13.58QA-to-developer connection

Your existing test instincts translate almost one-to-one:

Playwright/API test concept     MUnit

fixture                     →   Set Event/test resources

API mock                    →   Mock When

expect(...)                 →   Assert That

spy/mock verification       →   Verify Call

helper                      →   test flow/subflow

simulate 500               →   mock connector error

test branch                →   Choice-path MUnit test

The main difference is that you're now testing inside the Mule application rather than only through its external endpoint.