Add a RUN-FAIL command?

[sheredom]

First off - thanks for this awesome lib - so cool that someone already thought about bringing the power of lit to cargo!

One thing I'm using this for is to assert that when a command fails a specific error message is printed out (for a little compiler project I'm working on). At the minute I'm having to do:

// RUN: my_command_that_fails || echo xfail

Is there any chance we could add something like RUN-FAIL or RUN-XFAIL that didn't throw an error if the executable returned non-zero?

[dylanmckay]

Thanks! Yes, LLVM's lit is the best general purpose testing tool I've used.

How does LLVM do this?

If you want to mock something up, I'm happy to review/merge it.

[sheredom]

I totally forgot to do anything here sorry. Honestly in the end I just used bash's failing_exe | echo to ensure a 0 return, worked fine!