After bug 1320194, it is no longer an error to try to resolve tests without a build context. Since |mach try| with test paths uses this test resolver, it means |mach try| can have unexpected behaviour without a full build backend. In the best case, it will could unexpectedly error out saying "no tests found". In the worst case, it could still push to try, but certain tasks the developer expected wouldn't show up. This is only a problem if specifying test paths, e.g: ./mach try -b o -p linux -u mochitests dom/indexedDB We should simply error out (like we did before bug 1320194) if no config.status is detected.

Comment on attachment 8841567 [details] Bug 1342937 - Error out of |mach try| when using test paths and no build config is detected, https://reviewboard.mozilla.org/r/115734/#review117282

Pushed by ahalberstadt@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/6c1627e91713 Error out of |mach try| when using test paths and no build config is detected, r=chmanchester