Function check_wait

tests/BS_thread_pool_test.cpp:1427–1445

* @brief Check that wait() works. */

 * @brief Check that wait() works.
 */
void check_wait()
{
    constexpr std::chrono::milliseconds sleep_time(10);
    BS::thread_pool pool;
    const std::size_t num_tasks = pool.get_thread_count() * 10;
    std::vector<std::atomic<bool>> flags(num_tasks);
    for (std::size_t i = 0; i < num_tasks; ++i)
    {
        pool.detach_task(
            [&flags, i, sleep_time]
            {
                std::this_thread::sleep_for(sleep_time);
                flags[i] = true;
            });
    }
    logln("Waiting for tasks...");
    pool.wait();
    check(all_flags_set(flags));
}

/**
 * @brief Check that wait() correctly blocks all external threads that call it.