value=1234)))
+        # field metadata
+        self.assertEqual(
+            get_field_meta_from_class(DataClassItem, "name"), MappingProxyType({"serializer": str})
+        )
+        self.assertEqual(
+            get_field_meta_from_class(DataClassItem, "value"),
+            MappingProxyType({"serializer": int}),
+        )
+        with self.assertRaises(KeyError, msg="DataClassItem does not support field: non_existent"):
+            get_field_meta_from_class(DataClassItem, "non_existent")
+
+    def test_deprecated_is_instance(self):
+        from itemadapter.utils import is_dataclass_instance
+
+        with warnings.catch_warnings(record=True) as caught:
+            is_dataclass_instance(1)
+            self.assertEqual(len(caught), 1)
+            self.assertTrue(issubclass(caught[0].category, DeprecationWarning))
+            self.assertEqual(
+                "itemadapter.utils.is_dataclass_instance is deprecated"
+                " and it will be removed in a future version",
+                str(caught[0].message),
+            )