This is quite a broad question. What is your biggest issue?

I'm going to go ahead and assume it is actually getting a browser to start on you CI server and getting the results.

For that there are a number of options, easily found by searching for continuous intergration, javascript and unit test.

I found Running JavaScript unit tests headlessly in a Continuous Integration build here on stackoverflow. This question has a good answer that you should be able to adapt for use with gradle.