From a8456a8b5d4fdbfdc8ec478d7814629e9a932814 Mon Sep 17 00:00:00 2001
From: Sashko <20253875+sashko1988@users.noreply.github.com>
Date: Thu, 29 May 2025 15:21:52 +0200
Subject: [PATCH] Improve `nodes._check_initialpaths_for_relpath` performance
 (#13448)

Use `Path` facilities to greatly improve performance of `nodes._check_initialpaths_for_relpath` (see #13448 for performance comparison).

Related: #13420, #13413.

---------

Co-authored-by: Bruno Oliveira <bruno@soliv.dev>
(cherry picked from commit bd6877e5874b50ee57d0f63b342a67298ee9a1c3)
---
 AUTHORS                         |  1 +
 changelog/13420.improvement.rst |  1 +
 src/_pytest/nodes.py            | 12 +++++++-----
 3 files changed, 9 insertions(+), 5 deletions(-)
 create mode 100644 changelog/13420.improvement.rst

diff --git a/AUTHORS b/AUTHORS
index 2cf48dd00f9..0a94dba871d 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -319,6 +319,7 @@ Nikolay Kondratyev
 Nipunn Koorapati
 Oleg Pidsadnyi
 Oleg Sushchenko
+Oleksandr Zavertniev
 Olga Matoula
 Oliver Bestwalter
 Omar Kohl
diff --git a/changelog/13420.improvement.rst b/changelog/13420.improvement.rst
new file mode 100644
index 00000000000..54fe50a72b0
--- /dev/null
+++ b/changelog/13420.improvement.rst
@@ -0,0 +1 @@
+Improved test collection performance by optimizing path resolution used in ``FSCollector``.
diff --git a/src/_pytest/nodes.py b/src/_pytest/nodes.py
index 2b818ade252..33aaae9e81d 100644
--- a/src/_pytest/nodes.py
+++ b/src/_pytest/nodes.py
@@ -38,7 +38,6 @@
 from _pytest.mark.structures import NodeKeywords
 from _pytest.outcomes import fail
 from _pytest.pathlib import absolutepath
-from _pytest.pathlib import commonpath
 from _pytest.stash import Stash
 from _pytest.warning_types import PytestWarning
 
@@ -548,10 +547,13 @@ def _traceback_filter(self, excinfo: ExceptionInfo[BaseException]) -> Traceback:
 def _check_initialpaths_for_relpath(
     initial_paths: frozenset[Path], path: Path
 ) -> str | None:
-    for initial_path in initial_paths:
-        if commonpath(path, initial_path) == initial_path:
-            rel = str(path.relative_to(initial_path))
-            return "" if rel == "." else rel
+    if path in initial_paths:
+        return ""
+
+    for parent in path.parents:
+        if parent in initial_paths:
+            return str(path.relative_to(parent))
+
     return None