---
_db_id: 267
available_flavours:
- any_language
content_type: project
pre: '<b>EASY: </b>'
ready: true
submission_type: repo
title: factorials
---

Write a script with a function called `calculate_factorial` that takes a number and returns its factorial.

In a separate file, write some tests that prove that your code works.

## Javascript instructions

- Name your script `factorial.js`
- Use `jasmine` to test your code

## Python instructions

- Name your script `factorial.py`
- Use `pytest` to test your code

## Steps:

- Think about which tests you want to do to test that the factorial function works.
- Write the tests **first** (before creating the function).
- Test an empty function called factorial - it should fail the tests
- Add code for returning the factorial of a number - it should pass for numbers >= 1
- Add code for dealing with zero - should pass unit test for zero and for numbers >= 1
- Add code for dealing with negative numbers
- Add code for dealing with non-numeric input

Make sure you use Github to keep track of your progress.

## References:

[Factorial Numbers](https://whatis.techtarget.com/definition/factorial)