typing: pytest_collection

1 files changed, 9 insertions, 1 deletions

diff --git a/src/_pytest/hookspec.py b/src/_pytest/hookspec.py
index 03e060eb8..2d9834c7f 100644
--- a/src/_pytest/hookspec.py
+++ b/src/_pytest/hookspec.py
@@ -1,6 +1,14 @@
 """ hook specifications for pytest plugins, invoked from main.py and builtin plugins.  """
+from typing import Any
+from typing import Optional
+
 from pluggy import HookspecMarker
 
+from _pytest.compat import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from _pytest.main import Session
+
 
 hookspec = HookspecMarker("pytest")
 
@@ -158,7 +166,7 @@ def pytest_load_initial_conftests(early_config, parser, args):
 
 
 @hookspec(firstresult=True)
-def pytest_collection(session):
+def pytest_collection(session: "Session") -> Optional[Any]:
     """Perform the collection protocol for the given session.
 
     Stops at first non-None result, see :ref:`firstresult`.