mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 13:55:32 +00:00
261 lines
9.5 KiB
Rust
261 lines
9.5 KiB
Rust
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// SPDX-License-Identifier: GPL-2.0
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//! Generates KUnit tests from saved `rustdoc`-generated tests.
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//!
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//! KUnit passes a context (`struct kunit *`) to each test, which should be forwarded to the other
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//! KUnit functions and macros.
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//!
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//! However, we want to keep this as an implementation detail because:
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//!
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//! - Test code should not care about the implementation.
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//!
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//! - Documentation looks worse if it needs to carry extra details unrelated to the piece
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//! being described.
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//!
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//! - Test code should be able to define functions and call them, without having to carry
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//! the context.
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//!
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//! - Later on, we may want to be able to test non-kernel code (e.g. `core`, `alloc` or
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//! third-party crates) which likely use the standard library `assert*!` macros.
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//!
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//! For this reason, instead of the passed context, `kunit_get_current_test()` is used instead
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//! (i.e. `current->kunit_test`).
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//!
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//! Note that this means other threads/tasks potentially spawned by a given test, if failing, will
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//! report the failure in the kernel log but will not fail the actual test. Saving the pointer in
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//! e.g. a `static` per test does not fully solve the issue either, because currently KUnit does
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//! not support assertions (only expectations) from other tasks. Thus leave that feature for
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//! the future, which simplifies the code here too. We could also simply not allow `assert`s in
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//! other tasks, but that seems overly constraining, and we do want to support them, eventually.
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use std::{
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fs,
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fs::File,
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io::{BufWriter, Read, Write},
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path::{Path, PathBuf},
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};
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/// Find the real path to the original file based on the `file` portion of the test name.
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///
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/// `rustdoc` generated `file`s look like `sync_locked_by_rs`. Underscores (except the last one)
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/// may represent an actual underscore in a directory/file, or a path separator. Thus the actual
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/// file might be `sync_locked_by.rs`, `sync/locked_by.rs`, `sync_locked/by.rs` or
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/// `sync/locked/by.rs`. This function walks the file system to determine which is the real one.
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///
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/// This does require that ambiguities do not exist, but that seems fair, especially since this is
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/// all supposed to be temporary until `rustdoc` gives us proper metadata to build this. If such
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/// ambiguities are detected, they are diagnosed and the script panics.
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fn find_real_path<'a>(srctree: &Path, valid_paths: &'a mut Vec<PathBuf>, file: &str) -> &'a str {
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valid_paths.clear();
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let potential_components: Vec<&str> = file.strip_suffix("_rs").unwrap().split('_').collect();
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find_candidates(srctree, valid_paths, Path::new(""), &potential_components);
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fn find_candidates(
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srctree: &Path,
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valid_paths: &mut Vec<PathBuf>,
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prefix: &Path,
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potential_components: &[&str],
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) {
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// The base case: check whether all the potential components left, joined by underscores,
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// is a file.
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let joined_potential_components = potential_components.join("_") + ".rs";
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if srctree
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.join("rust/kernel")
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.join(prefix)
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.join(&joined_potential_components)
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.is_file()
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{
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// Avoid `srctree` here in order to keep paths relative to it in the KTAP output.
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valid_paths.push(
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Path::new("rust/kernel")
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.join(prefix)
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.join(joined_potential_components),
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);
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}
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// In addition, check whether each component prefix, joined by underscores, is a directory.
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// If not, there is no need to check for combinations with that prefix.
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for i in 1..potential_components.len() {
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let (components_prefix, components_rest) = potential_components.split_at(i);
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let prefix = prefix.join(components_prefix.join("_"));
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if srctree.join("rust/kernel").join(&prefix).is_dir() {
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find_candidates(srctree, valid_paths, &prefix, components_rest);
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}
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}
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}
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assert!(
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valid_paths.len() > 0,
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"No path candidates found. This is likely a bug in the build system, or some files went \
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away while compiling."
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);
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if valid_paths.len() > 1 {
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eprintln!("Several path candidates found:");
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for path in valid_paths {
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eprintln!(" {path:?}");
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}
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panic!(
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"Several path candidates found, please resolve the ambiguity by renaming a file or \
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folder."
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);
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}
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valid_paths[0].to_str().unwrap()
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}
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fn main() {
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let srctree = std::env::var("srctree").unwrap();
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let srctree = Path::new(&srctree);
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let mut paths = fs::read_dir("rust/test/doctests/kernel")
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.unwrap()
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.map(|entry| entry.unwrap().path())
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.collect::<Vec<_>>();
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// Sort paths.
