gh-69714: Restore the test thrown out by cb0523e

Author: bxsx

Lib/test/test_calendar.py

@@ -559,11 +559,27 @@ def test_locale_calendars(self):
         self.assertEqual(len(local_weekday), 10)
         self.assertEqual(len(local_weekday_abbr), 3)
         self.assertGreaterEqual(len(local_month), 10)
+
+        cal = calendar.LocaleTextCalendar(locale='')
+        local_weekday = cal.formatweekday(1, 10)
+        local_month = cal.formatmonthname(2010, 10, 10)
+        self.assertIsInstance(local_weekday, str)
+        self.assertIsInstance(local_month, str)
+        self.assertEqual(len(local_weekday), 10)
+        self.assertGreaterEqual(len(local_month), 10)
+
         cal = calendar.LocaleHTMLCalendar(locale=None)
         local_weekday = cal.formatweekday(1)
         local_month = cal.formatmonthname(2010, 10)
         self.assertIsInstance(local_weekday, str)
         self.assertIsInstance(local_month, str)
+
+        cal = calendar.LocaleHTMLCalendar(locale='')
+        local_weekday = cal.formatweekday(1)
+        local_month = cal.formatmonthname(2010, 10)
+        self.assertIsInstance(local_weekday, str)
+        self.assertIsInstance(local_month, str)
+
         new_october = calendar.TextCalendar().formatmonthname(2010, 10, 10)
         self.assertEqual(old_october, new_october)