[3.13] gh-130655: gettext: Add fallback testcase (GH-136857) (#136863)

gh-130655: gettext: Add fallback testcase (GH-136857)
(cherry picked from commit c6e6fe9)

Co-authored-by: Dominic H <[email protected]>

Author: miss-islington

Lib/test/test_gettext.py

@@ -981,6 +981,13 @@ def test__all__(self):
                              not_exported={'c2py', 'ENOENT'})
 
 
+class TranslationFallbackTestCase(unittest.TestCase):
+    def test_translation_fallback(self):
+        with os_helper.temp_cwd() as tempdir:
+            t = gettext.translation('gettext', localedir=tempdir, fallback=True)
+            self.assertIsInstance(t, gettext.NullTranslations)
+
+
 if __name__ == '__main__':
     unittest.main()