SmartThings “Groovy API” is sufficiently documented for people who are extremely well versed in Groovy and who are able to have extraordinary patience in a non-debugging IDE (i.e., debugging via
log_debug() statements only: No breakpoints, variable analyzers, etc.).
And you must also understand it is not pure Groovy - it is a sandboxed environment, and it is pre-processed metadata, etc. … none of which is exposed to the Developer for accurate debugging.
So how to develop?
Visit the various Repos and/or Community shared SmartApps and find one that is closest to what you are interested in pursuing. Start with the simplest possible examples.
- Test it. Modify it. Test it. Modify it. Break it. Fix it. Repeat.
- Then find a more complex example. Goto #1.