I test a lot of gear, for myself and for manufacturers. With the exception of footwear (which gets a few walks near my house first) I just use it in my normal activity. If the test kit has problems, I just have to cope - all the rest of what I'll have with me is tried and tested. Even a complete failure of waterproofs like I had recently just means I'm a bit uncomfortable for the day (OK, it was minus 2 with wind chill, but I just kept moving - I did have sufficient spare kit in case of emergency).
I did used to do the standing in shower with waterproofs, but I found things would pass that but fail while walking. For things like drybags, I do still fill them with water first, but that is more to decide what level of use to put them to (last week I was given a new one to test, I was going to take it on a SUP journey yesterday, but the seal failed the fill test so I'll use it inside a rucksack on my next heavy rain walk instead).