Re: [PATCH 2/7] rust: kunit: support checked `-> Result`s in KUnit `#[test]`s

[David Gow <davidgow@google.com>]

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On Mon, 5 May 2025 at 02:00, Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Sun, May 4, 2025 at 7:34 PM Tamir Duberstein <tamird@gmail.com> wrote:
> >
> > Why not restrict this to Result<(), E>?
>
> I guess it is an option -- not sure if there may be a use case.
>
> > Is it possible to include the error in the output?
>
> I thought about giving some more context somehow and perhaps printing
> it "manually" in the log, possibly in a KUnit `# ...`. David can
> probably suggest the "proper" way.

Yeah, writing it to the log is fine: probably the best way of handling
this would be to have a kunit assertion macro for "assert_is_ok!()",
which prints the error nicely.
We could just use the existing kernel::kunit::err() function (which
could use some improvement, but is a good start), or even add a proper
assertion formatter which handles rust types via %pA.

That being said, there's no guarantee that the Err branch of a
Result<> can be printed: so there'd need to be some magic to handle
both the case where (e.g.) Err derives Debug, and the case where it
doesn't (in which case, we're basically stuck with what we've got
here: "expected is_ok()" or similar.

Cheers,
-- David

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