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charset="utf-8" From: Jos=C3=A9 Exp=C3=B3sito Add a couple of Rust const functions and macros to allow to develop KUnit tests without relying on generated C code: - The `kunit_unsafe_test_suite!` Rust macro is similar to the `kunit_test_suite` C macro. It requires a NULL-terminated array of test cases (see below). - The `kunit_case` Rust function is similar to the `KUNIT_CASE` C macro. It generates as case from the name and function. - The `kunit_case_null` Rust function generates a NULL test case, which is to be used as delimiter in `kunit_test_suite!`. While these functions and macros can be used on their own, a future patch will introduce=C2=A0another macro to create KUnit tests using a user-space like syntax. Signed-off-by: Jos=C3=A9 Exp=C3=B3sito Co-developed-by: Matt Gilbride Signed-off-by: Matt Gilbride Co-developed-by: Miguel Ojeda Signed-off-by: Miguel Ojeda Co-developed-by: David Gow Signed-off-by: David Gow --- Changes since v7: https://lore.kernel.org/rust-for-linux/20250214074051.1619256-2-davidgow@go= ogle.com/ - Reworked the SAFETY comment for addr_of_mut! use with statics in kunit_unsafe_test_suite!() (again). - Equally, updated the macro documentation to make the safety precondition (that $test_cases should be static) clearer. Changes since v6: https://lore.kernel.org/rust-for-linux/20250214074051.1619256-2-davidgow@go= ogle.com/ - Fixed an [allow(unused_unsafe)] which ended up in patch 2 instead of patch 1. (Thanks, Tamir!) - Doc comments now have several useful links. (Thanks, Tamir!) - Fix a potential compile error under macos. (Thanks, Tamir!) - Several small tidy-ups to limit unsafe usage. (Thanks, Tamir!) Changes since v5: https://lore.kernel.org/all/20241213081035.2069066-2-davidgow@google.com/ - Rebased against 6.14-rc1 - Several documentation touch-ups, including noting that the example test function need not be unsafe. (Thanks, Miguel) - Remove the need for static_mut_refs, by using core::addr_of_mut!() combined with a cast. (Thanks, Miguel) - While this should also avoid the need for const_mut_refs, it seems to have been enabled for other users anyway. - Use ::kernel::ffi::c_char for C strings, rather than i8 directly. (Thanks, Miguel) Changes since v4: https://lore.kernel.org/linux-kselftest/20241101064505.3820737-2-davidgow@g= oogle.com/ - Rebased against 6.13-rc1 - Allowed an unused_unsafe warning after the behaviour of addr_of_mut!() changed in Rust 1.82. (Thanks Boqun, Miguel) - Fix a couple of minor rustfmt issues which were triggering checkpatch warnings. Changes since v3: https://lore.kernel.org/linux-kselftest/20241030045719.3085147-4-davidgow@g= oogle.com/ - The kunit_unsafe_test_suite!() macro now panic!s if the suite name is too long, triggering a compile error. (Thanks, Alice!) Changes since v2: https://lore.kernel.org/linux-kselftest/20241029092422.2884505-2-davidgow@g= oogle.com/ - The kunit_unsafe_test_suite!() macro will truncate the name of the suite if it is too long. (Thanks Alice!) - We no longer needlessly use UnsafeCell<> in kunit_unsafe_test_suite!(). (Thanks Alice!) Changes since v1: https://lore.kernel.org/lkml/20230720-rustbind-v1-1-c80db349e3b5@google.com/ - Rebase on top of rust-next - As a result, KUnit attributes are new set. These are hardcoded to the defaults of "normal" speed and no module name. - Split the kunit_case!