name : rustdoc_test_gen.rs // SPDX-License-Identifier: GPL-2.0 //! Generates KUnit tests from saved `rustdoc`-generated tests. //! //! KUnit passes a context (`struct kunit *`) to each test, which should be forwarded to the other //! KUnit functions and macros. //! //! However, we want to keep this as an implementation detail because: //! //! - Test code should not care about the implementation. //! //! - Documentation looks worse if it needs to carry extra details unrelated to the piece //! being described. //! //! - Test code should be able to define functions and call them, without having to carry //! the context. //! //! - Later on, we may want to be able to test non-kernel code (e.g. `core`, `alloc` or //! third-party crates) which likely use the standard library `assert*!` macros. //! //! For this reason, instead of the passed context, `kunit_get_current_test()` is used instead //! (i.e. `current->kunit_test`). //! //! Note that this means other threads/tasks potentially spawned by a given test, if failing, will //! report the failure in the kernel log but will not fail the actual test. Saving the pointer in //! e.g. a `static` per test does not fully solve the issue either, because currently KUnit does //! not support assertions (only expectations) from other tasks. Thus leave that feature for //! the future, which simplifies the code here too. We could also simply not allow `assert`s in //! other tasks, but that seems overly constraining, and we do want to support them, eventually. use std::{ fs, fs::File, io::{BufWriter, Read, Write}, path::{Path, PathBuf}, }; /// Find the real path to the original file based on the `file` portion of the test name. /// /// `rustdoc` generated `file`s look like `sync_locked_by_rs`. Underscores (except the last one) /// may represent an actual underscore in a directory/file, or a path separator. Thus the actual /// file might be `sync_locked_by.rs`, `sync/locked_by.rs`, `sync_locked/by.rs` or /// `sync/locked/by.rs`. This function walks the file system to determine which is the real one. /// /// This does require that ambiguities do not exist, but that seems fair, especially since this is /// all supposed to be temporary until `rustdoc` gives us proper metadata to build this. If such /// ambiguities are detected, they are diagnosed and the script panics. fn find_real_path<'a>(srctree: &Path, valid_paths: &'a mut Vec<PathBuf>, file: &str) -> &'a str { valid_paths.clear(); let potential_components: Vec<&str> = file.strip_suffix("_rs").unwrap().split('_').collect(); find_candidates(srctree, valid_paths, Path::new(""), &potential_components); fn find_candidates( srctree: &Path, valid_paths: &mut Vec<PathBuf>, prefix: &Path, potential_components: &[&str], ) { // The base case: check whether all the potential components left, joined by underscores, // is a file. let joined_potential_components = potential_components.join("_") + ".rs"; if srctree .join("rust/kernel") .join(prefix) .join(&joined_potential_components) .is_file() { // Avoid `srctree` here in order to keep paths relative to it in the KTAP output. valid_paths.push( Path::new("rust/kernel") .join(prefix) .join(joined_potential_components), ); } // In addition, check whether each component prefix, joined by underscores, is a directory. // If not, there is no need to check for combinations with that prefix. for i in 1..potential_components.len() { let (components_prefix, components_rest) = potential_components.split_at(i); let prefix = prefix.join(components_prefix.join("_")); if srctree.join("rust/kernel").join(&prefix).is_dir() { find_candidates(srctree, valid_paths, &prefix, components_rest); } } } assert!( valid_paths.len() > 0, "No path candidates found. This is likely a bug in the build system, or some files went \ away while compiling." ); if valid_paths.len() > 1 { eprintln!("Several path candidates found:"); for path in valid_paths { eprintln!(" {path:?}"); } panic!