I know this link adds munit support in Studio
http://studio.mulesoft.org/r4/munit
but is there another plugin for eclipse? Confirming as it specifically says Studio plugin
That link is correct. MUnit Studio Plugin, requires the Studio platform to work.
It hasn't been designed to work in a plain vanilla Eclipse. Then again I reckon that if you manage to install all the required plugins it should work but you'll end up with basically with Studio again.
HTH