() macro into two const functions, kunit_case() and kunit_case_null() (for the NULL terminator). --- Changes since v6: https://lore.kernel.org/rust-for-linux/20250214074051.1619256-2-davidgow@go= ogle.com/ - Fixed an [allow(unused_unsafe)] which ended up in patch 2 instead of patch 1. (Thanks, Tamir!) - Doc comments now have several useful links. (Thanks, Tamir!) - Fix a potential compile error under macos. (Thanks, Tamir!) - Several small tidy-ups to limit unsafe usage. (Thanks, Tamir!) Changes since v5: https://lore.kernel.org/all/20241213081035.2069066-2-davidgow@google.com/ - Rebased against 6.14-rc1 - Several documentation touch-ups, including noting that the example test function need not be unsafe. (Thanks, Miguel) - Remove the need for static_mut_refs, by using core::addr_of_mut!() combined with a cast. (Thanks, Miguel) - While this should also avoid the need for const_mut_refs, it seems to have been enabled for other users anyway. - Use ::kernel::ffi::c_char for C strings, rather than i8 directly. (Thanks, Miguel) Changes since v4: https://lore.kernel.org/linux-kselftest/20241101064505.3820737-2-davidgow@g= oogle.com/ - Rebased against 6.13-rc1 - Allowed an unused_unsafe warning after the behaviour of addr_of_mut!() changed in Rust 1.82. (Thanks Boqun, Miguel) - Fix a couple of minor rustfmt issues which were triggering checkpatch warnings. Changes since v3: https://lore.kernel.org/linux-kselftest/20241030045719.3085147-4-davidgow@g= oogle.com/ - The kunit_unsafe_test_suite!() macro now panic!s if the suite name is too long, triggering a compile error. (Thanks, Alice!) Changes since v2: https://lore.kernel.org/linux-kselftest/20241029092422.2884505-2-davidgow@g= oogle.com/ - The kunit_unsafe_test_suite!() macro will truncate the name of the suite if it is too long. (Thanks Alice!) - We no longer needlessly use UnsafeCell<> in kunit_unsafe_test_suite!(). (Thanks Alice!) Changes since v1: https://lore.kernel.org/lkml/20230720-rustbind-v1-1-c80db349e3b5@google.com/ - Rebase on top of rust-next - As a result, KUnit attributes are new set. These are hardcoded to the defaults of "normal" speed and no module name. - Split the kunit_case!() macro into two const functions, kunit_case() and kunit_case_null() (for the NULL terminator). --- rust/kernel/kunit.rs | 124 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 824da0e9738a..1b9b52892562 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -161,3 +161,127 @@ macro_rules! kunit_assert_eq { $crate::kunit_assert!($name, $file, $diff, $left =3D=3D $right); }}; } + +/// Represents an individual test case. +/// +/// The [`kunit_unsafe_test_suite!`] macro expects a NULL-terminated list = of valid test cases. +/// Use [`kunit_case_null`] to generate such a delimiter. +#[doc(hidden)] +pub const fn kunit_case( + name: &'static kernel::str::CStr, + run_case: unsafe extern "C" fn(*mut kernel::bindings::kunit), +) -> kernel::bindings::kunit_case { + kernel::bindings::kunit_case { + run_case: Some(run_case), + name: name.as_char_ptr(), + attr: kernel::bindings::kunit_attributes { + speed: kernel::bindings::kunit_speed_KUNIT_SPEED_NORMAL, + }, + generate_params: None, + status: kernel::bindings::kunit_status_KUNIT_SUCCESS, + module_name: core::ptr::null_mut(), + log: core::ptr::null_mut(), + } +} + +/// Represents the NULL test case delimiter. +/// +/// The [`kunit_unsafe_test_suite!