fix py.typed discovery for mutli-package projects

src/typestats/index.py

@@ -1,5 +1,4 @@
 import enum
-import os
 from typing import Final
 
 import anyio
@@ -39,14 +38,25 @@ def sort_key(self) -> int:
 EXCLUDED_FILE_NAMES: Final[frozenset[str]] = frozenset({"conftest.py", "setup.py"})
 
 
-async def get_py_typed(sources: StrPaths, /) -> PyTyped:
-    """Determine the `py.typed` status from a list of source paths."""
-    assert sources
+async def _is_package_dir(path: anyio.Path, /) -> bool:
+    """Whether *path* is an importable regular package (has an `__init__`)."""
+    return (
+        await (path / "__init__.py").exists() or await (path / "__init__.pyi").exists()
+    )
+
 
-    root = anyio.Path(os.path.commonpath(sources))
+async def _package_root(source: str, /) -> anyio.Path:
+    """Top-level package dir of *source*, e.g. `_pytest/_code/x.py` -> `_pytest`."""
+    root = anyio.Path(source)
     if await root.is_file():
         root = root.parent
+    while await _is_package_dir(root.parent):
+        root = root.parent
+    return root
+
 
+async def _py_typed_for_root(root: anyio.Path, /) -> PyTyped:
+    """Determine the `py.typed` status of a single top-level package directory."""
     py_typed = root / "py.typed"
     if not await py_typed.exists():
         # PEP 561: stub-only packages use *-stubs directory naming.
@@ -57,3 +67,17 @@ async def get_py_typed(sources: StrPaths, /) -> PyTyped:
         return PyTyped.PARTIAL
 
     return PyTyped.YES
+
+
+async def get_py_typed(sources: StrPaths, /) -> PyTyped:
+    """Determine the `py.typed` status from a list of source paths.
+
+    A distribution may ship several top-level packages (e.g. `pytest` ships both
+    `pytest` and `_pytest`); each is inspected independently and the most-typed
+    status wins, so an untyped private package can't mask a typed public one.
+    """
+    assert sources
+
+    roots = {str(await _package_root(str(s))) for s in sources}
+    statuses = [await _py_typed_for_root(anyio.Path(r)) for r in roots]
+    return min(statuses, key=PyTyped.sort_key)

tests/test_index.py

@@ -34,3 +34,42 @@ async def test_partial(self, tmp_path: Path) -> None:
         (pkg / "__init__.py").write_text("")
         (pkg / "py.typed").write_text("partial\n")
         assert await get_py_typed([pkg / "__init__.py"]) == PyTyped.PARTIAL
+
+    async def test_nested_module_resolves_to_top_level(self, tmp_path: Path) -> None:
+        pkg = tmp_path / "mypkg"
+        sub = pkg / "sub"
+        sub.mkdir(parents=True)
+        (pkg / "__init__.py").write_text("")
+        (pkg / "py.typed").write_text("")
+        (sub / "__init__.py").write_text("")
+        (sub / "mod.py").write_text("")
+        assert await get_py_typed([sub / "mod.py"]) == PyTyped.YES
+
+    async def test_multiple_top_level_packages(self, tmp_path: Path) -> None:
+        # gh-415: pytest ships both `pytest` and `_pytest`, each with py.typed.
+        for name in ("pkg", "_pkg"):
+            pkg = tmp_path / name
+            pkg.mkdir()
+            (pkg / "__init__.py").write_text("")
+            (pkg / "py.typed").write_text("")
+        sources = [
+            tmp_path / "pkg" / "__init__.py",
+            tmp_path / "_pkg" / "__init__.py",
+        ]
+        assert await get_py_typed(sources) == PyTyped.YES
+
+    async def test_private_package_without_marker_does_not_mask(
+        self, tmp_path: Path
+    ) -> None:
+        typed = tmp_path / "pkg"
+        typed.mkdir()
+        (typed / "__init__.py").write_text("")
+        (typed / "py.typed").write_text("")
+        private = tmp_path / "_pkg"
+        private.mkdir()
+        (private / "__init__.py").write_text("")
+        sources = [
+            typed / "__init__.py",
+            private / "__init__.py",
+        ]
+        assert await get_py_typed(sources) == PyTyped.YES