How can I unit test my grunt plugin?

I made a grunt plugin for specific build needs. The first version is quite good but it still needs some improvements. So, I'd like to develop unit tests for the plugin, so it can evolve safely in the future.

How can I unit test my grunt plugin ? I don't have any idea about where to begin and I didn't find any correct guide online.

I tried looking at existing plugin sources, but it's all very muddled.