Testing for Business Intelligence will use same processes and methodologies as any other testing.
From my experience the majority of output will be reports and dashboards both of which can be time consuming to verify but I have not seen anything special.
If you also have to verify data extract for Data Marts and Data cubes - especially those developed for end users to create their own report from you will have some extensive verifications to do - you can verify data by using BI reporting tools or SQL.
I have not failed. I've just found 10,000 ways that won't work" --Thomas Edison