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

David Gow
2023-07-20T06:41:12Z

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>
---
MAINTAINERS | 1 +
rust/kernel/kunit.rs | 11 ++++
rust/macros/kunit.rs | 149 +++++++++++++++++++++++++++++++++++++++++++++++++++
rust/macros/lib.rs | 29 ++++++++++
4 files changed, 190 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 2a942fe59144..c32ba6b29a96 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11373,6 +11373,7 @@ 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 4cffc71e463b..44ea67028316 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.
@@ -253,3 +255,12 @@ 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..69dac253232f
--- /dev/null
+++ b/rust/macros/kunit.rs
@@ -0,0 +1,149 @@
+// 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")
+ }
+
+ 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_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_case!(bar, kunit_rust_wrapper_bar);
+ //
+ // static mut KUNIT_CASE_NULL: kernel::bindings::kunit_case = kernel::kunit_case!();
+ //
+ // 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_case!({}, {});",
+ 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_case!();"
+ )
+ .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]", "");
+ 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 3fc74cb4ea19..cd0b720514ff 100644
--- a/rust/macros/lib.rs
+++ b/rust/macros/lib.rs
@@ -6,6 +6,7 @@
mod quote;
mod concat_idents;
mod helpers;
+mod kunit;
mod module;
mod pin_data;
mod pinned_drop;
@@ -246,3 +247,31 @@ pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream {
pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream {
pinned_drop::pinned_drop(args, 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)
+}

--
2.41.0.255.g8b1d071c50-goog