You cant really test for polaritys with a tool apart from a multimeter
You cant just have a pin and you touch it and it tells you if its positive or negative
But what you can do is connect one pin to GND, then with the positive connection, touch it on the pins, if the multimeter reports voltage going through it, you just found your positive point, then vice versa you will find negative too
And to test for polarity, you can do with a multimeter too, say you have 2 wires, both same colour in the PSP so your not sure which one is positive, just put a multimeter lead on each end, and make it detect voltage, if its a positive voltage its the correct polarity (black wire=gnd, red wire=+) but if its a negative number (eg -4 volts) then its the wrong way round