`] macro expects a NULL-terminated list = of test cases. This +/// function returns such a delimiter. +#[doc(hidden)] +pub const fn kunit_case_null() -> kernel::bindings::kunit_case { + kernel::bindings::kunit_case { + run_case: None, + name: core::ptr::null_mut(), + generate_params: None, + attr: kernel::bindings::kunit_attributes { + speed: kernel::bindings::kunit_speed_KUNIT_SPEED_NORMAL, + }, + status: kernel::bindings::kunit_status_KUNIT_SUCCESS, + module_name: core::ptr::null_mut(), + log: core::ptr::null_mut(), + } +} + +/// Registers a KUnit test suite. +/// +/// # Safety +/// +/// `test_cases` must be a NULL terminated array of valid test cases, +/// whose lifetime is at least that of the test suite (i.e., static). +/// +/// # Examples +/// +/// ```ignore +/// extern "C" fn test_fn(_test: *mut kernel::bindings::kunit) { +/// let actual =3D 1 + 1; +/// let expected =3D 2; +/// assert_eq!(actual, expected); +/// } +/// +/// static mut KUNIT_TEST_CASES: [kernel::bindings::kunit_case; 2] =3D [ +/// kernel::kunit::kunit_case(kernel::c_str!("name"), test_fn), +/// kernel::kunit::kunit_case_null(), +/// ]; +/// kernel::kunit_unsafe_test_suite!(suite_name, KUNIT_TEST_CASES); +/// ``` +#[doc(hidden)] +#[macro_export] +macro_rules! kunit_unsafe_test_suite { + ($name:ident, $test_cases:ident) =3D> { + const _: () =3D { + const KUNIT_TEST_SUITE_NAME: [::kernel::ffi::c_char; 256] =3D { + let name_u8 =3D ::core::stringify!($name).as_bytes(); + let mut ret =3D [0; 256]; + + if name_u8.len() > 255 { + panic!(concat!( + "The test suite name `", + ::core::stringify!($name), + "` exceeds the maximum length of 255 bytes." + )); + } + + let mut i =3D 0; + while i < name_u8.len() { + ret[i] =3D name_u8[i] as ::kernel::ffi::c_char; + i +=3D 1; + } + + ret + }; + + static mut KUNIT_TEST_SUITE: ::kernel::bindings::kunit_suite = =3D + ::kernel::bindings::kunit_suite { + name: KUNIT_TEST_SUITE_NAME, + #[allow(unused_unsafe)] + // SAFETY: $test_cases is passed in by the user, and + // (as documented) must be valid for the lifetime of + // the suite (i.e., static). + test_cases: unsafe { + ::core::ptr::addr_of_mut!($test_cases) + .cast::<::kernel::bindings::kunit_case>() + }, + suite_init: None, + suite_exit: None, + init: None, + exit: None, + attr: ::kernel::bindings::kunit_attributes { + speed: ::kernel::bindings::kunit_speed_KUNIT_SPEED= _NORMAL, + }, + status_comment: [0; 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Fri, 07 Mar 2025 01:05:03 -0800 (PST) Date: Fri, 7 Mar 2025 17:00:57 +0800 In-Reply-To: <20250307090103.918788-1-davidgow@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250307090103.918788-1-davidgow@google.com> X-Mailer: git-send-email 2.49.0.rc0.332.g42c0ae87b1-goog Message-ID: <20250307090103.918788-3-davidgow@google.com> Subject: [PATCH v8 2/3] rust: macros: add macro to easily run KUnit tests From: David Gow To: Miguel Ojeda , "=?UTF-8?q?Jos=C3=A9=20Exp=C3=B3sito?=" , Rae Moar , Boqun Feng , Alex Gaynor , Gary Guo , Benno Lossin , "=?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?=" , Alice Ryhl , Matt Gilbride , Brendan Higgins , Tamir Duberstein Cc: kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, David Gow Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Jos=C3=A9 Exp=C3=B3sito Add a new procedural macro (`#[kunit_tests(kunit_test_suit_name)]`) to run KUnit tests using a user-space like syntax. The macro, that should be used on modules, transforms every `#[test]` in a `kunit_case!` and adds a `kunit_unsafe_test_suite!