Add a docstring to get_related_files

Author: Pierre-Sassoulas

pylint/testutils/configuration_test.py

@@ -68,21 +68,22 @@ def get_expected_configuration(
     return result
 
 
+def get_related_files(
+    tested_configuration_file: Union[str, Path], suffix_filter: str
+) -> List[Path]:
+    """Return all the file related to a test conf file endind with a suffix."""
+    conf_path = Path(tested_configuration_file)
+    return [
+        p
+        for p in conf_path.parent.iterdir()
+        if str(p.stem).startswith(conf_path.stem) and str(p).endswith(suffix_filter)
+    ]
+
+
 def get_expected_output(
     configuration_path: Union[str, Path], user_specific_path: Path
 ) -> Tuple[int, str]:
     """Get the expected output of a functional test."""
-
-    def get_related_files(
-        tested_configuration_file: Union[str, Path], suffix_filter: str
-    ) -> List[Path]:
-        conf_path = Path(tested_configuration_file)
-        return [
-            p
-            for p in conf_path.parent.iterdir()
-            if str(p.stem).startswith(conf_path.stem) and str(p).endswith(suffix_filter)
-        ]
-
     exit_code = 0
     msg = (
         "we expect a single file of the form "