Adding testing framework

[labithiotis]

Added a testing framework, at the moment this PR just covers the templates dir, but will add index and file test if you are happy with it in another PR.

[CVarisco]

Hi @labithiotis,

thanks for your contribution 🙂 Now I'm editing the package in this way: "test": "jest" and "test:watch": "jest --watch"

Another thing, I create a __tests__ folder to insert the tests.

Thanks again @labithiotis

[CVarisco]

I follow the convention of naming and folders from the official documentation of jest.

• Folder that contains tests __tests__
• Every single file is name with NAME.test.js

[CVarisco]

Good job @labithiotis ! I'm merging the new branch triptease-dl/add-test

Thanks