old_contents: import unittest
  from lib import calendar
  
  
  class CalendarTests(unittest.TestCase):
      def testIsLeapYear(self):
          self.assertEqual(calendar.isLeapYear(1977), False)
          self.assertEqual(calendar.isLeapYear(1980), True)
          self.assertEqual(calendar.isLeapYear(1900), False)
          self.assertEqual(calendar.isLeapYear(2000), True)
          self.assertEqual(calendar.isLeapYear(6723), False)
  
      def testDaysInMonth(self):
          self.assertEqual(calendar.daysInMonth(1, 1974), 31)
          self.assertEqual(calendar.daysInMonth(2, 1980), 29)
          self.assertEqual(calendar.daysInMonth(2, 1981), 28)
          self.assertEqual(calendar.daysInMonth(4, 1981), 30)
  
      def testFirstDayDayNums(self):
          self.assertEqual(calendar.getFirstDaysInMonth(1974), [1, 32, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335])
  
  
  if __name__ == '__main__':
      unittest.main()
  
new_contents: import unittest
  from lib import calendar
  
  
  class CalendarTests(unittest.TestCase):
      def testIsLeapYear(self):
          self.assertEqual(calendar.isLeapYear(1977), False)
          self.assertEqual(calendar.isLeapYear(1980), True)
          self.assertEqual(calendar.isLeapYear(1900), False)
          self.assertEqual(calendar.isLeapYear(2000), True)
          self.assertEqual(calendar.isLeapYear(6723), False)
  
      def testDaysInMonth(self):
          self.assertEqual(calendar.daysInMonth(1, 1974), 31)
          self.assertEqual(calendar.daysInMonth(2, 1980), 29)
          self.assertEqual(calendar.daysInMonth(2, 1981), 28)
          self.assertEqual(calendar.daysInMonth(4, 1981), 30)
  
      def testFirstDayDayNums(self):
          self.assertEqual(calendar.getFirstDaysInMonth(1972), [1, 32, 61, 92, 122, 153, 183, 214, 245, 275, 306, 336])
          self.assertEqual(calendar.getFirstDaysInMonth(1974), [1, 32, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335])
          self.assertEqual(calendar.getFirstDaysInMonth(1975), [1, 32, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335])
  
  
  if __name__ == '__main__':
      unittest.main()
  
subject: add test for leap years day array