` registering all of them. The only difference with user-space tests is that instead of using `#[cfg(test)]`, `#[kunit_tests(kunit_test_suit_name)]` is used. Note that `#[cfg(CONFIG_KUNIT)]` is added so the test module is not compiled when `CONFIG_KUNIT` is set to `n`. Reviewed-by: David Gow Signed-off-by: Jos=C3=A9 Exp=C3=B3sito Co-developed-by: Boqun Feng Signed-off-by: Boqun Feng Co-developed-by: Miguel Ojeda Signed-off-by: Miguel Ojeda Reviewed-by: Tamir Duberstein Signed-off-by: David Gow --- No changes since v7: https://lore.kernel.org/rust-for-linux/20250214074051.1619256-3-davidgow@go= ogle.com/ Changes since v6: https://lore.kernel.org/rust-for-linux/20250214074051.1619256-3-davidgow@go= ogle.com/ - Fixed an [allow(unused_unsafe)] which ended up in patch 2 instead of patch 1. (Thanks, Tamir!) - Add Tamir's Reviewed-by tag. Changes since v5: https://lore.kernel.org/all/20241213081035.2069066-3-davidgow@google.com/ - Fix some rustfmt-related formatting shenanigans. (Thanks, Miguel) - Fix some documentation comment formatting as well. (Thanks, Miguel) - Tidy up the generated code to avoid unneeded &mut[] everywhere. (Thanks, Miguel) - Fix a new clippy warning for using .as_bytes().len() instead of .len() directly. Changes since v4: https://lore.kernel.org/linux-kselftest/20241101064505.3820737-3-davidgow@g= oogle.com/ - Rebased against 6.13-rc1 - "Expect" that the sample assert_eq!(1+1, 2) produces a clippy warning due to a redundant assertion. (Thanks Boqun, Miguel) Changes since v3: https://lore.kernel.org/linux-kselftest/20241030045719.3085147-6-davidgow@g= oogle.com/ - The #[kunit_tests()] macro now preserves span information, so errors can be better reported. (Thanks, Boqun!) - The example test has been replaced to no longer use assert_eq!() with a constant bool argument (which triggered a clippy warning now we have the span info). It now checks 1 + 1 =3D=3D 2, to match the C example. - (The in_kunit_test() test in the next patch uses assert!() to check a bool, so having something different here seemed to make a better example.) Changes since v2: https://lore.kernel.org/linux-kselftest/20241029092422.2884505-3-davidgow@g= oogle.com/ - Include missing rust/macros/kunit.rs file from v2. (Thanks Boqun!) - The proc macro now emits an error if the suite name is too long. Changes since v1: https://lore.kernel.org/lkml/20230720-rustbind-v1-2-c80db349e3b5@google.com/ - Rebased on top of rust-next - Make use of the new const functions, rather than the kunit_case!() macro. --- MAINTAINERS | 1 + rust/kernel/kunit.rs | 11 +++ rust/macros/kunit.rs | 161 +++++++++++++++++++++++++++++++++++++++++++ rust/macros/lib.rs | 29 ++++++++ 4 files changed, 202 insertions(+) create mode 100644 rust/macros/kunit.rs diff --git a/MAINTAINERS b/MAINTAINERS index c8d9e8187eb0..4e7a6d2f2c49 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -12677,6 +12677,7 @@ F: Documentation/dev-tools/kunit/ F: include/kunit/ F: lib/kunit/ F: rust/kernel/kunit.rs +F: rust/macros/kunit.rs F: scripts/rustdoc_test_* F: tools/testing/kunit/ =20 diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 1b9b52892562..97e99b52e4a9 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -40,6 +40,8 @@ pub fn info(args: fmt::Arguments<'_>) { } } =20 +use macros::kunit_tests; + /// Asserts that a boolean expression is `true` at runtime. /// /// Public but hidden since it should only be used from generated tests. @@ -285,3 +287,12 @@ macro_rules! kunit_unsafe_test_suite { }; }; } + +#[kunit_tests(rust_kernel_kunit)] +mod tests { + #[test] + fn rust_test_kunit_example_test() { + #![expect(clippy::eq_op)] + assert_eq!