void fn3( boost::fibers::mutex & m, boost::fibers::condition_variable_any & cv) {
    m.lock();
    BOOST_CHECK(test2 == 0);
    test1 = 1;
    cv.notify_one();
    std::chrono::steady_clock::time_point t0 = std::chrono::steady_clock::now();
    std::chrono::steady_clock::time_point t = t0 + ms(250);
    bool r = cv.wait_until(m, t, Pred(test2));
    std::chrono::steady_clock::time_point t1 = std::chrono::steady_clock::now();
    if (runs == 0) {
        BOOST_CHECK(t1 - t0 < ms(250));
        BOOST_CHECK(test2 != 0);
        BOOST_CHECK(r);
    } else {
        BOOST_CHECK(t1 - t0 - ms(250) < ms(250+2));
        BOOST_CHECK(test2 == 0);
        BOOST_CHECK(!r);
    }
    ++runs;
    m.unlock();
}
void fn2( boost::fibers::mutex & m, boost::fibers::condition_variable_any & cv) {
    m.lock();
    BOOST_CHECK(test2 == 0);
    test1 = 1;
    cv.notify_one();
    std::chrono::system_clock::time_point t0 = std::chrono::system_clock::now();
    std::chrono::system_clock::time_point t = t0 + ms(250);
    int count=0;
    while (test2 == 0 && cv.wait_until(m, t) == boost::fibers::cv_status::no_timeout)
        count++;
    std::chrono::system_clock::time_point t1 = std::chrono::system_clock::now();
    if (runs == 0) {
        BOOST_CHECK(t1 - t0 < ms(250));
        BOOST_CHECK(test2 != 0);
    } else {
        BOOST_CHECK(t1 - t0 - ms(250) < ms(count*250+5+1000));
        BOOST_CHECK(test2 == 0);
    }
    ++runs;
    m.unlock();
}