Rewrite tests using runServerless

[juanjoDiaz]

Current tests don't really test the full serverless pipeline.
We could use https://github.com/serverless/test/blob/master/docs/run-serverless.md to do so.

[Dhruv1107]

Hi @juanjoDiaz ,
This issue seems to be a good initiation of my journey towards contribution to FOSS projects.
Can you please assign this to me?

[juanjoDiaz]

Hi @Dhruv1107 ,

Feel free to start working on this and submit a PR as soon as you have something.
I'm happy to help in whatever I can. 🙂

Cheers!