diff -r 6b70f16d585a Lib/calendar.py
--- a/Lib/calendar.py	Wed Apr 15 10:27:58 2015 -0400
+++ b/Lib/calendar.py	Thu Apr 16 09:16:41 2015 -0500
@@ -12,7 +12,9 @@
 __all__ = ["IllegalMonthError", "IllegalWeekdayError", "setfirstweekday",
            "firstweekday", "isleap", "leapdays", "weekday", "monthrange",
            "monthcalendar", "prmonth", "month", "prcal", "calendar",
-           "timegm", "month_name", "month_abbr", "day_name", "day_abbr"]
+           "timegm", "month_name", "month_abbr", "day_name", "day_abbr",
+           "Calendar", "TextCalendar", "HTMLCalendar", "LocaleTextCalendar",
+           "LocaleHTMLCalendar", "weekheader"]
 
 # Exception raised for bad input (with string parameter for details)
 error = ValueError
diff -r 6b70f16d585a Lib/test/test_calendar.py
--- a/Lib/test/test_calendar.py	Wed Apr 15 10:27:58 2015 -0400
+++ b/Lib/test/test_calendar.py	Thu Apr 16 09:16:41 2015 -0500
@@ -815,5 +815,25 @@
                       b'href="custom.css" />', stdout)
 
 
+class MiscTestCase(unittest.TestCase):
+
+    def test__all__(self):
+        blacklist = {'SUNDAY', 'February', 'main', 'mdays', 'January',
+                     'TUESDAY', 'THURSDAY', 'FRIDAY', 'error', 'c',
+                     'formatstring', 'WEDNESDAY', 'SATURDAY',
+                     'different_locale', 'MONDAY', 'EPOCH', 'week',
+                     'format', 'prweek'}
+        exported = set(calendar.__all__)
+        possible_exports = set()
+        import types
+        for name, value in calendar.__dict__.items():
+            if name.startswith('_'):
+                continue
+            if isinstance(value, (types.ModuleType,)):
+                continue
+            possible_exports.add(name)
+        self.assertEqual(exported, possible_exports - blacklist)
+
+
 if __name__ == "__main__":
     unittest.main()