From 36a3191014d0c40b1291301a795f6c37ba4d8363 Mon Sep 17 00:00:00 2001
From: Casey Brooks <casey.brooks@agyn.io>
Date: Thu, 25 Dec 2025 20:50:22 +0000
Subject: [PATCH] fix(python): guard package init imports

---
 src/_pytest/python.py      | 29 +++++++++++++--------
 testing/python/collect.py  | 52 ++++++++++++++++++++++++++++++++++++++
 testing/test_collection.py |  4 +--
 3 files changed, 73 insertions(+), 12 deletions(-)

diff --git a/src/_pytest/python.py b/src/_pytest/python.py
index 306e5f217ce..88aec1a7ca3 100644
--- a/src/_pytest/python.py
+++ b/src/_pytest/python.py
@@ -568,19 +568,23 @@ def __init__(self, fspath, parent=None, config=None, session=None, nodeid=None):
         self.fspath = fspath
 
     def setup(self):
+        if not self._should_import_init():
+            return
+
         # not using fixtures to call setup_module here because autouse fixtures
         # from packages are not called automatically (#4085)
+        package_obj = self.obj
         setup_module = _get_first_non_fixture_func(
-            self.obj, ("setUpModule", "setup_module")
+            package_obj, ("setUpModule", "setup_module")
         )
         if setup_module is not None:
-            _call_with_optional_argument(setup_module, self.obj)
+            _call_with_optional_argument(setup_module, package_obj)
 
         teardown_module = _get_first_non_fixture_func(
-            self.obj, ("tearDownModule", "teardown_module")
+            package_obj, ("tearDownModule", "teardown_module")
         )
         if teardown_module is not None:
-            func = partial(_call_with_optional_argument, teardown_module, self.obj)
+            func = partial(_call_with_optional_argument, teardown_module, package_obj)
             self.addfinalizer(func)
 
     def _recurse(self, dirpath):
@@ -639,13 +643,9 @@ def isinitpath(self, path):
         return path in self.session._initialpaths
 
     def collect(self):
-        self._mount_obj_if_needed()
         this_path = self.fspath.dirpath()
-        init_module = this_path.join("__init__.py")
-        if init_module.check(file=1) and path_matches_patterns(
-            init_module, self.config.getini("python_files")
-        ):
-            yield Module(init_module, self)
+        if self._should_import_init():
+            yield Module(self.fspath, self)
         pkg_prefixes = set()
         for path in this_path.visit(rec=self._recurse, bf=True, sort=True):
             # We will visit our own __init__.py file, in which case we skip it.
@@ -669,6 +669,15 @@ def collect(self):
             elif path.join("__init__.py").check(file=1):
                 pkg_prefixes.add(path)
 
+    def _should_import_init(self):
+        init_module = self.fspath
+        if not init_module.check(file=1):
+            return False
+        if self.isinitpath(init_module):
+            return True
+        python_files = self.config.getini("python_files")
+        return path_matches_patterns(init_module, python_files)
+
 
 def _call_with_optional_argument(func, arg):
     """Call the given function with the given argument if func accepts one argument, otherwise
diff --git a/testing/python/collect.py b/testing/python/collect.py
index f0c12df1672..80cbecb1cc7 100644
--- a/testing/python/collect.py
+++ b/testing/python/collect.py
@@ -1336,3 +1336,55 @@ def test_package_ordering(testdir):
     # Execute from .
     result = testdir.runpytest("-v", "-s")
     result.assert_outcomes(passed=3)
+
+
+def test_package_init_not_imported_when_not_a_test_module(testdir):
+    testdir.makepyfile(
+        **{
+            "pkg/__init__.py": 'assert False, "should not be imported"\n',
+            "tests/test_mod.py": "def test_ok():\n    pass\n",
+        }
+    )
+
+    result = testdir.runpytest()
+    result.assert_outcomes(passed=1)
+    assert "should not be imported" not in result.stdout.str()
+
+
+def test_package_init_collected_when_enabled_via_python_files(testdir):
+    testdir.makeini(
+        """
+        [pytest]
+        python_files = *.py
+    """
+    )
+    testdir.makepyfile(
+        **{
+            "pkg/__init__.py": "def test_from_init():\n    assert True\n",
+        }
+    )
+
+    result = testdir.runpytest("-k", "test_from_init")
+    result.assert_outcomes(passed=1)
+
+
+def test_src_layout_package_init_not_imported(testdir):
+    testdir.makepyfile(
+        **{
+            "src/pkg/__init__.py": 'assert False, "should not be imported"\n',
+            "tests/test_ok.py": "def test_ok():\n    pass\n",
+        }
+    )
+
+    result = testdir.runpytest()
+    result.assert_outcomes(passed=1)
+    assert "should not be imported" not in result.stdout.str()
+
+
+def test_namespace_package_without_init_collects_normally(testdir):
+    testdir.makepyfile(
+        **{"ns_pkg/test_mod.py": "def test_namespace():\n    pass\n"}
+    )
+
+    result = testdir.runpytest()
+    result.assert_outcomes(passed=1)
diff --git a/testing/test_collection.py b/testing/test_collection.py
index dee07d5c715..fe533556069 100644
--- a/testing/test_collection.py
+++ b/testing/test_collection.py
@@ -1187,7 +1187,7 @@ def test_collect_pkg_init_and_file_in_args(testdir):
     result = testdir.runpytest("-v", str(init), str(p))
     result.stdout.fnmatch_lines(
         [
-            "sub/test_file.py::test_file PASSED*",
+            "sub/__init__.py::test_init PASSED*",
             "sub/test_file.py::test_file PASSED*",
             "*2 passed in*",
         ]
@@ -1209,7 +1209,7 @@ def test_collect_pkg_init_only(testdir):
     init.write("def test_init(): pass")
 
     result = testdir.runpytest(str(init))
-    result.stdout.fnmatch_lines(["*no tests ran in*"])
+    result.stdout.fnmatch_lines(["*1 passed in*"])
 
     result = testdir.runpytest("-v", "-o", "python_files=*.py", str(init))
     result.stdout.fnmatch_lines(["sub/__init__.py::test_init PASSED*", "*1 passed in*"])