From 7a25556ae56e0b8522f6990dce88df028069ba35 Mon Sep 17 00:00:00 2001
From: Bruno Oliveira <bruno@soliv.dev>
Date: Sun, 31 Mar 2024 09:35:48 -0300
Subject: [PATCH] Improve check for __init__ files

---
 src/_pytest/pathlib.py  | 11 +++++------
 testing/test_pathlib.py | 21 ++++++++++++++++++---
 2 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/src/_pytest/pathlib.py b/src/_pytest/pathlib.py
index 70479fe5a..27504230e 100644
--- a/src/_pytest/pathlib.py
+++ b/src/_pytest/pathlib.py
@@ -773,6 +773,11 @@ def resolve_pkg_root_and_module_name(
         pkg_root = pkg_path.parent
         if consider_namespace_packages:
             for candidate in (pkg_root, *pkg_root.parents):
+                # If any of the parent paths has an __init__.py, it means it is not a namespace package:
+                # https://packaging.python.org/en/latest/guides/packaging-namespace-packages
+                if (candidate / "__init__.py").is_file():
+                    break
+
                 if _is_namespace_package(candidate):
                     # Point the pkg_root to the root of the namespace package.
                     pkg_root = candidate.parent
@@ -788,12 +793,6 @@ def resolve_pkg_root_and_module_name(
 
 
 def _is_namespace_package(module_path: Path) -> bool:
-    # If the path has an __init__.py file, it means it is not
-    # a namespace package:
-    # https://packaging.python.org/en/latest/guides/packaging-namespace-packages
-    if (module_path / "__init__.py").is_file():
-        return False
-
     module_name = module_path.name
 
     # Empty module names break find_spec.
diff --git a/testing/test_pathlib.py b/testing/test_pathlib.py
index d123c18ff..8a162d9ad 100644
--- a/testing/test_pathlib.py
+++ b/testing/test_pathlib.py
@@ -1226,11 +1226,26 @@ class TestNamespacePackages:
         models_py, algorithms_py = self.setup_directories(
             tmp_path, monkeypatch, pytester
         )
-        # Namespace packages must not have an __init__.py at any of its
-        # directories; if it does, we then fall back to importing just the
-        # part of the package containing the __init__.py files.
+        # Namespace packages must not have an __init__.py at its top-level
+        # directory; if it does, it is no longer a namespace package and we fall back
+        # to importing just the part of the package containing the __init__.py files.
         (tmp_path / "src/dist1/com/__init__.py").touch()
 
+        # Ensure Python no longer considers dist1/com a namespace package.
+        r = pytester.runpython_c(
+            dedent(
+                f"""
+                import sys
+                sys.path.append(r{str(tmp_path / "src/dist1")!r})
+                sys.path.append(r{str(tmp_path / "src/dist2")!r})
+                import com.company.app.core.models
+                import com.company.calc.algo.algorithms
+                """
+            )
+        )
+        assert r.ret == 1
+        r.stderr.fnmatch_lines("*No module named 'com.company.calc*")
+
         pkg_root, module_name = resolve_pkg_root_and_module_name(
             models_py, consider_namespace_packages=True
         )