cargo test -- --logfile should support common CI formats

[lzybkr]

It would be useful if cargo test -- --logfile would write a file in a format supported by CI systems.

Based on AppVeyor and VSTS, it looks like junit or xunit3 could be good choices.

[alexcrichton]

Thanks for the report! I think this has to do with libtest moreso than Cargo though in the rust-lang/rust repo, so want to move the issue over there?

[lzybkr]

Done. rust-lang/rust#51924

It looks like json output is already available in nightly builds which might be helpful in the interim: rust-lang/rust#46450

[alexcrichton]

Ok! I'm gonna close this in favor of that issue