Update Python ProjectScanner

docs/user/features/type-parameter-modernization.md

@@ -421,7 +421,8 @@ python src/rejuvenation/migration_type_recipes.py <path> --py MAJOR.MINOR \
     [--report PATH] [--no-ruff] [--ignore FILE...] [--no-localization] [--second-pass]
 ```
 
-- `<path>`: a `.py` file or a directory, scanned recursively except `.git`, `__pycache__`, `.pixi`, `.venv` and `venv`.
+- `<path>`: a `.py` file or a directory, scanned recursively for `.py` files. Files and directories starting with `.`,
+  and `__pycache__` and `venv` directories, are skipped.
 - `--py` (required): the oldest Python version the target project supports, 3.12 or higher.
 - `--report`: also write the report to a file.
 - `--no-ruff`: skip the final `ruff` pass.

src/renaissance/project/project_scanner.py

@@ -53,10 +53,9 @@ def find_sources(self) -> list[str]:
 
 
 class PythonScanner(ProjectScanner):
-    """Scan a directory tree for Python source files."""
+    """Scan a directory tree for Python source files, skipping hidden files and directories."""
 
-    EXCLUDED_DIRS = frozenset({".git", "__pycache__", ".venv", "venv"})
-    # TODO: incomplete list, extend this list with more files/directories that should always be ignored
+    SPECIAL_EXCLUDED_DIRS = frozenset({"__pycache__", "venv"})
 
     def __init__(self, root_dir: str = ".", package_dirs: list[str] | None = None) -> None:
         """Store the scan root and optional package_dirs narrowing.
@@ -69,7 +68,11 @@ def __init__(self, root_dir: str = ".", package_dirs: list[str] | None = None) -
         self.package_dirs = package_dirs
 
     def find_sources(self) -> list[str]:
-        """Return every .py file under root_dir (or package_dirs, if given), sorted, excluding EXCLUDED_DIRS."""
+        """Return every .py file under root_dir (or package_dirs, if given), sorted.
+
+        Files and directories whose name starts with "." are skipped, as are EXCLUDED_DIRS subdirectories.
+        The names of root_dir and package_dirs themselves are never checked.
+        """
         path = Path(self.root_dir)
         if not path.exists():
             message = f"root_dir does not exist: {self.root_dir}"
@@ -78,13 +81,16 @@ def find_sources(self) -> list[str]:
             message = f"root_dir is not a directory: {self.root_dir}"
             raise NotADirectoryError(message)
 
-        roots = [Path(self.root_dir) / d for d in self.package_dirs] if self.package_dirs else [Path(self.root_dir)]
+        roots = [path / d for d in self.package_dirs] if self.package_dirs else [path]
         files: list[Path] = []
         for root in roots:
             if not root.exists():
                 continue
-            files.extend(path for path in root.rglob("*.py") if not any(part in self.EXCLUDED_DIRS for part in path.parts))
-        return sorted(str(path) for path in files)
+            for dirpath, dirnames, filenames in root.walk():
+                # Pruning in place stops walk() from descending into skipped directories at all.
+                dirnames[:] = [name for name in dirnames if not name.startswith(".") and name not in self.SPECIAL_EXCLUDED_DIRS]
+                files.extend(dirpath / name for name in filenames if name.endswith(".py") and not name.startswith("."))
+        return sorted(str(file) for file in files)
 
 
 class BearCppScanner(CppScanner):

test/project/test_project_scanner.py

@@ -22,6 +22,8 @@
     PythonScanner,
 )
 
+NOISE_DIR_NAMES = sorted({*PythonScanner.SPECIAL_EXCLUDED_DIRS, ".git", ".venv", ".pixi", ".tox"})
+
 # ---------------------------------------------------------------------------
 # ProjectScanner (base)
 # ---------------------------------------------------------------------------
@@ -228,7 +230,7 @@ def test_raises_when_root_dir_is_not_a_directory(self, tmp_path) -> None:
 
         assert_that(calling(scanner.find_sources), raises(NotADirectoryError))
 
-    @pytest.mark.parametrize("excluded_dir", sorted(PythonScanner.EXCLUDED_DIRS))
+    @pytest.mark.parametrize("excluded_dir", NOISE_DIR_NAMES)
     def test_excludes_known_noise_dirs_in_default_whole_tree_scan(self, tmp_path, excluded_dir) -> None:
         """Assert PythonScanner.find_sources excludes known noise directories during a default whole-tree scan."""
         noise_dir = tmp_path / excluded_dir
@@ -241,7 +243,7 @@ def test_excludes_known_noise_dirs_in_default_whole_tree_scan(self, tmp_path, ex
 
         assert_that(result, equal_to(["kept.py"]))
 
-    @pytest.mark.parametrize("excluded_dir", sorted(PythonScanner.EXCLUDED_DIRS))
+    @pytest.mark.parametrize("excluded_dir", NOISE_DIR_NAMES)
     def test_excludes_known_noise_dirs_within_explicit_package_dirs(self, tmp_path, excluded_dir) -> None:
         """Assert PythonScanner.find_sources excludes known noise directories within an explicit package_dirs."""
         src = tmp_path / "src"
@@ -268,6 +270,31 @@ def test_default_package_dirs_scans_whole_root_dir(self, tmp_path) -> None:
 
         assert_that(result, equal_to([str(redis_like / "client.py")]))
 
+    @pytest.mark.parametrize("excluded_dir", NOISE_DIR_NAMES)
+    def test_root_dir_inside_excluded_name_is_still_scanned(self, tmp_path: Path, excluded_dir: str) -> None:
+        """Assert PythonScanner.find_sources only skips excluded names below root_dir, never in its ancestors."""
+        root = tmp_path / excluded_dir / "project"
+        noise_dir = root / excluded_dir
+        noise_dir.mkdir(parents=True)
+        (noise_dir / "ignored.py").write_text("")
+        (root / "kept.py").write_text("")
+
+        scanner = PythonScanner(str(root))
+        result = [Path(p).name for p in scanner.find_sources()]
+
+        assert_that(result, equal_to(["kept.py"]))
+
+    @pytest.mark.parametrize("hidden_name", [".hidden.py", ".py"])
+    def test_skips_files_starting_with_a_dot(self, tmp_path: Path, hidden_name: str) -> None:
+        """Assert PythonScanner.find_sources skips Python files whose name starts with a dot."""
+        (tmp_path / hidden_name).write_text("")
+        (tmp_path / "kept.py").write_text("")
+
+        scanner = PythonScanner(str(tmp_path))
+        result = [Path(p).name for p in scanner.find_sources()]
+
+        assert_that(result, equal_to(["kept.py"]))
+
 
 # ---------------------------------------------------------------------------
 # BearCppScanner