assertion.py

# By Websten from forums
#
# Given your birthday and the current date, calculate your age in days. 
# Compensate for leap days. 
# Assume that the birthday and current date are correct dates (and no time travel). 
# Simply put, if you were born 1 Jan 2012 and todays date is 2 Jan 2012 
# you are 1 day old.
#
# Hint
# A whole year is 365 days, 366 if a leap year. 

def nextDay(year, month, day):
    """Simple version: assume every month has 30 days"""
    if day < 30:
        return year, month, day + 1
    else:
        if month == 12:
            return year + 1, 1, 1
        else:
            return year, month + 1, 1
        
def dateIsAfter(year1, month1, day1, year2, month2, day2):
    """Returns True if year1-month1-day1 is after year2-month2-day2.  Otherwise, returns False."""
    if year1 > year2:
        return True
    if year1 == year2:
        if month1 > month2:
            return True
        if month1 == month2:
            return day1 > day2
    return False        

def daysBetweenDates(year1, month1, day1, year2, month2, day2):
    """Returns the number of days between year1/month1/day1
       and year2/month2/day2. Assumes inputs are valid dates
       in Gregorian calendar."""
    # program defensively! Add an assertion if the input is not valid!


    assert ((year1<year2)or((year1==year2)and(month1<=month2)and(day1<=day2)))


    days = 0
    while dateIsAfter(year2, month2, day2, year1, month1, day1):
        days += 1
        (year1, month1, day1) = nextDay(year1, month1, day1)
    return days

def test():
    test_cases = [((2012,9,30,2012,10,30),30), 
                  ((2012,1,1,2013,1,1),360),
                  ((2012,9,1,2012,9,4),3),
                  ((2013,1,1,1999,12,31), "AssertionError")]
    
    for (args, answer) in test_cases:
        try:
            result = daysBetweenDates(*args)
            if result != answer:
                print ("Test with data:", args, "failed")
            else:
                print ("Test case passed!")
        except AssertionError:
            if answer == "AssertionError":
                print ("Nice job! Test case {0} correctly raises AssertionError!\n".format(args))
            else:
                print ("Check your work! Test case {0} should not raise AssertionError!\n".format(args))            
test()