It is heavy to download and run the full Activepieces code base to just create or update a piece. Pieces should act as blackbox and only be concerned about the input and output. As such, it would be so much easier for engineers to use a lighter weight developer harness that allows them to create and manage pieces in complete isolation without the need for the entire platform.
Along with this, it would then be good to have a way to implement unit tests for pieces so they can be tested in a more uniform way between releases. As Activepieces continues to grow piece maintenance and validation is going to become more critical to ensure pieces are always functional.
Some of this may already exist and I have missed it…
Interesting, How would you see the end result / test while develop? how do you imagine it 
At a high level, I can see a developer simply install the development SDK as a CLI tool which is a light weight harness that will essentially run a piece - similar to what Zapier has.
Using the CLI you could:
- Initiate a scaffolded new piece
- Run a piece during development to ensure it works.
- Write tests against the piece to ensure it is functioning as expected on a continual basis and through updates.
- Package and deploy a piece to either the community or private.
The piece tests could also be used to see if a piece could run on specific versions of Activepieces or not - this will help upgrade paths in the future.
Ideally pieces would all have tests that ship with them so the tests can be run upon install, update etc.
Having this type of framework would allow engineers to rapidly develop and maintain pieces in complete isolation.