Re: [PATCH v3 2/3] rust: macros: add macro to easily run KUnit tests

On Wed, Oct 30, 2024 at 12:57:14PM +0800, David Gow wrote:

From: José Expósito jose.exposito89@gmail.com 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 davidgow@google.com Signed-off-by: José Expósito jose.exposito89@gmail.com [Updated to use new const fn.] Signed-off-by: David Gow davidgow@google.com

---

Changes since v2: https://lore.kernel.org/linux-kselftest/20241029092422.2884505-3-davidgow@go...

• 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 | 153 +++++++++++++++++++++++++++++++++++++++++++ rust/macros/lib.rs | 29 ++++++++ 4 files changed, 194 insertions(+) create mode 100644 rust/macros/kunit.rs

diff --git a/MAINTAINERS b/MAINTAINERS index b77f4495dcf4..b65035ede675 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -12433,6 +12433,7 @@ 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/ diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 27bc4139d352..ac296467a552 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -40,6 +40,8 @@ pub fn info(args: fmt::Arguments<'_>) { } } +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. @@ -269,3 +271,12 @@ macro_rules! kunit_unsafe_test_suite { }; }; }

+#[kunit_tests(rust_kernel_kunit)] +mod tests {

• #[test]
• fn rust_test_kunit_kunit_tests() {

•    let running = true;
  

•    assert_eq!(running, true);
  

• }

+} diff --git a/rust/macros/kunit.rs b/rust/macros/kunit.rs new file mode 100644 index 000000000000..850d268cc96a --- /dev/null +++ b/rust/macros/kunit.rs @@ -0,0 +1,153 @@ +// SPDX-License-Identifier: GPL-2.0

+//! Procedural macro to run KUnit tests using a user-space like syntax. +//! +//! Copyright (c) 2023 José Expósito jose.exposito89@gmail.com

+use proc_macro::{Delimiter, Group, TokenStream, TokenTree}; +use std::fmt::Write;

+pub(crate) fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream {

• if attr.to_string().is_empty() {

•    panic!("Missing test name in #[kunit_tests(test_name)] macro")
  

• }
• if attr.to_string().as_bytes().len() > 255 {

•    panic!("The test suite name `{}` exceeds the maximum length of 255 bytes.", attr)
  

• }
• let mut tokens: Vec<_> = ts.into_iter().collect();
• // Scan for the "mod" keyword.
• tokens

•    .iter()
  

•    .find_map(|token| match token {
  

•        TokenTree::Ident(ident) => match ident.to_string().as_str() {
  

•            "mod" => Some(true),
  

•            _ => None,
  

•        },
  

•        _ => None,
  

•    })
  

•    .expect("#[kunit_tests(test_name)] attribute should only be applied to modules");
  

• // Retrieve the main body. The main body should be the last token tree.
• let body = match tokens.pop() {

•    Some(TokenTree::Group(group)) if group.delimiter() == Delimiter::Brace => group,
  

•    _ => panic!("cannot locate main body of module"),
  

• };
• // Get the functions set as tests. Search for `[test]` -> `fn`.
• let mut body_it = body.stream().into_iter();
• let mut tests = Vec::new();
• while let Some(token) = body_it.next() {

•    match token {
  

•        TokenTree::Group(ident) if ident.to_string() == "[test]" => match body_it.next() {
  

•            Some(TokenTree::Ident(ident)) if ident.to_string() == "fn" => {
  

•                let test_name = match body_it.next() {
  

•                    Some(TokenTree::Ident(ident)) => ident.to_string(),
  

•                    _ => continue,
  

•                };
  

•                tests.push(test_name);
  

