Sounds very similar to the "interpreter" or "virtual machine" pattern (can't recall the exact name). But essentially a component receives a list of high level

Sounds very similar to the "interpreter" or "virtual machine" pattern (can't recall the exact name). But essentially a component receives a list of high level instructions / description of what the user wants done, and it translates that into descriptions of "lower level" commands that should be performed. And those commands then get executed separately. Anythinf statefule / io is contained in the commands and can be tested easily with external dependencies. And the complex logic is all pure in decided what to do and how to do it based on what was asked for.