clearCommands example

$stream = new DummyStream();
        $envelope = new Envelope(new Address('sender@example.org'), [new Address('recipient@example.org')]);

        $transport = new SmtpTransport($stream);
        $transport->setPingThreshold(1);

        $transport->send(new RawMessage('Message 1'), $envelope);
        $transport->send(new RawMessage('Message 2'), $envelope);

        $this->assertNotContains("NOOP\r\n", $stream->getCommands());

        $stream->clearCommands();
        usleep(1500000);

        $transport->send(new RawMessage('Message 3'), $envelope);
        $this->assertContains("NOOP\r\n", $stream->getCommands());
    }

    public function testSendInvalidMessage()
    {
        $stream = new DummyStream();

        $transport = new SmtpTransport($stream);