`./x test library/core` stopped working

[RalfJung]

This is a regression (for library contributors) caused by #135937: running ./x test library/core will no longer actually run most of the tests, it just runs doc tests. It looks like it is doing something, so it is quite easy to miss that it doesn't actually do what I asked it to do.

Cc @rust-lang/libs @bjorn3 @tgross35

[jieyouxu]

Oh, this comes back to the iffy Crate step...

[jieyouxu]

I'll take a look at this.

[RalfJung]

Is it? The tests are literally not in library/core any more, they are in library/coretests now. But one has to somehow know that...

[jieyouxu]

Is it? The tests are literally not in library/core any more, they are in library/coretests now. But one has to somehow know that...

I think what happened is that previously, ./x test library/core is matched against the Crate step via run.crate_or_deps("sysroot") in Crate::make_run, which resolves to a crates=["core"] that will get tested. This included the bits that are in coretests since they were previously in the same crate (which caused issues that motivated moving to coretests).

However, when core tests were moved to coretests, the resolution was handled via run.crate_or_deps("sysroot").crate_or_deps("coretests"), which:

• Resolves still to crates=["core"] if the path filter is ./x test library/core.
• Resolves now to crates=["coretests"] if the path filter is ./x test coretests.

On master

$ BOOTSTRAP_TRACING=bootstrap=debug ./x test library/core
Building bootstrap
 [...]
 bootstrap::Build::build
  [...]
     bootstrap::(2) executing actual run
       bootstrap::core::build_steps::test::Crate::make_run
        [...]
        DEBUG bootstrap::core::build_steps::test crates=["core"]
[...]
Testing  {core} (stage1 -> stage2, x86_64-unknown-linux-gnu)

$ BOOTSTRAP_TRACING=bootstrap=debug ./x test coretests
Building bootstrap
 [...]
 bootstrap::Build::build
   [...]
   bootstrap::executing real run
     [...]
     bootstrap::(2) executing actual run
       bootstrap::core::build_steps::test::Crate::make_run
        [...]
        DEBUG bootstrap::core::build_steps::test crates=["coretests"]
         [...]
[...]
Testing  {coretests} (stage1 -> stage2, x86_64-unknown-linux-gnu)

Before moving to coretests

$ BOOTSTRAP_TRACING=bootstrap=debug ./x test library/core
bootstrap::core::build_steps::test::Crate::make_run{}
  DEBUG bootstrap::core::build_steps::test crates=["core"]

[jieyouxu]

I'll have to think about this a bit. Crate is a iffy step that's doing way too many things at once.

[jieyouxu]

In a sense, what I'm trying to say that while ./x test library/core only testing library/core seems Technically Correct, it's not ideal because it feels like it should also run coretests...

[bjorn3]

Once #136642 lands it should work again. The last commit in that PR replaces core with coretests and alloc with alloctests before calling cargo test.

[RalfJung]

Does ./x test core then only execute coretests, or does it still also execute the doctests in libcore?