Abstract: The present invention provides systems and methods for performing production testing in open holes and in cased holes that avoid transporting formation fluid to the surface. The invention essentially comprises a test string for testing a production zone intersecting a wellbore. The string further comprises a fluid communication member allowing flow of fluid therethrough, a sealing device for isolating a production zone intersecting said wellbore to allow fluid flow from said production zone into said fluid communication member, a second sealing device spaced apart from said first sealing device for isolating a second injection zone intersecting said wellbore, a pump for pumping fluid between zones, and flow control devices.