name : rustdoc_test_builder.rs // 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(); }