Auto-tools/Projects/m21s

Introduction

m21s is the code name of the mozmill-marionette-e10s project, the project whose aim is to replace mozmill with e10s-compliant marionette tests. The project consists roughly of the following pieces:

• adapt marionette to e10s
• add features to marionette required by mozmill tests
• rewrite existing mozmill tests as marionette tests
• update the mozmill infrastructure and CI to utilize the new tests and harness

Many of these pieces can be done in parallel, but this is a significant project which will likely take multiple months to fully deliver.

Rationale

Mozmill is currently used for release and update testing by QA. It provides coverage not duplicated elsewhere, and sometimes finds important bugs. Mozmill was written long before e10s and features a model which includes promiscuous chrome-content interactions implemented in a way which is not trivial to port to an e10s-compatible model. Making mozmill e10s-compatible would involve updating the harness, the libraries and the test themselves.

Although this is achievable, there has been momentum building for the idea of migrating mozmill on top of marionette, to benefit from the stability of marionette's protocol. An evaluation of this idea has been performed, and it was determined that this solution would be difficult to implement and likely problematic as well. Combined with the requirement of e10s-compatibility, this idea was determined to be not worth the effort and has been abandoned in favor of simply rewriting all of the existing mozmill tests as marionette tests, after the necessary feature work to marionette has been accomplished.