Our current mochitests on Mulet are run in-process, just like desktop Firefox. We also want to run them out-of-process, in a Gaia app, just like we do for b2gdesktop. This almost works right now, but the tests still run in the main screen after generating this error: JavascriptException: JavascriptException: TypeError: homescreen is null stacktrace: execute_script @runtestsb2g.py, line 290 inline javascript, line 22 src: "let container = homescreen.contentWindow.document.getElementById('test-container');" I think it's likely a timing issue.

That seems to be running ?

What's currently running is the same as mochitest on (non-e10s) desktop Firefox. What used to be running on b2gdesktop was mochitest inside a Gaia OOP test container app. I'm not sure whether that's still needed or not.

Comment on attachment 8665717 [details] [diff] [review] Bug XXX - Running Mochitest OOP on Mulet r=... Review of attachment 8665717 [details] [diff] [review]: ----------------------------------------------------------------- Looks good. ::: b2g/app/b2g.js @@ +296,5 @@ > // Layers Acceleration. We can only have nice things on gonk, because > // they're not maintained anywhere else. > pref("layers.offmainthreadcomposition.enabled", true); > #ifndef MOZ_WIDGET_GONK > +pref("dom.ipc.tabs.disabled", false); This is already set to false when --oop at https://dxr.mozilla.org/mozilla-central/source/b2g/components/OopCommandLine.js#42; is this still needed?