How to render .vm to HTML from mock issue in Jira plug-in in test mode?

Dear Developers!

I have very interesting situation, and my question rather theoretical.

My story is about plug-in for Jira. I want to test email's body rendering before sending .vm file to production. For testing I want to use MockIssue.

For rendering .vm I used this source: http://ift.tt/1SvdQEu

But in this case I can only to give a context values... So for now I have no vorking code.

Have you any ideas or suggestions how to do it? Or had someone similar issues?

Thanks for any help or ideas! :)