fix: Prevent crash on file in PATH during discovery (#2917)

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: 3 people

src/virtualenv/discovery/builtin.py

@@ -186,7 +186,7 @@ def get_paths(env: Mapping[str, str]) -> Generator[Path, None, None]:
     if path:
         for p in map(Path, path.split(os.pathsep)):
             with suppress(OSError):
-                if next(p.iterdir(), None):
+                if p.is_dir() and next(p.iterdir(), None):
                     yield p
 
 
@@ -202,7 +202,13 @@ def __repr__(self) -> str:
             content += " with =>"
             for file_path in self.path.iterdir():
                 try:
-                    if file_path.is_dir() or not (file_path.stat().st_mode & os.X_OK):
+                    if file_path.is_dir():
+                        continue
+                    if IS_WIN:
+                        pathext = self.env.get("PATHEXT", ".COM;.EXE;.BAT;.CMD").split(";")
+                        if not any(file_path.name.upper().endswith(ext) for ext in pathext):
+                            continue
+                    elif not (file_path.stat().st_mode & os.X_OK):
                         continue
                 except OSError:
                     pass

tests/unit/discovery/test_discovery.py

@@ -11,9 +11,9 @@
 
 import pytest
 
-from virtualenv.discovery.builtin import Builtin, get_interpreter
+from virtualenv.discovery.builtin import Builtin, LazyPathDump, get_interpreter, get_paths
 from virtualenv.discovery.py_info import PythonInfo
-from virtualenv.info import fs_supports_symlink
+from virtualenv.info import IS_WIN, fs_supports_symlink
 
 
 @pytest.mark.skipif(not fs_supports_symlink(), reason="symlink not supported")
@@ -200,6 +200,14 @@ def test_returns_second_python_specified_when_more_than_one_is_specified_and_env
     assert result == mocker.sentinel.python_from_cli
 
 
+def test_discovery_via_path_with_file(tmp_path, monkeypatch):
+    a_file = tmp_path / "a_file"
+    a_file.touch()
+    monkeypatch.setenv("PATH", str(a_file))
+    interpreter = get_interpreter(uuid4().hex, [])
+    assert interpreter is None
+
+
 def test_absolute_path_does_not_exist(tmp_path):
     """
     Test that virtualenv does not fail when an absolute path that does not exist is provided.
@@ -255,6 +263,24 @@ def test_absolute_path_does_not_exist_fails(tmp_path):
     assert process.returncode != 0, process.stderr
 
 
+def test_get_paths_no_path_env(monkeypatch):
+    monkeypatch.delenv("PATH", raising=False)
+    paths = list(get_paths({}))
+    assert paths
+
+
+def test_lazy_path_dump_debug(monkeypatch, tmp_path):
+    monkeypatch.setenv("_VIRTUALENV_DEBUG", "1")
+    a_dir = tmp_path
+    executable_file = "a_file.exe" if IS_WIN else "a_file"
+    (a_dir / executable_file).touch(mode=0o755)
+    (a_dir / "b_file").touch(mode=0o644)
+    dumper = LazyPathDump(0, a_dir, os.environ)
+    output = repr(dumper)
+    assert executable_file in output
+    assert "b_file" not in output
+
+
 @pytest.mark.usefixtures("mock_get_interpreter")
 def test_returns_first_python_specified_when_no_env_var_is_specified(mocker, monkeypatch, session_app_data):
     monkeypatch.delenv("VIRTUALENV_PYTHON", raising=False)