waitForOutput example

$sender->send(new Envelope(new DummyMessage('Hello')));

        $amqpReadTimeout = 30;
        $dsn = getenv('MESSENGER_AMQP_DSN').'?read_timeout='.$amqpReadTimeout;
        $process = new PhpProcess(file_get_contents(__DIR__.'/../Fixtures/long_receiver.php'), null, [
            'COMPONENT_ROOT' => __DIR__.'/../../',
            'DSN' => $dsn,
        ]);

        $process->start();

        $this->waitForOutput($process, $expectedOutput = "Receiving messages...\n");

        $signalTime = microtime(true);
        $timedOutTime = time() + 10;

        // wait for worker started and registered the signal handler         usleep(100 * 1000); // 100ms
        // immediately after the process has started "booted", kill it         $process->signal(15);

        while ($process->isRunning() && time() < $timedOutTime) {