ssisUnit is a great unit testing tool for the SSIS package. The only caveat I came across is that you need to run unit tests on a machine with SSIS server components installed. I work in a store where I have installed SSIS client components, but the server is deleted (I have Sql Server Express in my local field), so I can not use ssisUnit in my development. This means that I have to write my scripts manually, which is much more painful.