Merge tag 'linux-kselftest-kunit-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull kunit updates from Shuah Khan:

 - add support for running Rust documentation tests as KUnit tests

 - make init, str, sync, types doctests compilable/testable

 - add support for attributes API which include speed, modules
   attributes, ability to filter and report attributes

 - add support for marking tests slow using attributes API

 - add attributes API documentation

 - fix a wild-memory-access bug in kunit_filter_suites() and a possible
   memory leak in kunit_filter_suites()

 - add support for counting number of test suites in a module, list
   action to kunit test modules, and test filtering on module tests

* tag 'linux-kselftest-kunit-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (25 commits)
  kunit: fix struct kunit_attr header
  kunit: replace KUNIT_TRIGGER_STATIC_STUB maro with KUNIT_STATIC_STUB_REDIRECT
  kunit: Allow kunit test modules to use test filtering
  kunit: Make 'list' action available to kunit test modules
  kunit: Report the count of test suites in a module
  kunit: fix uninitialized variables bug in attributes filtering
  kunit: fix possible memory leak in kunit_filter_suites()
  kunit: fix wild-memory-access bug in kunit_filter_suites()
  kunit: Add documentation of KUnit test attributes
  kunit: add tests for filtering attributes
  kunit: time: Mark test as slow using test attributes
  kunit: memcpy: Mark tests as slow using test attributes
  kunit: tool: Add command line interface to filter and report attributes
  kunit: Add ability to filter attributes
  kunit: Add module attribute
  kunit: Add speed attribute
  kunit: Add test attributes API structure
  MAINTAINERS: add Rust KUnit files to the KUnit entry
  rust: support running Rust documentation tests as KUnit ones
  rust: types: make doctests compilable/testable
  ...

1 files changed, 72 insertions, 0 deletions

diff --git a/scripts/rustdoc_test_builder.rs b/scripts/rustdoc_test_builder.rs
new file mode 100644
index 000000000000..e5894652f12c
--- /dev/null
+++ b/scripts/rustdoc_test_builder.rs
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Test builder for `rustdoc`-generated tests.
+//!
+//! This script is a hack to extract the test from `rustdoc`'s output. Ideally, `rustdoc` would
+//! have an option to generate this information instead, e.g. as JSON output.
+//!
+//! The `rustdoc`-generated test names look like `{file}_{line}_{number}`, e.g.
+//! `...path_rust_kernel_sync_arc_rs_42_0`. `number` is the "test number", needed in cases like
+//! a macro that expands into items with doctests is invoked several times within the same line.
+//!
+//! However, since these names are used for bisection in CI, the line number makes it not stable
+//! at all. In the future, we would like `rustdoc` to give us the Rust item path associated with
+//! the test, plus a "test number" (for cases with several examples per item) and generate a name
+//! from that. For the moment, we generate ourselves a new name, `{file}_{number}` instead, in
+//! the `gen` script (done there since we need to be aware of all the tests in a given file).
+
+use std::io::Read;
+
+fn main() {
+    let mut stdin = std::io::stdin().lock();
+    let mut body = String::new();
+    stdin.read_to_string(&mut body).unwrap();
+
+    // Find the generated function name looking for the inner function inside `main()`.
+    //
+    // The line we are looking for looks like one of the following:
+    //
+    // ```
+    // fn main() { #[allow(non_snake_case)] fn _doctest_main_rust_kernel_file_rs_28_0() {
+    // fn main() { #[allow(non_snake_case)] fn _doctest_main_rust_kernel_file_rs_37_0() -> Result<(), impl core::fmt::Debug> {
+    // ```
+    //
+    // It should be unlikely that doctest code matches such lines (when code is formatted properly).
+    let rustdoc_function_name = body
+        .lines()
+        .find_map(|line| {
+            Some(
+                line.split_once("fn main() {")?
+                    .1
+                    .split_once("fn ")?
+                    .1
+                    .split_once("()")?
+                    .0,
+            )
+            .filter(|x| x.chars().all(|c| c.is_alphanumeric() || c == '_'))
+        })
+        .expect("No test function found in `rustdoc`'s output.");
+
+    // Qualify `Result` to avoid the collision with our own `Result` coming from the prelude.
+    let body = body.replace(
+        &format!("{rustdoc_function_name}() -> Result<(), impl core::fmt::Debug> {{"),
+        &format!("{rustdoc_function_name}() -> core::result::Result<(), impl core::fmt::Debug> {{"),
+    );
+
+    // For tests that get generated with `Result`, like above, `rustdoc` generates an `unwrap()` on
+    // the return value to check there were no returned errors. Instead, we use our assert macro
+    // since we want to just fail the test, not panic the kernel.
+    //
+    // We save the result in a variable so that the failed assertion message looks nicer.
+    let body = body.replace(
+        &format!("}} {rustdoc_function_name}().unwrap() }}"),
+        &format!("}} let test_return_value = {rustdoc_function_name}(); assert!(test_return_value.is_ok()); }}"),
+    );
+
+    // Figure out a smaller test name based on the generated function name.
+    let name = rustdoc_function_name.split_once("_rust_kernel_").unwrap().1;
+
+    let path = format!("rust/test/doctests/kernel/{name}");
+
+    std::fs::write(path, body.as_bytes()).unwrap();
+}