(1 + 1, 2); + } +} diff --git a/rust/macros/kunit.rs b/rust/macros/kunit.rs new file mode 100644 index 000000000000..4f553ecf40c0 --- /dev/null +++ b/rust/macros/kunit.rs @@ -0,0 +1,161 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Procedural macro to run KUnit tests using a user-space like syntax. +//! +//! Copyright (c) 2023 Jos=C3=A9 Exp=C3=B3sito + +use proc_macro::{Delimiter, Group, TokenStream, TokenTree}; +use std::fmt::Write; + +pub(crate) fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStre= am { + let attr =3D attr.to_string(); + + if attr.is_empty() { + panic!("Missing test name in `#[kunit_tests(test_name)]` macro") + } + + if attr.len() > 255 { + panic!( + "The test suite name `{}` exceeds the maximum length of 255 by= tes", + attr + ) + } + + let mut tokens: Vec<_> =3D ts.into_iter().collect(); + + // Scan for the `mod` keyword. + tokens + .iter() + .find_map(|token| match token { + TokenTree::Ident(ident) =3D> match ident.to_string().as_str() { + "mod" =3D> Some(true), + _ =3D> None, + }, + _ =3D> None, + }) + .expect("`#[kunit_tests(test_name)]` attribute should only be appl= ied to modules"); + + // Retrieve the main body. The main body should be the last token tree. + let body =3D match tokens.pop() { + Some(TokenTree::Group(group)) if group.delimiter() =3D=3D Delimite= r::Brace =3D> group, + _ =3D> panic!("Cannot locate main body of module"), + }; + + // Get the functions set as tests. Search for `[test]` -> `fn`. + let mut body_it =3D body.stream().into_iter(); + let mut tests =3D Vec::new(); + while let Some(token) =3D body_it.next() { + match token { + TokenTree::Group(ident) if ident.to_string() =3D=3D "[test]" = =3D> match body_it.next() { + Some(TokenTree::Ident(ident)) if ident.to_string() =3D=3D = "fn" =3D> { + let test_name =3D match body_it.next() { + Some(TokenTree::Ident(ident)) =3D> ident.to_string= (), + _ =3D> continue, + }; + tests.push(test_name); + } + _ =3D> continue, + }, + _ =3D> (), + } + } + + // Add `#[cfg(CONFIG_KUNIT)]` before the module declaration. + let config_kunit =3D "#[cfg(CONFIG_KUNIT)]".to_owned().parse().unwrap(= ); + tokens.insert( + 0, + TokenTree::Group(Group::new(Delimiter::None, config_kunit)), + ); + + // Generate the test KUnit test suite and a test case for each `#[test= ]`. + // The code generated for the following test module: + // + // ``` + // #[kunit_tests(kunit_test_suit_name)] + // mod tests { + // #[test] + // fn foo() { + // assert_eq!(1, 1); + // } + // + // #[test] + // fn bar() { + // assert_eq!(2, 2); + // } + // } + // ``` + // + // Looks like: + // + // ``` + // unsafe extern "C" fn kunit_rust_wrapper_foo(_test: *mut kernel::bin= dings::kunit) { foo(); } + // unsafe extern "C" fn kunit_rust_wrapper_bar(_test: *mut kernel::bin= dings::kunit) { bar(); } + // + // static mut TEST_CASES: [kernel::bindings::kunit_case; 3] =3D [ + // kernel::kunit::kunit_case(kernel::c_str!("foo"), kunit_rust_wra= pper_foo), + // kernel::kunit::kunit_case(kernel::c_str!("bar"), kunit_rust_wra= pper_bar), + // kernel::kunit::kunit_case_null(), + // ]; + // + // kernel::kunit_unsafe_test_suite!(kunit_test_suit_name, TEST_CASES); + // ``` + let mut kunit_macros =3D "".to_owned(); + let mut test_cases =3D "".to_owned(); + for test in &tests { + let kunit_wrapper_fn_name =3D format!("kunit_rust_wrapper_{}", tes= t); + let kunit_wrapper =3D format!( + "unsafe extern \"C\" fn {}(_test: *mut kernel::bindings::kunit= ) {{ {}(); }}", + kunit_wrapper_fn_name, test + ); + writeln!(kunit_macros, "{kunit_wrapper}").unwrap(); + writeln!