Working 9 to 5

Whereas most countries use a 24-hour clock, the United States tends to use a 12-hour clock. Accordingly, instead of “09:00 to 17:00”, many Americans would say they work “9:00 AM to 5:00 PM” (or “9 AM to 5 PM”), wherein “AM” is an abbreviation for “ante meridiem” and “PM” is an abbreviation for “post meridiem”, wherein “meridiem” means midday (i.e., noon).

In a file called working.py, implement a function called convert that expects a str in either of the 12-hour formats below and returns the corresponding str in 24-hour format (i.e., 9:00 to 17:00). Expect that AM and PM will be capitalized (with no periods therein) and that there will be a space before each. Assume that these times are representative of actual times, not necessarily 9:00 AM and 5:00 PM specifically.

• 9:00 AM to 5:00 PM
• 9 AM to 5 PM

Raise a ValueError instead if the input to convert is not in either of those formats or if either time is invalid (e.g., 12:60 AM, 13:00 PM, etc.). But do not assume that someone’s hours will start ante meridiem and end post meridiem; someone might work late and even long hours (e.g., 5:00 PM to 9:00 AM).

Structure working.py as follows, wherein you’re welcome to modify main and/or implement other functions as you see fit, but you may not import any other libraries. You’re welcome, but not required, to use re and/or sys.

import re
import sys


def main():
    print(convert(input("Hours: ")))


def convert(s):
    ...


...


if __name__ == "__main__":
    main()

Either before or after you implement convert in working.py, additionally implement, in a file called test_working.py, three or more functions that collectively test your implementation of convert thoroughly, each of whose names should begin with test_ so that you can execute your tests with:

pytest test_working.py

Demo

Before You Begin

Log into cs50.dev, click on your terminal window, and execute cd by itself. You should find that your terminal window’s prompt resembles the below:

$

Next execute

mkdir working

to make a folder called working in your codespace.

Then execute

cd working

to change directories into that folder. You should now see your terminal prompt as working/ $. You can now execute

code working.py

to make a file called working.py where you’ll write your program. Be sure to also execute

code test_working.py

to create a file called test_working.py where you’ll write tests for your program.

How to Test

How to Test working.py

Here’s how to test working.py manually:

• Run your program with python working.py. Ensure your program prompts you for a time. Type 9 AM to 5 PM, followed by Enter. Your program should output 09:00 to 17:00.
• Run your program with python working.py. Type 9:00 AM to 5:00 PM, followed by Enter. Your program should again output 09:00 to 17:00.
• Run your program with python working.py. Ensure your program prompts you for a time. Type 10 PM to 8 AM, followed by Enter. Your program should output 22:00 to 08:00.
• Run your program with python working.py. Ensure your program prompts you for a time. Type 10:30 PM to 8:50 AM, followed by Enter. Your program should again output 22:30 to 08:50.
• Run your program with python working.py. Ensure your program prompts you for a time. Try intentionally inducing a ValueError by typing 9:60 AM to 5:60 PM, followed by Enter. Your program should indeed raise a ValueError.
• Run your program with python working.py. Ensure your program prompts you for a time. Try intentionally inducing a ValueError by typing 9 AM - 5 PM, followed by Enter. Your program should indeed raise a ValueError.
• Run your program with python working.py. Ensure your program prompts you for a time. Try intentionally inducing a ValueError by typing 09:00 AM - 17:00 PM, followed by Enter. Your program should indeed raise a ValueError.

How to Test test_working.py

To test your tests, run pytest test_working.py. Try to use correct and incorrect versions of working.py to determine how well your tests spot errors:

• Ensure you have a correct version of working.py. Run your tests by executing pytest test_working.py. pytest should show that all of your tests have passed.
• Modify the correct version of working.py, particularly its function convert. Your program might, for example, fail to raise a ValueError when it should. Run your tests by executing pytest test_working.py. pytest should show that at least one of your tests has failed.
• Similarly, modify the correct version of working.py, changing the return values of convert. Your program might, for example, mistakenly omit minutes. Run your tests by executing pytest test_working.py. pytest should show that at least one of your tests has failed.

You can execute the below to check your code using check50, a program that CS50 will use to test your code when you submit. But be sure to test it yourself as well!

check50 cs50/problems/2022/python/working

Green smilies mean your program has passed a test! Red frownies will indicate your program output something unexpected. Visit the URL that check50 outputs to see the input check50 handed to your program, what output it expected, and what output your program actually gave.

How to Submit

In your terminal, execute the below to submit your work.

submit50 cs50/problems/2022/python/working