Refactor pytests to make pickle testing in-memory

tests/conftest.py

@@ -6,7 +6,7 @@
 from importlib import import_module
 from sys import version_info as _version_info
 from types import ModuleType
-from typing import Callable, Type
+from typing import Any, Callable, Type
 
 try:
     from functools import cached_property  # Python 3.8+
@@ -158,6 +158,28 @@ def multidict_getversion_callable(multidict_module: ModuleType) -> Callable:
     return multidict_module.getversion
 
 
+def write(cls: Any, proto: int) -> bytes:
+    d = cls([("a", 1), ("a", 2)])
+    return pickle.dumps(d, proto)
+
+
+@pytest.fixture
+def in_memory_pickle_classes(multidict_module: ModuleType) -> dict[str, bytes]:
+    """Generates a dict for in-memory storage of pickled classes"""
+    pickle_dict = {}
+    _impl_map = {
+        "c-extension": "_multidict",
+        "pure-python": "_multidict_py",
+    }
+    for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+        for tag, impl_name in _impl_map.items():
+            impl = import_module(f"multidict.{impl_name}")
+            for cls in impl.CIMultiDict, impl.MultiDict:
+                file_key = f"{cls.__name__.lower()}-{tag}.pickle.{proto}"
+                pickle_dict[file_key] = write(cls, proto)
+    return pickle_dict
+
+
 def pytest_addoption(
     parser: pytest.Parser,
     pluginmanager: pytest.PytestPluginManager,

tests/test_pickle.py

@@ -21,7 +21,12 @@ def test_pickle_proxy(any_multidict_class, any_multidict_proxy_class):
         pickle.dumps(proxy)
 
 
-def test_load_from_file(any_multidict_class, multidict_implementation, pickle_protocol):
+def test_load_from_file(
+    any_multidict_class,
+    multidict_implementation,
+    in_memory_pickle_classes,
+    pickle_protocol,
+):
     multidict_class_name = any_multidict_class.__name__
     pickle_file_basename = "-".join(
         (
@@ -31,8 +36,6 @@ def test_load_from_file(any_multidict_class, multidict_implementation, pickle_pr
     )
     d = any_multidict_class([("a", 1), ("a", 2)])
     fname = f"{pickle_file_basename}.pickle.{pickle_protocol}"
-    p = here / fname
-    with p.open("rb") as f:
-        obj = pickle.load(f)
+    obj = pickle.loads(in_memory_pickle_classes[fname])
     assert d == obj
     assert isinstance(obj, any_multidict_class)