Refactor code to bubble up info directories in build_meta

1 files changed, 18 insertions, 25 deletions

diff --git a/setuptools/build_meta.py b/setuptools/build_meta.py
index 3a256259..ad5b904b 100644
--- a/setuptools/build_meta.py
+++ b/setuptools/build_meta.py
@@ -36,10 +36,11 @@ import contextlib
 import tempfile
 import warnings
 from pathlib import Path
-from typing import Dict, Iterator, List, Optional, Union
+from typing import Dict, Iterator, List, Optional, Union, Tuple
 
 import setuptools
 import distutils
+from . import errors
 from ._path import same_path
 from ._reqs import parse_strings
 from ._deprecation_warning import SetuptoolsDeprecationWarning
@@ -346,30 +347,22 @@ class _BuildMetaBackend(_ConfigSettingsTranslator):
 
         Returns the basename of the info directory, e.g. `proj-0.0.0.dist-info`.
         """
-        dist_info_directory = metadata_directory
-        while True:
-            dist_infos = [f for f in os.listdir(dist_info_directory)
-                          if f.endswith('.dist-info')]
-
-            if (
-                len(dist_infos) == 0 and
-                len(_get_immediate_subdirectories(dist_info_directory)) == 1
-            ):
-
-                dist_info_directory = os.path.join(
-                    dist_info_directory, os.listdir(dist_info_directory)[0])
-                continue
-
-            assert len(dist_infos) == 1
-            break
-
-        if dist_info_directory != metadata_directory:
-            shutil.move(
-                os.path.join(dist_info_directory, dist_infos[0]),
-                metadata_directory)
-            shutil.rmtree(dist_info_directory, ignore_errors=True)
-
-        return dist_infos[0]
+        info_dir = self._find_info_directory(metadata_directory, suffix)
+        if not same_path(info_dir.parent, metadata_directory):
+            shutil.move(str(info_dir), metadata_directory)
+            # PEP 517 allow other files and dirs to exist in metadata_directory
+        return info_dir.name
+
+    def _find_info_directory(self, metadata_directory: str, suffix: str) -> Path:
+        for parent, dirs, _ in os.walk(metadata_directory):
+            candidates = [f for f in dirs if f.endswith(suffix)]
+
+            if len(candidates) != 0 or len(dirs) != 1:
+                assert len(candidates) == 1, f"Multiple {suffix} directories found"
+                return Path(parent, candidates[0])
+
+        msg = f"No {suffix} directory found in {metadata_directory}"
+        raise errors.InternalError(msg)
 
     def prepare_metadata_for_build_wheel(self, metadata_directory,
                                          config_settings=None):