( + test_cases, + " kernel::kunit::kunit_case(kernel::c_str!(\"{}\"), {}),", + test, kunit_wrapper_fn_name + ) + .unwrap(); + } + + writeln!(kunit_macros).unwrap(); + writeln!( + kunit_macros, + "static mut TEST_CASES: [kernel::bindings::kunit_case; {}] =3D [\n= {test_cases} kernel::kunit::kunit_case_null(),\n];", + tests.len() + 1 + ) + .unwrap(); + + writeln!( + kunit_macros, + "kernel::kunit_unsafe_test_suite!({attr}, TEST_CASES);" + ) + .unwrap(); + + // Remove the `#[test]` macros. + // We do this at a token level, in order to preserve span information. + let mut new_body =3D vec![]; + let mut body_it =3D body.stream().into_iter(); + + while let Some(token) =3D body_it.next() { + match token { + TokenTree::Punct(ref c) if c.as_char() =3D=3D '#' =3D> match b= ody_it.next() { + Some(TokenTree::Group(group)) if group.to_string() =3D=3D = "[test]" =3D> (), + Some(next) =3D> { + new_body.extend([token, next]); + } + _ =3D> { + new_body.push(token); + } + }, + _ =3D> { + new_body.push(token); + } + } + } + + let mut new_body =3D TokenStream::from_iter(new_body); + new_body.extend::(kunit_macros.parse().unwrap()); + + tokens.push(TokenTree::Group(Group::new(Delimiter::Brace, new_body))); + + tokens.into_iter().collect() +} diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index d61bc6a56425..50b58259c577 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -10,6 +10,7 @@ mod quote; mod concat_idents; mod helpers; +mod kunit; mod module; mod paste; mod pin_data; @@ -492,3 +493,31 @@ pub fn paste(input: TokenStream) -> TokenStream { pub fn derive_zeroable(input: TokenStream) -> TokenStream { zeroable::derive(input) } + +/// Registers a KUnit test suite and its test cases using a user-space lik= e syntax. +/// +/// This macro should be used on modules. 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Fri, 07 Mar 2025 01:05:08 -0800 (PST) Date: Fri, 7 Mar 2025 17:00:58 +0800 In-Reply-To: <20250307090103.918788-1-davidgow@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250307090103.918788-1-davidgow@google.com> X-Mailer: git-send-email 2.49.0.rc0.332.g42c0ae87b1-goog Message-ID: <20250307090103.918788-4-davidgow@google.com> Subject: [PATCH v8 3/3] rust: kunit: allow to know if we are in a test From: David Gow To: Miguel Ojeda , "=?UTF-8?q?Jos=C3=A9=20Exp=C3=B3sito?=" , Rae Moar , Boqun Feng , Alex Gaynor , Gary Guo , Benno Lossin , "=?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?=" , Alice Ryhl , Matt Gilbride , Brendan Higgins , Tamir Duberstein Cc: kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, David Gow Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Jos=C3=A9 Exp=C3=B3sito In some cases, we need to call test-only code from outside the test case, for example, to mock a function or a module. In order to check whether we are in a test or not, we need to test if `CONFIG_KUNIT` is set. Unfortunately, we cannot rely only on this condition because: - a test could be running in another thread, - some distros compile KUnit in production kernels, so checking at runtime that `current->kunit_test !