Index: test/test_locale.py
===================================================================
--- test/test_locale.py	(Revision 74327)
+++ test/test_locale.py	(Arbeitskopie)
@@ -298,6 +298,16 @@
             grouping=True, international=True)
 
 
+class TestLocaleFormatString(unittest.TestCase):
+    """General tests on locale.format_string"""
+
+    def test_percentage(self):
+        self.assertEqual(locale.format_string('%f%%', 1.0), '1.000000%')
+
+        self.assertEqual(locale.format_string('%d %f%%d', (1, 1.0)),
+            '1 1.000000%d')
+
+
 class TestStringMethods(BaseLocalizedTest):
     locale_type = locale.LC_CTYPE
 
@@ -351,6 +361,7 @@
 def test_main():
     tests = [
         TestMiscellaneous,
+        TestLocaleFormatString,
         TestEnUSNumberFormatting,
         TestCNumberFormatting,
         TestFrFRNumberFormatting,