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paths.sort();
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let mut rust_tests = String::new();
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let mut c_test_declarations = String::new();
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let mut c_test_cases = String::new();
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let mut body = String::new();
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let mut last_file = String::new();
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let mut number = 0;
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let mut valid_paths: Vec<PathBuf> = Vec::new();
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let mut real_path: &str = "";
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for path in paths {
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// The `name` follows the `{file}_{line}_{number}` pattern (see description in
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// `scripts/rustdoc_test_builder.rs`). Discard the `number`.
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let name = path.file_name().unwrap().to_str().unwrap().to_string();
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// Extract the `file` and the `line`, discarding the `number`.
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let (file, line) = name.rsplit_once('_').unwrap().0.rsplit_once('_').unwrap();
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// Generate an ID sequence ("test number") for each one in the file.
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if file == last_file {
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number += 1;
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} else {
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number = 0;
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last_file = file.to_string();
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// Figure out the real path, only once per file.
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real_path = find_real_path(srctree, &mut valid_paths, file);
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}
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// Generate a KUnit name (i.e. test name and C symbol) for this test.
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//
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// We avoid the line number, like `rustdoc` does, to make things slightly more stable for
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// bisection purposes. However, to aid developers in mapping back what test failed, we will
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// print a diagnostics line in the KTAP report.
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let kunit_name = format!("rust_doctest_kernel_{file}_{number}");
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// Read the test's text contents to dump it below.
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body.clear();
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File::open(path).unwrap().read_to_string(&mut body).unwrap();
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// Calculate how many lines before `main` function (including the `main` function line).
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let body_offset = body
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.lines()
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.take_while(|line| !line.contains("fn main() {"))
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.count()
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+ 1;
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use std::fmt::Write;
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write!(
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rust_tests,
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r#"/// Generated `{name}` KUnit test case from a Rust documentation test.
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#[no_mangle]
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pub extern "C" fn {kunit_name}(__kunit_test: *mut kernel::bindings::kunit) {{
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/// Overrides the usual [`assert!`] macro with one that calls KUnit instead.
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#[allow(unused)]
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macro_rules! assert {{
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($cond:expr $(,)?) => {{{{
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kernel::kunit_assert!("{kunit_name}", "{real_path}", __DOCTEST_ANCHOR - {line}, $cond);
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}}}}
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}}
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/// Overrides the usual [`assert_eq!`] macro with one that calls KUnit instead.
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#[allow(unused)]
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macro_rules! assert_eq {{
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($left:expr, $right:expr $(,)?) => {{{{
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kernel::kunit_assert_eq!("{kunit_name}", "{real_path}", __DOCTEST_ANCHOR - {line}, $left, $right);
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}}}}
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}}
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// Many tests need the prelude, so provide it by default.
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#[allow(unused)]
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use kernel::prelude::*;
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// Unconditionally print the location of the original doctest (i.e. rather than the location in
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// the generated file) so that developers can easily map the test back to the source code.
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//
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// This information is also printed when assertions fail, but this helps in the successful cases
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// when the user is running KUnit manually, or when passing `--raw_output` to `kunit.py`.
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//
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// This follows the syntax for declaring test metadata in the proposed KTAP v2 spec, which may
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// be used for the proposed KUnit test attributes API. Thus hopefully this will make migration
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// easier later on.
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kernel::kunit::info(format_args!(" # {kunit_name}.location: {real_path}:{line}\n"));
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/// The anchor where the test code body starts.
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#[allow(unused)]
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static __DOCTEST_ANCHOR: i32 = core::line!() as i32 + {body_offset} + 1;
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{{
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{body}
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main();
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}}
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}}
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"#
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)
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.unwrap();
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write!(c_test_declarations, "void {kunit_name}(struct kunit *);\n").unwrap();
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write!(c_test_cases, " KUNIT_CASE({kunit_name}),\n").unwrap();
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}
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let rust_tests = rust_tests.trim();
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let c_test_declarations = c_test_declarations.trim();
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let c_test_cases = c_test_cases.trim();
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write!(
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BufWriter::new(File::create("rust/doctests_kernel_generated.rs").unwrap()),
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r#"//! `kernel` crate documentation tests.
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const __LOG_PREFIX: &[u8] = b"rust_doctests_kernel\0";
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{rust_tests}
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"#
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)
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.unwrap();
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write!(
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BufWriter::new(File::create("rust/doctests_kernel_generated_kunit.c").unwrap()),
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r#"/*
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* `kernel` crate documentation tests.
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*/
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#include <kunit/test.h>
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{c_test_declarations}
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static struct kunit_case test_cases[] = {{
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{c_test_cases}
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{{ }}
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}};
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static struct kunit_suite test_suite = {{
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.name = "rust_doctests_kernel",
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.test_cases = test_cases,
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}};
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kunit_test_suite(test_suite);
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MODULE_LICENSE("GPL");
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"#
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)
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.unwrap();
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}
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