Commit 36174d16 authored by Miguel Ojeda's avatar Miguel Ojeda
Browse files

rust: kunit: support KUnit-mapped `assert!` macros in `#[test]`s 

The KUnit `#[test]` support that landed recently is very basic and does
not map the `assert*!` macros into KUnit like the doctests do, so they
panic at the moment.

Thus implement the custom mapping in a similar way to doctests, reusing
the infrastructure there.

In Rust 1.88.0, the `file()` method in `Span` may be stable [1]. However,
it was changed recently (from `SourceFile`), so we need to do something
different in previous versions. Thus create a helper for it and use it
to get the path.

With this, a failing test suite like:

    #[kunit_tests(my_test_suite)]
    mod tests {
        use super::*;

        #[test]
        fn my_first_test() {
            assert_eq!(42, 43);
        }

        #[test]
        fn my_second_test() {
            assert!(42 >= 43);
        }
    }

will properly map back to KUnit, printing something like:

    [    1.924325]     KTAP version 1
    [    1.924421]     # Subtest: my_test_suite
    [    1.924506]     # speed: normal
    [    1.924525]     1..2
    [    1.926385]     # my_first_test: ASSERTION FAILED at rust/kernel/lib.rs:251
    [    1.926385]     Expected 42 == 43 to be true, but is false
    [    1.928026]     # my_first_test.speed: normal
    [    1.928075]     not ok 1 my_first_test
    [    1.928723]     # my_second_test: ASSERTION FAILED at rust/kernel/lib.rs:256
    [    1.928723]     Expected 42 >= 43 to be true, but is false
    [    1.929834]     # my_second_test.speed: normal
    [    1.929868]     not ok 2 my_second_test
    [    1.930032] # my_test_suite: pass:0 fail:2 skip:0 total:2
    [    1.930153] # Totals: pass:0 fail:2 skip:0 total

Link: https://github.com/rust-lang/rust/pull/140514

 [1]
Reviewed-by: default avatarDavid Gow <davidgow@google.com>
Acked-by: default avatarDanilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250502215133.1923676-2-ojeda@kernel.org


[ Required `KUNIT=y` like for doctests. Used the `cfg_attr` from the
  TODO comment and clarified its comment now that the stabilization is
  in beta and thus quite likely stable in Rust 1.88.0. Simplified the
  `new_body` code by introducing a new variable. Added
  `#[allow(clippy::incompatible_msrv)]`. - Miguel ]
Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent 4bf7b97e

init/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -140,6 +140,9 @@ config LD_CAN_USE_KEEP_IN_OVERLAY 
config RUSTC_HAS_COERCE_POINTEE

	def_bool RUSTC_VERSION >= 108400



config RUSTC_HAS_SPAN_FILE

	def_bool RUSTC_VERSION >= 108800



config RUSTC_HAS_UNNECESSARY_TRANSMUTES

	def_bool RUSTC_VERSION >= 108800

rust/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -404,7 +404,8 @@ quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@ 
		-Clink-args='$(call escsq,$(KBUILD_PROCMACROLDFLAGS))' \

		--emit=dep-info=$(depfile) --emit=link=$@ --extern proc_macro \

		--crate-type proc-macro \

		--crate-name $(patsubst lib%.$(libmacros_extension),%,$(notdir $@)) $<

		--crate-name $(patsubst lib%.$(libmacros_extension),%,$(notdir $@)) \

		@$(objtree)/include/generated/rustc_cfg $<



# Procedural macros can only be used with the `rustc` that compiled it.

$(obj)/$(libmacros_name): $(src)/macros/lib.rs FORCE

rust/kernel/kunit.rs

+0 −1
Original line number Diff line number Diff line
@@ -323,7 +323,6 @@ mod tests { 


    #[test]

    fn rust_test_kunit_example_test() {

        #![expect(clippy::eq_op)]

        assert_eq!(1 + 1, 2);

    }

rust/macros/helpers.rs

+17 −0
Original line number Diff line number Diff line
@@ -86,3 +86,20 @@ pub(crate) fn function_name(input: TokenStream) -> Option<Ident> { 
    }

    None

}



pub(crate) fn file() -> String {

    #[cfg(not(CONFIG_RUSTC_HAS_SPAN_FILE))]

    {

        proc_macro::Span::call_site()

            .source_file()

            .path()

            .to_string_lossy()

            .into_owned()

    }



    #[cfg(CONFIG_RUSTC_HAS_SPAN_FILE)]

    #[allow(clippy::incompatible_msrv)]

    {

        proc_macro::Span::call_site().file()

    }

}

rust/macros/kunit.rs

+30 −5
Original line number Diff line number Diff line
@@ -57,8 +57,8 @@ pub(crate) fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream { 
        }

    }



    // Add `#[cfg(CONFIG_KUNIT)]` before the module declaration.

    let config_kunit = "#[cfg(CONFIG_KUNIT)]".to_owned().parse().unwrap();

    // Add `#[cfg(CONFIG_KUNIT="y")]` before the module declaration.

    let config_kunit = "#[cfg(CONFIG_KUNIT=\"y\")]".to_owned().parse().unwrap();

    tokens.insert(

        0,

        TokenTree::Group(Group::new(Delimiter::None, config_kunit)),
@@ -98,6 +98,8 @@ pub(crate) fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream { 
    // ```

    let mut kunit_macros = "".to_owned();

    let mut test_cases = "".to_owned();

    let mut assert_macros = "".to_owned();

    let path = crate::helpers::file();

    for test in &tests {

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

        let kunit_wrapper = format!(
@@ -109,6 +111,27 @@ pub(crate) fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream { 
            "    ::kernel::kunit::kunit_case(::kernel::c_str!(\"{test}\"), {kunit_wrapper_fn_name}),"

        )

        .unwrap();

        writeln!(

            assert_macros,

            r#"

/// Overrides the usual [`assert!`] macro with one that calls KUnit instead.

#[allow(unused)]

macro_rules! assert {{

    ($cond:expr $(,)?) => {{{{

        kernel::kunit_assert!("{test}", "{path}", 0, $cond);

    }}}}

}}



/// Overrides the usual [`assert_eq!`] macro with one that calls KUnit instead.

#[allow(unused)]

macro_rules! assert_eq {{

    ($left:expr, $right:expr $(,)?) => {{{{

        kernel::kunit_assert_eq!("{test}", "{path}", 0, $left, $right);

    }}}}

}}

        "#

        )

        .unwrap();

    }



    writeln!(kunit_macros).unwrap();
@@ -147,10 +170,12 @@ pub(crate) fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream { 
        }

    }



    let mut new_body = TokenStream::from_iter(new_body);

    new_body.extend::<TokenStream>(kunit_macros.parse().unwrap());

    let mut final_body = TokenStream::new();

    final_body.extend::<TokenStream>(assert_macros.parse().unwrap());

    final_body.extend(new_body);

    final_body.extend::<TokenStream>(kunit_macros.parse().unwrap());



    tokens.push(TokenTree::Group(Group::new(Delimiter::Brace, new_body)));

    tokens.push(TokenTree::Group(Group::new(Delimiter::Brace, final_body)));



    tokens.into_iter().collect()

}