[Backport maintenance/3.0.x] [bugfix] Find files with ./ as input with a __init__.py file (#9286)

* [bugfix] Find files with ./ as input with a __init__.py file (#9211)

Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>
Co-authored-by: Daniël van Noord <13665637+DanielNoord@users.noreply.github.com>
(cherry picked from commit abdb874)

Author: 3 people

doc/whatsnew/fragments/9210.bugfix

@@ -0,0 +1,4 @@
+Fix a bug where pylint was unable to walk recursively through a directory if the
+directory has an `__init__.py` file.
+
+Closes #9210

pylint/lint/expand_modules.py

@@ -144,8 +144,9 @@ def expand_modules(
         )
         if has_init or is_namespace or is_directory:
             for subfilepath in modutils.get_module_files(
-                os.path.dirname(filepath), ignore_list, list_all=is_namespace
+                os.path.dirname(filepath) or ".", ignore_list, list_all=is_namespace
             ):
+                subfilepath = os.path.normpath(subfilepath)
                 if filepath == subfilepath:
                     continue
                 if _is_in_ignore_list_re(

tests/lint/unittest_expand_modules.py

@@ -4,7 +4,11 @@
 
 from __future__ import annotations
 
+import copy
+import os
 import re
+from collections.abc import Iterator
+from contextlib import contextmanager
 from pathlib import Path
 
 import pytest
@@ -28,7 +32,8 @@ def test__is_in_ignore_list_re_match() -> None:
 
 TEST_DIRECTORY = Path(__file__).parent.parent
 INIT_PATH = str(TEST_DIRECTORY / "lint/__init__.py")
-EXPAND_MODULES = str(TEST_DIRECTORY / "lint/unittest_expand_modules.py")
+EXPAND_MODULES_BASE = "unittest_expand_modules.py"
+EXPAND_MODULES = str(TEST_DIRECTORY / "lint" / EXPAND_MODULES_BASE)
 this_file = {
     "basename": "lint.unittest_expand_modules",
     "basepath": EXPAND_MODULES,
@@ -37,6 +42,14 @@ def test__is_in_ignore_list_re_match() -> None:
     "path": EXPAND_MODULES,
 }
 
+this_file_relative_to_parent = {
+    "basename": "lint.unittest_expand_modules",
+    "basepath": EXPAND_MODULES_BASE,
+    "isarg": True,
+    "name": "lint.unittest_expand_modules",
+    "path": EXPAND_MODULES_BASE,
+}
+
 this_file_from_init = {
     "basename": "lint",
     "basepath": INIT_PATH,
@@ -117,6 +130,27 @@ def _list_expected_package_modules(
     )
 
 
+def _list_expected_package_modules_relative() -> tuple[dict[str, object], ...]:
+    """Generates reusable list of modules for our package with relative path input."""
+    abs_result = copy.deepcopy(_list_expected_package_modules())
+    for item in abs_result:
+        assert isinstance(item["basepath"], str)
+        assert isinstance(item["path"], str)
+        item["basepath"] = os.path.relpath(item["basepath"], str(Path(__file__).parent))
+        item["path"] = os.path.relpath(item["path"], str(Path(__file__).parent))
+    return abs_result
+
+
+@contextmanager
+def pushd(path: Path) -> Iterator[None]:
+    prev = os.getcwd()
+    os.chdir(path)
+    try:
+        yield
+    finally:
+        os.chdir(prev)
+
+
 class TestExpandModules(CheckerTestCase):
     """Test the expand_modules function while allowing options to be set."""
 
@@ -159,6 +193,40 @@ def test_expand_modules(
         assert modules == expected
         assert not errors
 
+    @pytest.mark.parametrize(
+        "files_or_modules,expected",
+        [
+            (
+                [Path(__file__).name],
+                {this_file_relative_to_parent["path"]: this_file_relative_to_parent},
+            ),
+            (
+                ["./"],
+                {
+                    module["path"]: module  # pylint: disable=unsubscriptable-object
+                    for module in _list_expected_package_modules_relative()
+                },
+            ),
+        ],
+    )
+    @set_config(ignore_paths="")
+    def test_expand_modules_relative_path(
+        self, files_or_modules: list[str], expected: dict[str, ModuleDescriptionDict]
+    ) -> None:
+        """Test expand_modules with the default value of ignore-paths and relative path as input."""
+        ignore_list: list[str] = []
+        ignore_list_re: list[re.Pattern[str]] = []
+        with pushd(Path(__file__).parent):
+            modules, errors = expand_modules(
+                files_or_modules,
+                [],
+                ignore_list,
+                ignore_list_re,
+                self.linter.config.ignore_paths,
+            )
+            assert modules == expected
+            assert not errors
+
     @pytest.mark.parametrize(
         "files_or_modules,expected",
         [