launcher/src/ui_test_lock.rs

//! Process-global lock serializing the two Playwright UI test suites (the
//! web dashboard's `ui_playwright_checks` and the report viewer's
//! `report_playwright_checks`). Both launch a chromium instance via deno;
//! running them concurrently on the same machine flakes (browser
//! contention), so `make check` serializes them through this guard.
//!
//! The guard is acquired inside `spawn_blocking` closures (blocking
//! context, no await held) — see the callers in `web/tests.rs` and
//! `report/ui_tests.rs`.

#![cfg(test)]

use std::sync::{Mutex, MutexGuard, PoisonError};

pub static PLAYWRIGHT_LOCK: Mutex<()> = Mutex::new(());

/// Serializes the tests that change the process cwd (`set_current_dir`) with
/// the tests that read cwd-relative state (`./config.toml`, the recipe search
/// order). Cargo runs test functions in parallel threads of one process, so a
/// chdir in one test would otherwise re-point the others mid-flight. A tokio
/// mutex (not std) because the holders await their HTTP round-trips.
fn cwd_mutex() -> &'static tokio::sync::Mutex<()> {
    static LOCK: std::sync::OnceLock<tokio::sync::Mutex<()>> = std::sync::OnceLock::new();
    LOCK.get_or_init(|| tokio::sync::Mutex::new(()))
}

/// Acquire the cwd lock; held until the guard is dropped.
pub async fn cwd_guard() -> tokio::sync::MutexGuard<'static, ()> {
    cwd_mutex().lock().await
}

/// Acquire the Playwright session lock; held until the guard is dropped.
/// Tolerates a poisoned lock (a panicked holder) — the browser is the
/// shared resource, not the lock's payload.
pub fn playwright_session() -> MutexGuard<'static, ()> {
    PLAYWRIGHT_LOCK
        .lock()
        .unwrap_or_else(PoisonError::into_inner)
}