In the zip file you will find:

1. "random node.blend" file with simple random node and placeholder testing scene
2. "random C.blend" file with advanced C-inspired random node and placeholder testing scene
3. "random nodes featured.blend" file with featured animation gif scene for educational purposes.

Usage:

File -> Append -> select one of aformentioned files -> NodeTree -> select random shader or texture node.

After appending the node group, you can add it to the shader node editor

Add -> Group -> select the node