Adding test cases for dnsgen 'partiate domain'

[SrilakshmiSH]

Hello Patrik,

I have created a test file for partiate domain method using unittest module. I have considered different cases for valid and invalid domain names and have tested for special characters as well using assertEqual(). I'm a beginner in python and new to open source. This being my first contribution, I request you to suggest any improvements.

Thanks, Sri

[PatrikHudak]

Thanks for the PR, can you please move it to "tests/" folder in the root rather than "dnsgen/"?

Thanks