unit test for all the controllers

[HeeManSu]

We should implement unit tests for all controllers to guarantee their proper functionality in the future.

[vr-varad]

@viferga I would like to work on it. could u please assign me this issue?

[viferga]

I prefer if we do integration tests directly. Unit tests are usually a nightmare to maintain and they only serve to develop the software itself, verify bugs in specific places or verify complex algorithms. I think @HeeManSu is working already on this, it would be cool if you push your changes as a draft. Later on I can set up integration tests on top of the unit testing.