Fix build_meta when metadata_directory=='.' (#3528)

2 files changed, 30 insertions, 5 deletions

diff --git a/setuptools/build_meta.py b/setuptools/build_meta.py
index 98fb148a..8ff9a5ce 100644
--- a/setuptools/build_meta.py
+++ b/setuptools/build_meta.py
@@ -40,6 +40,7 @@ from typing import Dict, Iterator, List, Optional, Union
 
 import setuptools
 import distutils
+from . import errors
 from ._path import same_path
 from ._reqs import parse_strings
 from ._deprecation_warning import SetuptoolsDeprecationWarning
@@ -346,16 +347,23 @@ class _BuildMetaBackend(_ConfigSettingsTranslator):
 
         Returns the basename of the info directory, e.g. `proj-0.0.0.dist-info`.
         """
-        candidates = list(Path(metadata_directory).glob(f"**/*{suffix}/"))
-        assert len(candidates) == 1, f"Exactly one {suffix} should have been produced"
-        info_dir = candidates[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):
         sys.argv = [
diff --git a/setuptools/tests/test_build_meta.py b/setuptools/tests/test_build_meta.py
index e70c71bd..bf1c27ff 100644
--- a/setuptools/tests/test_build_meta.py
+++ b/setuptools/tests/test_build_meta.py
@@ -485,6 +485,23 @@ class TestBuildMetaBackend:
 
         assert os.path.isfile(os.path.join(dist_dir, dist_info, 'METADATA'))
 
+    def test_prepare_metadata_inplace(self, build_backend):
+        """
+        Some users might pass metadata_directory pre-populated with `.tox` or `.venv`.
+        See issue #3523.
+        """
+        for pre_existing in [
+            ".tox/python/lib/python3.10/site-packages/attrs-22.1.0.dist-info",
+            ".tox/python/lib/python3.10/site-packages/autocommand-2.2.1.dist-info",
+            ".nox/python/lib/python3.10/site-packages/build-0.8.0.dist-info",
+            ".venv/python3.10/site-packages/click-8.1.3.dist-info",
+            "venv/python3.10/site-packages/distlib-0.3.5.dist-info",
+            "env/python3.10/site-packages/docutils-0.19.dist-info",
+        ]:
+            os.makedirs(pre_existing, exist_ok=True)
+        dist_info = build_backend.prepare_metadata_for_build_wheel(".")
+        assert os.path.isfile(os.path.join(dist_info, 'METADATA'))
+
     def test_build_sdist_explicit_dist(self, build_backend):
         # explicitly specifying the dist folder should work
         # the folder sdist_directory and the ``--dist-dir`` can be the same