( "Several path candidates found, please resolve the ambiguity by renaming a file or \ folder." ); } valid_paths[0].to_str().unwrap() } fn main() { let srctree = std::env::var("srctree").unwrap(); let srctree = Path::new(&srctree); let mut paths = fs::read_dir("rust/test/doctests/kernel") .unwrap() .map(|entry| entry.unwrap().path()) .collect::<Vec<_>>(); // Sort paths. paths.sort(); let mut rust_tests = String::new(); let mut c_test_declarations = String::new(); let mut c_test_cases = String::new(); let mut body = String::new(); let mut last_file = String::new(); let mut number = 0; let mut valid_paths: Vec<PathBuf> = Vec::new(); let mut real_path: &str = ""; for path in paths { // The `name` follows the `{file}_{line}_{number}` pattern (see description in // `scripts/rustdoc_test_builder.rs`). Discard the `number`. let name = path.file_name().unwrap().to_str().unwrap().to_string(); // Extract the `file` and the `line`, discarding the `number`. let (file, line) = name.rsplit_once('_').unwrap().0.rsplit_once('_').unwrap(); // Generate an ID sequence ("test number") for each one in the file. if file == last_file { number += 1; } else { number = 0; last_file = file.to_string(); // Figure out the real path, only once per file. real_path = find_real_path(srctree, &mut valid_paths, file); } // Generate a KUnit name (i.e. test name and C symbol) for this test. // // We avoid the line number, like `rustdoc` does, to make things slightly more stable for // bisection purposes. However, to aid developers in mapping back what test failed, we will // print a diagnostics line in the KTAP report. let kunit_name = format!("rust_doctest_kernel_{file}_{number}"); // Read the test's text contents to dump it below. body.clear(); File::open(path).unwrap().read_to_string(&mut body).unwrap(); // Calculate how many lines before `main` function (including the `main` function line). let body_offset = body .lines() .take_while(|line| !line.contains("fn main() {")) .count() + 1; use std::fmt::Write; write!( rust_tests, r#"/// Generated `{name}` KUnit test case from a Rust documentation test. #[no_mangle] pub extern "C" fn {kunit_name}(__kunit_test: *mut kernel::bindings::kunit) {{ /// Overrides the usual [`assert!`] macro with one that calls KUnit instead. #[allow(unused)] macro_rules! assert {{ ($cond:expr $(,)?) => {{{{ kernel::kunit_assert!("{kunit_name}", "{real_path}", __DOCTEST_ANCHOR - {line}, $cond); }}}} }} /// Overrides the usual [`assert_eq!`] macro with one that calls KUnit instead. #[allow(unused)] macro_rules! assert_eq {{ ($left:expr, $right:expr $(,)?) => {{{{ kernel::kunit_assert_eq!("{kunit_name}", "{real_path}", __DOCTEST_ANCHOR - {line}, $left, $right); }}}} }} // Many tests need the prelude, so provide it by default. #[allow(unused)] use kernel::prelude::*; // Unconditionally print the location of the original doctest (i.e. rather than the location in // the generated file) so that developers can easily map the test back to the source code. // // This information is also printed when assertions fail, but this helps in the successful cases // when the user is running KUnit manually, or when passing `--raw_output` to `kunit.py`. // // This follows the syntax for declaring test metadata in the proposed KTAP v2 spec, which may // be used for the proposed KUnit test attributes API. Thus hopefully this will make migration // easier later on. kernel::kunit::info(format_args!(" # {kunit_name}.location: {real_path}:{line}\n")); /// The anchor where the test code body starts. #[allow(unused)] static __DOCTEST_ANCHOR: i32 = core::line!() as i32 + {body_offset} + 1; {{ {body} main(); }} }} "# ) .unwrap(); write!(c_test_declarations, "void {kunit_name}(struct kunit *);\n").unwrap(); write!(c_test_cases, " KUNIT_CASE({kunit_name}),\n").unwrap(); } let rust_tests = rust_tests.trim(); let c_test_declarations = c_test_declarations.trim(); let c_test_cases = c_test_cases.trim(); write!( BufWriter::new(File::create("rust/doctests_kernel_generated.rs").unwrap()), r#"//! `kernel` crate documentation tests. const __LOG_PREFIX: &[u8] = b"rust_doctests_kernel\0"; {rust_tests} "# ) .unwrap(); write!( BufWriter::new(File::create("rust/doctests_kernel_generated_kunit.c").unwrap()), r#"/* * `kernel` crate documentation tests. */ #include <kunit/test.h> {c_test_declarations} static struct kunit_case test_cases[] = {{ {c_test_cases} {{ }} }}; static struct kunit_suite test_suite = {{ .name = "rust_doctests_kernel", .test_cases = test_cases, }}; kunit_test_suite(test_suite); MODULE_LICENSE("GPL"); "# ) .unwrap(); }