[refactor] PytestAsyncioFunction.substitute returns the specialized subclass rather than the instance.

Previously, PytestAsyncioFunction.substitute returned the Item instance unchanged, when no substitution occured. This change allows for different code branches based on whether the substitution happened or not.

Signed-off-by: Michael Seifert <m.seifert@digitalernachschub.de>

Author: seifertm

pytest_asyncio/plugin.py

@@ -21,6 +21,7 @@
     Literal,
     Optional,
     Set,
+    Type,
     TypeVar,
     Union,
     overload,
@@ -365,18 +366,19 @@ class PytestAsyncioFunction(Function):
     """Base class for all test functions managed by pytest-asyncio."""
 
     @classmethod
-    def substitute(cls, item: Function, /) -> Function:
+    def item_subclass_for(
+        cls, item: Function, /
+    ) -> Union[Type["PytestAsyncioFunction"], None]:
         """
-        Returns a PytestAsyncioFunction if there is an implementation that can handle
-        the specified function item.
+        Returns a subclass of PytestAsyncioFunction if there is a specialized subclass
+        for the specified function item.
 
-        If no implementation of PytestAsyncioFunction can handle the specified item,
-        the item is returned unchanged.
+        Return None if no specialized subclass exists for the specified item.
         """
         for subclass in cls.__subclasses__():
             if subclass._can_substitute(item):
-                return subclass._from_function(item)
-        return item
+                return subclass
+        return None
 
     @classmethod
     def _from_function(cls, function: Function, /) -> Function:
@@ -535,7 +537,9 @@ def pytest_pycollect_makeitem_convert_async_functions_to_subclass(
     for node in node_iterator:
         updated_item = node
         if isinstance(node, Function):
-            updated_item = PytestAsyncioFunction.substitute(node)
+            specialized_item_class = PytestAsyncioFunction.item_subclass_for(node)
+            if specialized_item_class:
+                updated_item = specialized_item_class._from_function(node)
         updated_node_collection.append(updated_item)
 
     hook_result.force_result(updated_node_collection)