Add support for doctests

[Freax13]

• detect doctests as tests

[phil-opp]

Thanks for the PR! Could you clarify how you're using doc tests with bootimage? As far as I know, doc tests don't work in combination with custom test frameworks.

[Freax13]

first of all I should note that this isn't working rn because of a bug in cargo (rust-lang/cargo#8094)

i'm using something similar to cargo xtest --target bare_x86_64.json -Z doctest-xcompile to run the doctests

doctests don't work with custom test frameworks. rustdoc basically just individually wraps the code for each test in a main method (unless you provide your own) and compiles it.

example from my code:

/// acquire the lock
/// ```
/// # #![cfg_attr(target_os = "none", no_std, no_main)]
/// # lemon_std::entry_point!(test);
/// # async fn test() {
/// # use lemon_std::sync::SpinMutex;
/// let lock = SpinMutex::new("Foo");
/// lock.lock();
/// # lemon_std::arch::exit(true);
/// # }
/// # main();
/// ```
pub fn lock(&self) -> SpinMutexGuard<'_, D> {

[phil-opp]

Thanks for the clarification! I wasn't aware of the -Z doctest-xcompile, but it's great to see that docstests are coming to no_std applications.

doctests don't work with custom test frameworks. rustdoc basically just individually wraps the code for each test in a main method (unless you provide your own) and compiles it.

So they're basically integration tests with disabled test harness (as described in https://os.phil-opp.com/testing/#no-harness-tests)?

first of all I should note that this isn't working rn because of a bug in cargo (rust-lang/cargo#8094)

I think it might make sense to delay merging this PR until this cargo bug is resolved and we can actually try whether this PR works. It might be also a good idea to add an automated test for this then to check the behavior on CI and ensure that we don't break it on future changes. Would that be okay with you?

[Freax13]

So they're basically integration tests with disabled test harness (as described in https://os.phil-opp.com/testing/#no-harness-tests)?

pretty much, yeah

I think it might make sense to delay merging this PR until this cargo bug is resolved and we can actually try whether this PR works.

rust 1.43 just got released, so the latest cargo on nightly finally contains the fix. do you want me to write an example for doctests (probably something similar to test-basic-boot)?

[Freax13]

?

[phil-opp]

Sorry for the delay! Yes, I think some example that is tested on CI would be great.

[phil-opp]

There are a few warnings for the new doctest test, otherwise this looks very good.

[Freax13]

that should have got rid of the warning

[phil-opp]

Awesome, thanks a lot!

[phil-opp]

Published as v0.7.10