Advanced users can create a DLL model using the Proteus VSM SDK. This allows debugging of actual NeoPixel library code.
This is where comes in. Proteus is a powerful software for electronic design automation (EDA) that includes schematic capture, PCB layout, and—most importantly—interactive simulation. But there's a catch: Proteus does not include the WS2812 library by default.
Adafruit_NeoPixel pixels(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);