One outcome of Heisenburg’s uncertainty principle is, that in quantum mechanics anyway, the act of making an observation can affect the very thing you are trying to observe. Of course at the equipment level, testing does not usually affect performance unless you happen to be using a low impedance voltage tester often referred to as a Wiggy tester. We have to be very careful about using this type of tester as we troubleshoot equipment as it can cause havoc with the performance of the observed component. Take a look at this BIT on the subject. Just an example from our large ever growing library of B.I.T.S.
https://kvgo.com/Example/wiggy-tester