Fix i18n _get_default_locale_path

Fixes python-humanize#105

Use importlib.resources available since Python 3.9 to find the location
of the locale folder containing the translations.

src/humanize/i18n.py

@@ -3,7 +3,9 @@
 from __future__ import annotations
 
 import gettext as gettext_module
-import os.path
+import importlib.resources
+import os
+import pathlib
 from threading import local
 
 __all__ = ["activate", "deactivate", "decimal_separator", "thousands_separator"]
@@ -32,14 +34,13 @@
 }
 
 
-def _get_default_locale_path() -> str | None:
-    try:
-        if __file__ is None:
-            return None
-        return os.path.join(os.path.dirname(__file__), "locale")
-    except NameError:
+def _get_default_locale_path() -> pathlib.Path | None:
+    if __package__ == "":
         return None
 
+    with importlib.resources.as_file(importlib.resources.files(__package__)) as pkg:
+        return pkg / "locale"
+
 
 def get_translation() -> gettext_module.NullTranslations:
     try:
@@ -48,14 +49,16 @@ def get_translation() -> gettext_module.NullTranslations:
         return _TRANSLATIONS[None]
 
 
-def activate(locale: str, path: str | None = None) -> gettext_module.NullTranslations:
+def activate(
+    locale: str, path: str | os.PathLike[str] | None = None
+) -> gettext_module.NullTranslations:
     """Activate internationalisation.
 
     Set `locale` as current locale. Search for locale in directory `path`.
 
     Args:
         locale (str): Language name, e.g. `en_GB`.
-        path (str): Path to search for locales.
+        path (str | pathlib.Path): Path to search for locales.
 
     Returns:
         dict: Translations.

tests/test_i18n.py

@@ -156,20 +156,20 @@ def test_ordinal_genders(
         humanize.i18n.deactivate()
 
 
-def test_default_locale_path_defined__file__() -> None:
+def test_default_locale_path_defined__package__() -> None:
     i18n = importlib.import_module("humanize.i18n")
     assert i18n._get_default_locale_path() is not None
 
 
-def test_default_locale_path_null__file__() -> None:
+def test_default_locale_path_null__package__(monkeypatch: pytest.MonkeyPatch) -> None:
     i18n = importlib.import_module("humanize.i18n")
-    i18n.__file__ = None
+    monkeypatch.setattr(i18n, "__package__", "")
     assert i18n._get_default_locale_path() is None
 
 
-def test_default_locale_path_undefined__file__() -> None:
+def test_default_locale_path_undefined__file__(monkeypatch: pytest.MonkeyPatch) -> None:
     i18n = importlib.import_module("humanize.i18n")
-    del i18n.__file__
+    monkeypatch.delattr(i18n, "__package__")
     assert i18n._get_default_locale_path() is None
 
 
@@ -179,17 +179,21 @@ class TestActivate:
         " 'locale' folder. You need to pass the path explicitly."
     )
 
-    def test_default_locale_path_null__file__(self) -> None:
+    def test_default_locale_path_null__package__(
+        self, monkeypatch: pytest.MonkeyPatch
+    ) -> None:
         i18n = importlib.import_module("humanize.i18n")
-        i18n.__file__ = None
+        monkeypatch.setattr(i18n, "__package__", "")
 
         with pytest.raises(Exception) as excinfo:
             i18n.activate("ru_RU")
         assert str(excinfo.value) == self.expected_msg
 
-    def test_default_locale_path_undefined__file__(self) -> None:
+    def test_default_locale_path_undefined__file__(
+        self, monkeypatch: pytest.MonkeyPatch
+    ) -> None:
         i18n = importlib.import_module("humanize.i18n")
-        del i18n.__file__
+        monkeypatch.delattr(i18n, "__package__")
 
         with pytest.raises(Exception) as excinfo:
             i18n.activate("ru_RU")