[Alan Anderson]

There is a 5V supply built in to the Analog Breakout. If all you want to do is make sure your program can tell the difference between 5V and 0V on the analog input pin, that's easy. Each input channel's three-pin connector contains both 5V and 0V. All you would need is a switch to connect the signal pin to either the center 5V pin or the opposite 0V pin.

The exact same switch setup can test the digital inputs on the Digital Sidecar.