Fix publicity of module in private package

src/pydocstyle/parser.py

@@ -119,7 +119,16 @@ def is_public(self):
         This helps determine if it requires a docstring.
         """
         module_name = Path(self.name).name
-        return not module_name.startswith('_') or module_name.startswith('__')
+        return (
+            not self._is_inside_private_package() and
+            (not module_name.startswith('_') or module_name.startswith('__'))
+        )
+
+    def _is_inside_private_package(self):
+        """Return True if the module is inside a private package."""
+        path = Path(self.name)
+        package_names = path.parts[:-1]
+        return any([package.startswith('_') for package in package_names])
 
     def __str__(self):
         return 'at module level'

src/tests/parser_test.py

@@ -575,6 +575,13 @@ def test_module_publicity(parent_path):
     module = parser.parse(code, str(parent_path / "filepath"))
     assert module.is_public
 
+    module = parser.parse(code, str(parent_path / "_private_pkg" / "filepath"))
+    assert not module.is_public
+
+    module = parser.parse(code, str(
+        parent_path / "_private_pkg" / "some_pkg" / "filepath"))
+    assert not module.is_public
+
     module = parser.parse(code, str(parent_path / "_filepath"))
     assert not module.is_public