_discovery.py: 4 robustness issues with namespace pkgs, hidden dirs, broken submodules, false positive __init__ match

[pramodavansaber]

Hi maldoinc — found four edge-case crashes in wireup/_discovery.py while running adversarial test generation against the repo via tailtest. All four make _find_objects_in_module crash on legitimate Python project layouts; all four have small fixes.

1. module.__file__ AttributeError on PEP 420 namespace packages

Line 62: module.__file__ is accessed unconditionally. PEP 420 namespace packages don't have __file__ and crash with AttributeError.

Fix: getattr(module, '__file__', None)

2. endswith("__init__.py") false positives

Line 63: f.endswith("__init__.py") matches not__init__.py, treating it as a package and scanning its parent directory.

Fix: Path(f).name == "__init__.py"

3. Hidden directories traversed

Line 47: only __pycache__ is filtered. Dirs like .git, .mypy_cache, .pytest_cache, .hidden are traversed and importlib.import_module is called with invalid dot-prefixed names → ModuleNotFoundError.

Fix: also skip entry.name.startswith(".")

4. One broken submodule crashes entire discovery

Line 59: importlib.import_module is not wrapped in try/except. A single sub-module with an import error (e.g., missing optional dep) kills the whole discovery scan.

Fix: wrap in try/except (ImportError, Exception) and skip-with-warning instead of crashing.

Reproduction

Failing pytest cases for all four are below — drop into tests/test_discovery.py. Each test is ~10-15 LoC, fully isolated.

import os
import sys
import tempfile
import types
import pytest
from wireup._discovery import _find_objects_in_module


# Bug 1: namespace packages crash
def test_namespace_package_module_without_file_attr():
    """PEP 420 namespace packages have no __file__; should be handled."""
    mod = types.ModuleType("ns_pkg")
    if hasattr(mod, "__file__"):
        del mod.__file__
    # Should not raise AttributeError
    list(_find_objects_in_module(mod, predicate=lambda _: False))


# Bug 2: false-positive endswith("__init__.py")
def test_file_named_like_init_but_not_init(tmp_path):
    """File named not__init__.py should NOT be treated as a package."""
    pkg = tmp_path / "my_pkg"
    pkg.mkdir()
    (pkg / "not__init__.py").write_text("X = 1\n")
    sys.path.insert(0, str(tmp_path))
    try:
        import importlib
        mod = importlib.import_module("my_pkg.not__init__")
        list(_find_objects_in_module(mod, predicate=lambda _: False))
    finally:
        sys.path.remove(str(tmp_path))


# Bug 3: hidden dirs traversed
def test_dotdir_in_package_causes_import_attempt(tmp_path):
    """Dirs starting with '.' should be skipped during discovery."""
    pkg = tmp_path / "hidden_pkg"
    pkg.mkdir()
    (pkg / "__init__.py").write_text("")
    (pkg / ".hidden").mkdir()
    (pkg / ".hidden" / "__init__.py").write_text("")
    sys.path.insert(0, str(tmp_path))
    try:
        import importlib
        mod = importlib.import_module("hidden_pkg")
        # Should not raise ModuleNotFoundError on hidden_pkg..hidden
        list(_find_objects_in_module(mod, predicate=lambda _: False))
    finally:
        sys.path.remove(str(tmp_path))


# Bug 4: broken submodule crashes discovery
def test_broken_submodule_crashes_discovery(tmp_path):
    """One sub-module with an ImportError should not kill all discovery."""
    pkg = tmp_path / "brokenpkg"
    pkg.mkdir()
    (pkg / "__init__.py").write_text("")
    (pkg / "good.py").write_text("class A: ...")
    (pkg / "bad.py").write_text("import nonexistent_dep")
    sys.path.insert(0, str(tmp_path))
    try:
        import importlib
        mod = importlib.import_module("brokenpkg")
        # Should not raise; should return objects from good.py
        result = list(_find_objects_in_module(mod, predicate=lambda _: True))
    finally:
        sys.path.remove(str(tmp_path))

Happy to open a PR if useful — the changes are small enough to be a single commit. Found via tailtest's adversarial test generation.

[maldoinc]

Hi, @pramodavansaber thanks for this! Feel free to create one issue or pr for each item so we can discuss these independently.