Commit 950b306c authored by Miguel Ojeda's avatar Miguel Ojeda
Browse files

rust: kunit: support checked `-> Result`s in KUnit `#[test]`s 



Currently, return values of KUnit `#[test]` functions are ignored.

Thus introduce support for `-> Result` functions by checking their
returned values.

At the same time, require that test functions return `()` or `Result<T,
E>`, which should avoid mistakes, especially with non-`#[must_use]`
types. Other types can be supported in the future if needed.

With this, a failing test like:

    #[test]
    fn my_test() -> Result {
        f()?;
        Ok(())
    }

will output:

    [    3.744214]     KTAP version 1
    [    3.744287]     # Subtest: my_test_suite
    [    3.744378]     # speed: normal
    [    3.744399]     1..1
    [    3.745817]     # my_test: ASSERTION FAILED at rust/kernel/lib.rs:321
    [    3.745817]     Expected is_test_result_ok(my_test()) to be true, but is false
    [    3.747152]     # my_test.speed: normal
    [    3.747199]     not ok 1 my_test
    [    3.747345] not ok 4 my_test_suite

Reviewed-by: default avatarDavid Gow <davidgow@google.com>
Acked-by: default avatarDanilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250502215133.1923676-3-ojeda@kernel.org


[ Used `::kernel` for paths. - Miguel ]
Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent 36174d16

rust/kernel/kunit.rs

+25 −0
Original line number Diff line number Diff line
@@ -164,6 +164,31 @@ macro_rules! kunit_assert_eq { 
    }};

}



trait TestResult {

    fn is_test_result_ok(&self) -> bool;

}



impl TestResult for () {

    fn is_test_result_ok(&self) -> bool {

        true

    }

}



impl<T, E> TestResult for Result<T, E> {

    fn is_test_result_ok(&self) -> bool {

        self.is_ok()

    }

}



/// Returns whether a test result is to be considered OK.

///

/// This will be `assert!`ed from the generated tests.

#[doc(hidden)]

#[expect(private_bounds)]

pub fn is_test_result_ok(t: impl TestResult) -> bool {

    t.is_test_result_ok()

}



/// Represents an individual test case.

///

/// The [`kunit_unsafe_test_suite!`] macro expects a NULL-terminated list of valid test cases.

rust/macros/kunit.rs

+2 −1
Original line number Diff line number Diff line
@@ -102,8 +102,9 @@ pub(crate) fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream { 
    let path = crate::helpers::file();

    for test in &tests {

        let kunit_wrapper_fn_name = format!("kunit_rust_wrapper_{test}");

        // An extra `use` is used here to reduce the length of the message.

        let kunit_wrapper = format!(

            "unsafe extern \"C\" fn {kunit_wrapper_fn_name}(_test: *mut ::kernel::bindings::kunit) {{ {test}(); }}"

            "unsafe extern \"C\" fn {kunit_wrapper_fn_name}(_test: *mut ::kernel::bindings::kunit) {{ use ::kernel::kunit::is_test_result_ok; assert!(is_test_result_ok({test}())); }}",

        );

        writeln!(kunit_macros, "{kunit_wrapper}").unwrap();

        writeln!(