Tutorial 8

This tutorial we’ll practice writing Tests for our functions.

We will write a function that calculates whether or not a particular year is a leap year. This is how the Gregorian calendar calculates leap years:

• If the year is divisible by four, it’s a leap year
• But if the year can be divided by 100 as well as four, it’s not a leap year
• However, if the year is divisible by 400, it is a leap year

Write a function named is_leap. It should:

• Take in a number as an input
• Return a value for True if it is a leap year
• Return a value for False if it is not a leap year.

Here are some examples of what the function should return:

• 1992: True
• 2000: True
• 1900: False
• 2021: False

In addition from the above examples, here are some test cases you should write as well

• Return an error if the user puts in the value of 0
• Return an error if the user puts in a negative value
• Returns an error if the user puts in a string

What are some other edge cases you can think of?

R

1. Write an R function that meets the above criteria
2. Using {testthat} write unit tests that can test your function
3. You may opt to source your function file in your test file.

Python (optional)

1. Write an R function that meets the above criteria
2. Write tests for your function that can be run with pytest
3. For this tutorial, create your function and test files in the same directory, so it’s easier to import your function module for testing.