This test and others that you should perform beforehand are not just to avoid problems with tripping,they are also about covering yourself,if you work on an installation and then there is an issue and someone gets hurt it could be you in the dock,then try and explain why you didn't test.Last week I went to a commercial job to change a board,the supply cable was replaced 20 years ago and the install has been worked on since,however it would appear that I was the only one to test it as there was no earth,this was traced to a missing link in the cut out(pme).What annoyed me was not only had succesive sparks never tested it but neither had the dno when the feed was fitted.