Index: Lib/test/test_calendar.py
===================================================================
--- Lib/test/test_calendar.py	(revision 83065)
+++ Lib/test/test_calendar.py	(working copy)
@@ -389,6 +389,32 @@
             tuple = time.gmtime(secs)
             self.assertEqual(secs, calendar.timegm(tuple))
 
+class MonthRangeTestCase(unittest.TestCase):
+    def test_january(self):
+        # tests valid lower boundary case
+        self.assertEqual(calendar.monthrange(2004,1), (3,31))
+
+    def test_february_leap(self):
+        # tests February during leap year
+        self.assertEqual(calendar.monthrange(2004,2), (6,29))
+
+    def test_february_nonleap(self):
+        # tests February in non-leap year
+        self.assertEqual(calendar.monthrange(2010,2), (0,28))
+
+    def test_december(self):
+        # tests valid upper boundary case
+        self.assertEqual(calendar.monthrange(2004,12), (2,31))
+
+    def test_zeroth_month(self):
+        # tests low invalid boundary case
+        self.assertRaises(calendar.IllegalMonthError, calendar.monthrange, 2004, 0)
+
+    def test_thirteenth_month(self):
+        # tests high invalid boundary case
+        self.assertRaises(calendar.IllegalMonthError, calendar.monthrange, 2004, 13)
+    
+
 def test_main():
     support.run_unittest(
         OutputTestCase,
@@ -396,6 +422,7 @@
         MondayTestCase,
         SundayTestCase,
         TimegmTestCase,
+        MonthRangeTestCase,
     )