Unit testing setup

[Luca Toldo]

Dear JenkinsDevs,
I want to do a minor extension of hashicorp-vault-plugin, adding the "write" capability.

This is my first Jenkins Plugin and I am facing issue with unit testing.

I documented that within the specific plugin component however I think that 

what I face is general ...

https://github.com/jenkinsci/hashicorp-vault-plugin/issues/140

I am using Eclipse as IDE, and would very much appreciate technical detailed advise on how to properly do that.

Thankyou