The mbunit function in rubicant has been changed from just a function to a complete task.
Behind the scenes, what MBUnitTask does is copies over the minimal necessary support files from an MBUnit directory and then runs the tests. It uses the MBUnit Console Runner and is only tested with MBUnit 2.4. It is used as follows:
Runs the tests in test_files in the test_dir with the dlls from mbunit_dir using the options in opts.
For more information on the command line arguments for the mbunit console runner, please visit: http://docs.mbunit.com/help/html/gettingstarted/MbUnitConsoleRunner.htm