=3D NULL` is required. Forturately, KUnit provides an optimised check in `kunit_get_current_test()`, which checks CONFIG_KUNIT, a global static key, and then the current thread's running KUnit test. Add a safe wrapper function around this to know whether or not we are in a KUnit test and examples showing how to mock a function and a module. Signed-off-by: Jos=C3=A9 Exp=C3=B3sito Co-developed-by: Miguel Ojeda Signed-off-by: Miguel Ojeda Co-developed-by: David Gow Signed-off-by: David Gow --- Changes since v7: https://lore.kernel.org/rust-for-linux/20250214074051.1619256-4-davidgow@go= ogle.com/ - Remove the second example, which shadowed a function in order to mock it, as it was (a) unclear that it is only useful for code in the same file as the test, and (b) didn't use in_kunit_test(), which would've made it more useful (but still limited). The first example should be good enough to point people in the right direction for now. (Thanks, Tamir) Changes since v6: https://lore.kernel.org/rust-for-linux/20250214074051.1619256-4-davidgow@go= ogle.com/ - Doc comments now have a useful link. (Thanks, Tamir!) - A small tidy-up to limit unsafe usage. (Thanks, Tamir!) Changes since v5: https://lore.kernel.org/all/20241213081035.2069066-4-davidgow@google.com/ - Greatly improved documentation, which is both clearer and better matches the rustdoc norm. (Thanks, Miguel) - The examples and safety comments are also both more idiomatic an cleaner. (Thanks, Miguel) - More things sit appropriately behind CONFIG_KUNIT (Thanks, Miguel) Changes since v4: https://lore.kernel.org/linux-kselftest/20241101064505.3820737-4-davidgow@g= oogle.com/ - Rebased against 6.13-rc1 - Fix some missing safety comments, and remove some unneeded 'unsafe' blocks. (Thanks Boqun) Changes since v3: https://lore.kernel.org/linux-kselftest/20241030045719.3085147-8-davidgow@g= oogle.com/ - The example test has been updated to no longer use assert_eq!() with a constant bool argument (fixes a clippy warning). No changes since v2: https://lore.kernel.org/linux-kselftest/20241029092422.2884505-4-davidgow@g= oogle.com/ Changes since v1: https://lore.kernel.org/lkml/20230720-rustbind-v1-3-c80db349e3b5@google.com/ - Rebased on top of rust-next. - Use the `kunit_get_current_test()` C function, which wasn't previously available, instead of rolling our own. - (Thanks also to Boqun for suggesting a nicer way of implementing this, which I tried, but the `kunit_get_current_test()` version obsoleted.) --- rust/kernel/kunit.rs | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 97e99b52e4a9..7388fa831b8e 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -288,11 +288,47 @@ macro_rules! kunit_unsafe_test_suite { }; } =20 +/// Returns whether we are currently running a KUnit test. +/// +/// In some cases, you need to call test-only code from outside the test c= ase, for example, to +/// create a function mock. This function allows to change behavior depend= ing on whether we are +/// currently running a KUnit test or not. +/// +/// # Examples +/// +/// This example shows how a function can be mocked to return a well-known= value while testing: +/// +/// ``` +/// # use kernel::kunit::in_kunit_test; +/// fn fn_mock_example(n: i32) -> i32 { +/// if in_kunit_test() { +/// return 100; +/// } +/// +/// n + 1 +/// } +/// +/// let mock_res =3D fn_mock_example(5); +/// assert_eq!(mock_res, 100); +/// ``` +pub fn in_kunit_test() -> bool { + // SAFETY: `kunit_get_current_test()` is always safe to call (it has f= allbacks for + // when KUnit is not enabled). + !unsafe { bindings::kunit_get_current_test() }.is_null() +} + #[kunit_tests(rust_kernel_kunit)] mod tests { + use super::*; + #[test] fn rust_test_kunit_example_test() { #![expect(clippy::eq_op)] assert_eq!(1 + 1, 2); } + + #[test] + fn rust_test_kunit_in_kunit_test() { + assert!(in_kunit_test()); + } } --=20 2.49.0.rc0.332.g42c0ae87b1-goog