Add library path argument for mdbook test

[messense]

Add -L/--library-path argument and pass it into rustdoc should be sufficient.

Closes #339

[azerupi]

Is this going to work okay when no arguments are passed?

[messense]

Yes. With no/empty arguments, it simply returns self.

https://github.com/rust-lang/rust/blob/master/src/libstd/process.rs#L403

[azerupi]

Thanks!
I just have a simple question before merging, see inline comment. :)

[messense]

It's a little annoying that tuple does not implement IntoIterator trait, causing this vec![x.0, x.1] nonsense.

[azerupi]

Thanks! And sorry for the delay :)

[Michael-F-Bryan]

It may be a good idea to thread this through the configuration system so you aren't continually writing the "-L" arguments.

When #371 lands I'll move onto tidying up configuration and see if I can add an extra "tests" table to the book.toml file for adding parameters to tests like external dependencies. We've just got to think of a way to configuration so it's scalable to multiple backends and plugin systems (html, pdf, rustdoc testing, mathjax, etc) and not special casing everything like we are now.

[azerupi]

@Michael-F-Bryan I don't see this as a permanent solution. The test command is currently just a wrapper around rustdoc, maybe with some additional checks, because it was needed for the Rust book. But ideally we would want this to be configurable and extendable by the user. Because there is no way we can anticipate everything the user would want to "tests".

[Michael-F-Bryan]

But ideally we would want this to be configurable and extendable by the user.

My thoughts were that you could add something like this to your book.toml:

[test]
runner = "rustdoc"
dependencies = ["error-chain", "rayon"]

To me the test runner is pretty much just an alternate renderer, except instead of rendering content it'll give you a pass or a fail (because a Renderer returns a Result).

Otherwise if you have your own custom test script it might be invoked like this:

[test]
runner = "shell"
command = "test_docs.py"

EDIT: Note that this would be more of a long-term goal. It relies on a more flexible system for rendering and configuration than what currently exists.

[azerupi]

That would be nice indeed!

[budziq]

On the other hand rust-cookbook uses https://github.com/brson/rust-skeptic/. We never invoke mdbook test just using cargo test (extern crates are handled by cargo dependencies then) which imho is generally better approach if the mdbook is kind of insource/inrepo documentation (it nicely integrates with rest of the tests).

But I understand why mdbook test might be useful in other contexts.

[budziq]

Hmm on the other hand I do not see a better way (I mean this general approach suggested by @Michael-F-Bryan) to support spell checking and link checking which are very much desired. So big 👍