//! Replay every input the fuzzer has ever found, on stable, in CI.
//!
//! A crash found by `cargo fuzz` becomes a permanent test by copying one file
//! into `fuzz/regressions/`. Nothing else is needed: this walks the directory
//! and runs the same `docengine::oracle::check` the fuzz target runs, so the two
//! cannot drift into checking different things.
//!
//! An empty directory is a passing run and says so. That is not the same as no
//! coverage -- the soak tier is where the searching happens -- but a silently
//! empty replay would look identical to a replay that ran, which is the failure
//! this note exists to prevent.

use std::fs;
use std::path::Path;

#[test]
fn every_fuzz_regression_still_passes() {
    let dir = Path::new(env!("CARGO_MANIFEST_DIR")).join("fuzz/regressions");
    let Ok(entries) = fs::read_dir(&dir) else {
        // Not a failure: a checkout without the directory is a checkout with no
        // regressions yet.
        println!("no regressions directory at {}", dir.display());
        return;
    };

    let mut checked = 0usize;
    for entry in entries {
        let path = entry.expect("reading a regression entry").path();
        if !path.is_file() {
            continue;
        }
        // Lossy on purpose. The corpus is bytes the fuzzer produced, and one
        // that is not valid UTF-8 is still worth replaying through the same
        // conversion the target's `&str` input performs.
        let input =
            String::from_utf8_lossy(&fs::read(&path).expect("reading a regression")).into_owned();
        docengine::oracle::check(&input);
        checked += 1;
    }
    println!(
        "replayed {checked} fuzz regression(s) from {}",
        dir.display()
    );
}