Adafruit Multifunctional USB Digital Tester - USB A and C [ADA4232]
While this may appear to be an electronic shuriken , it's actually a Multifunctional USB Digital Tester !
This handy (pun intended?) tool can measure voltage, current, power, charge time, and other measurements for USB A, Micro B, and USB C ! It features a colorful display that pops up when you plug in a power supply. Each click of the button gives you a different display and readout. A long press will reset the data for when it does Coulomb-counting (total power consumption). We like the simple display that comes up first with big Voltage and Current output, but you have lots of options.
There's 4 connectors so you can go from type A to C, type A to A or type C to C.
Works great with laptops, smartphones, tablets, what have you, it's perfect for testing any USB power setup but this model is a little nicer in that it is also good for USB C with its higher current and voltage capabilities - up to 32V and 5A!
If you're using this to test USB C be sure to get a cable with E-Mark power negotiation chips inside so you get the proper current and voltage out - many cheap USB C cables skip this part and won't work well for high-current/voltage charging.