I do have a couple tools for testing.

For way too long I used one of these cheap pieces of crap. There's dozens of versions of it sold in every computer store and they're the biggest pieces of junk I've used in my work. They fail all the time, usually by starting to fail on one pin reading, making you redo your terminations a couple times before you realize it's the tool and not your work. I went through about 5 of them before I wised up and finally spent some money.

So now my main workhorse is this guy. Certainly not the gold standard, but it's been solid for me and make life so much easier as a one-man shop. I love being able to plug in 8 probes and ID/test them all in one fell swoop instead of walking back and forth to each jack. It makes cleaning up a network closet so much easier. And I've used the coax testing end for home users too. I love this one.

But I needed something more. Something with a little more power and capabilities but without breaking the bank (basically something under $1-3K, preferably under $500). I took a chance on this one. So far...the jury is still out. I like it, and there's some neat stuff it can do like show DHCP leasing, detect POE, and it can actually do link speed testing. The main reason I wanted something like this though was for distance to fault readings. I get that this is tricky but so far I haven't had great results. It had to be calibrated because the out of the box readings were so completely off. So I made a cable of the exact length they recommended and did the calibration, then I made a second cable and snipped a couple of the strands to test it, and it was about five feet off, which can make a big difference when stuff is going behind drywall. It's tough because it depends so much on the type of cable and even which pair is the issue. I also haven't used any other tools that can do this so I don't know if this one is better or worse at it.

Anyway, that's pretty much my toolkit for testing, other than your basic Fluke toner kit which I probably use more than anything.

***edit***
Also, I ordered that last one from some UK-based startup. I have no idea of their credentials. I think the device is pretty much a Raspberry Pi in a slick aluminum case, so it just barely has a better feel to it than a hobby kit.

***edit2***
The Pockethernet can at least do cable qualification and verification, but not certification.