They had been testing the BOP but at lower than normal pressures. On safety and procedures the BP rigs are a big fail, apparently they have had 700 odd infractions and Exxon Mobil only 1. I don’t have numbers on comparable numbers of rigs though. Right now it seems as if BP lives on the edge that others won’t go near.
Yes, I can see that the test has to be at the right pressure, which means at the sea floor and the pipe has to be what they are using — I heard that the pipe from China was not to specs.
As far as the total number of infractions, BP has some explanation that they all came from two basic troubled rigs, and presumably from two troubled managers. However, in the big picture, it would appear that BP lives farther out on the edge, and in particular— did not appreciate that they were also (to use a pun) in uncharted waters with Deepwater Horizon.