Bring multiple test filtering to test/bench

[dwijnand]

When more than one TESTNAME/BENCHNAME is specified, run the tests / doctests / benches once per name, passing the rest of the arguments to each invocation. So, for instance

cargo test foo bar --nocapture

Will test foo with --nocapture first and then bar with --nocapture.

[rust-highfive]

r? @ehuss

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[alexcrichton]

I would personally be wary of changing a public interface like this, especially with custom test frameworks somewhat on the horizon I think we'd want a broader discussion of how to map arguments to cargo test down to the actual test frameworks and such.

[dwijnand]

I've not followed what the custom test framework work has done, but I've felt the need for this feature many times! (see a few comments of mine in rust-lang/rust#30422)

How can I enable this to move forward?

[bors]

☔ The latest upstream changes (presumably #6683) made this pull request unmergeable. Please resolve the merge conflicts.

[alexcrichton]

I'm unfortunately not sure of the best way to move this forward, but I think a discussion on internals would probably be a good place to start? That might help rope in other folks interested in this area

[dwijnand]

Hmm, I'm not sure I want to spend my time trying to rally people.

I think instead I'll build this as an external command (as soon as I'm motivated enough). That way I can iterate outside of the bounds of cargo's CLI compatibility guarantees, avoid forcing anyone into accepting this insta-stable feature and also get some exposure to the pitfalls and concerns that external command developers face.