•            }
  

•            _ => continue,
  

•        },
  

•        _ => (),
  

•    }
  

• }
• // Add `#[cfg(CONFIG_KUNIT)]` before the module declaration.
• let config_kunit = "#[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::bindings::kunit) {
• // foo();
• // }
• // static mut KUNIT_CASE_FOO: kernel::bindings::kunit_case =
• // kernel::kunit::kunit_case(foo, kunit_rust_wrapper_foo);
• //
• // unsafe extern "C" fn kunit_rust_wrapper_bar(_test: * mut kernel::bindings::kunit) {
• // bar();
• // }
• // static mut KUNIT_CASE_BAR: kernel::bindings::kunit_case =
• // kernel::kunit::kunit_case(bar, kunit_rust_wrapper_bar);
• //
• // static mut KUNIT_CASE_NULL: kernel::bindings::kunit_case = kernel::kunit::kunit_case_null();
• //
• // static mut TEST_CASES : &mut[kernel::bindings::kunit_case] = unsafe {
• // &mut [KUNIT_CASE_FOO, KUNIT_CASE_BAR, KUNIT_CASE_NULL]
• // };
• //
• // kernel::kunit_unsafe_test_suite!(kunit_test_suit_name, TEST_CASES);
• // ```
• let mut kunit_macros = "".to_owned();
• let mut test_cases = "".to_owned();
• for test in tests {

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

•    let kunit_case_name = format!("KUNIT_CASE_{}", test.to_uppercase());
  

•    let kunit_wrapper = format!(
  

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

•        kunit_wrapper_fn_name, test
  

•    );
  

•    let kunit_case = format!(
  

•        "static mut {}: kernel::bindings::kunit_case = kernel::kunit::kunit_case(kernel::c_str!(\"{}\"), {});",
  

•        kunit_case_name, test, kunit_wrapper_fn_name
  

•    );
  

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

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

•    writeln!(test_cases, "{kunit_case_name},").unwrap();
  

• }
• writeln!(

•    kunit_macros,
  

•    "static mut KUNIT_CASE_NULL: kernel::bindings::kunit_case = kernel::kunit::kunit_case_null();"
  

• )
• .unwrap();
• writeln!(

•    kunit_macros,
  

•    "static mut TEST_CASES : &mut[kernel::bindings::kunit_case] = unsafe {{ &mut[{test_cases} KUNIT_CASE_NULL] }};"
  

• )
• .unwrap();
• writeln!(

•    kunit_macros,
  

•    "kernel::kunit_unsafe_test_suite!({attr}, TEST_CASES);"
  

• )
• .unwrap();
• let new_body: TokenStream = vec![body.stream(), kunit_macros.parse().unwrap()]

•    .into_iter()
  

•    .collect();
  

• // Remove the `#[test]` macros.
• let new_body = new_body.to_string().replace("#[test]", "");

Yeah, I want to see how you do it this time ;-) So if you do a `.to_string()` on a `TokenStream`, you lose all the span [1] information ("span information" is a term invited by me, hope I get it right ;-)) e.g. if there is a compile error in the test code, the compiler cannot report the exact line of the error, it can only report there is an error.

Last time I find how to preserve the Span:

https://lore.kernel.org/rust-for-linux/ZMba0_XXZuTgWyWY@boqun-archlinux/

Hope it helps!

[1]: https://doc.rust-lang.org/proc_macro/struct.Span.html

Regards, Boqun

• tokens.push(TokenTree::Group(Group::new(

•    Delimiter::Brace,
  

•    new_body.parse().unwrap(),
  

• )));
• tokens.into_iter().collect()

+} diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index 939ae00b723a..098925b99982 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; @@ -430,3 +431,31 @@ 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 like syntax. +/// +/// This macro should be used on modules. If `CONFIG_KUNIT` (in `.config`) is `n`, the target module +/// is ignored. +/// +/// # Examples +/// +/// ```ignore +/// # use macros::kunit_tests; +/// +/// #[kunit_tests(kunit_test_suit_name)] +/// mod tests { +/// #[test] +/// fn foo() { +/// assert_eq!(1, 1); +/// } +/// +/// #[test] +/// fn bar() { +/// assert_eq!(2, 2); +/// } +/// } +/// ``` +#[proc_macro_attribute] +pub fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream {

• kunit::kunit_tests(attr, ts)

+}

2.47.0.163.g1226f6d8fa-goog