Re: [PATCH 0/3] rust: kunit: support #[should_panic] and same test name with different #[cfg(...)]

["Gary Guo" <gary@garyguo.net>]

On Wed Sep 30, 2026 at 2:23 PM BST, Nicolás Antinori via B4 Relay wrote:
> This patch series intends to implement two features for KUnit tests
> written in Rust. The work is based on a TODO comment made in the
> `bitmap.rs` module [1].
>
> Changelog:
> - RFC patch: [3]
>
> 1. Supporting `#[should_panic]` [2]:
>
> KUnit tests in Rust follow the user-space syntax, but at the moment
> `#[should_panic]` is not supported. The first patch of this series adds
> support for the attribute (only in its basic form, `#[should_panic =
> "message"]` is not supported yet).
>
> The way it is supported is by adding a new boolean property called
> `rust_should_panic` to `kunit_attributes` struct in kunit/test.h and

This is now more general than Rust panics? Perhaps this should just be
"should_bug"?

Best,
Gary


> check for the `try_catch->try_result` code and the named flag to detect
> if there was a panic in `lib/kunit/test.c::kunit_run_case_catch_errors`
> function.
>
> The difference with the previous version [3] is that now, almost
> everything is handled in the C side, meaning that we don't have a
> separate `#[panic_handler]` when KUnit tests are active. In other words
> there's no need of a Rust side panic handler because the C side catches
> Rust's panics too, since the `#[panic_hanlder]` executes a
> bindings::BUG().
>
> 2. Allow same test name with different #[cfg(...)]:
>
> When testing `#[should_panic]` in `bitmap.rs` (check the last patch of
> the series) I found that the test that was supposed to panic had the
> same name as another one, but they were run on different configurations.
> This caused the following compilation error:
>
> ERROR:root:error[E0428]: the name `kunit_rust_wrapper_owned_bitmap_out_of_bounds` is defined multiple times
>    --> ../rust/kernel/bitmap.rs:503:1
>     |
> 503 | #[macros::kunit_tests(rust_kernel_bitmap)]
>     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `kunit_rust_wrapper_owned_bitmap_out_of_bounds` redefined here
>     |
>     = note: `kunit_rust_wrapper_owned_bitmap_out_of_bounds` must be defined only once in the value namespace of this module
>     = note: this error originates in the attribute macro `macros::kunit_tests` (in Nightly builds, run with -Z macro-backtrace for more info)
>
> Now, only the tests with an active `#[cfg(...)]` will be executed by the
> runner. Tests with an inactive `#[cfg(...)]` will not appear in the
> report since they are not added to the TEST_CASES array.
>
> [1] https://github.com/Rust-for-Linux/linux/blob/fd73f4a6659897191fa0d40695fe370925dd3780/rust/kernel/bitmap.rs#L592-L600
> [2] https://doc.rust-lang.org/rust-by-example/testing/unit_testing.html#testing-panics
> [3] https://lore.kernel.org/rust-for-linux/cover.1789500084.git.nico.antinori.7@gmail.com/
>
> Signed-off-by: Nicolás Antinori <nico.antinori.7@gmail.com>
> ---
> Nicolás Antinori (3):
>       rust: kunit: add #[should_panic] support
>       rust: kunit: allow same test name with different #[cfg(...)]
>       rust: bitmap: kunit: uncomment owned_bitmap_out_of_bounds panic case
>
>  include/kunit/test.h   |  1 +
>  lib/kunit/attributes.c | 18 ++++++++++++++++++
>  lib/kunit/test.c       |  5 +++++
>  rust/kernel/bitmap.rs  | 40 ++++++++++++++++++----------------------
>  rust/kernel/kunit.rs   | 37 +++++++++++++++++++++++++++++++++++++
>  rust/macros/kunit.rs   | 48 ++++++++++++++++++++++++++++++++++++++----------
>  6 files changed, 117 insertions(+), 32 deletions(-)
> ---
> base-commit: d266640c6c760c9bc215bf5a3ece122ca488b6f5
> change-id: 20260930-rust_kunit_v4-7abaee11e6ac
>
> Best regards,