The biggest downside to |mach try| is that you need to have an objdir to make use of the test path feature. This negates one of the benefits of try, the fact that you don't need to build locally to test things out. In the long run, it would be cool if we could somehow resolve tests just using a srcdir (not sure if this is possible or not). In the short term, it would be nice if invocations that just use vanilla try parameters don't interact with the build system at all.

I just hit this today, this would have been useful! I think you *could* resolve tests using a srcdir if you were willing to evaluate all the moz.build files locally. That would be faster than doing an actual build, so might be worthwhile. In the short term just skipping this step if you don't specify test paths would be great.

Resolving tests without a build is something I tried to solve over in bug 1184405 without much success, but should ultimately be doable. Having a way to run tests without re-building has been requested before. But I've been burned by this a few times too, let's go with the straightforward patch for now.

Bug 1197829 - Don't invoke the build system if paths or tags aren't passed to mach try. r=ahal

Comment on attachment 8652623 [details] MozReview Request: Bug 1197829 - Don't invoke the build system if paths or tags aren't passed to mach try. r=ahal https://reviewboard.mozilla.org/r/17237/#review15359 Ship It!