Running end-to-end API tests in a local development environment (as well as in CI) should be easy. In particular, it should be trivial to set up and tear down a wiki instance that the tests run against. A containerized environment seems the obvious choice.
Notes:
- Perhaps this could be based upon Addshore's mediawiki-docker-dev project. This already provides an easy way to create a new wiki; adding a mechanism for quickly discarding a temporary wiki instance would perhaps be sufficient to complete this task.