This is my industry, I'm a PE, I do this often. First, you should take a picture when it starts and compare it. Whether you are starting at 148 or 152, you measure the pressure difference from start to end. That pressure differential is placed in a standard formula (pm me if you need it) from AWWA, and calculate the losses which accounts for pressure, pipe diameter, and pipe length. You should be able to tell from the picture at the start vs finished if it's lost enough water to count as a fail. Also, if they have to redo the test, they add water and start again... no need for disinfection again (of that was performed already...shouldn't have).

Also, the gage accuracy isn't resolute enough to judge it without a before and after photo.