Set up testing environment

[jrobind]

I'd recommend using jest, but open to discussions on this.

This issue could cover just the testing setup and configuration.

In terms of actually writing some meaningful tests for our code, this will probably require a bit of extra work and refactoring. We might need to move our JS logic into a class which will make testing methods/functionality much easier.

[mamadou-diallo]

I'll take care of this

[jrobind]

Thanks! 👍

[jrobind]

Closed by #52