function testClientCanSendBatchMessages()
{
$tk = parent::$testKeys;
$currentTime = date("c");
$batch = array();
$attachment = PostmarkAttachment::fromRawData("attachment content", "hello.txt", "text/plain");
for ($i = 0; $i < 5; $i++) {
$payload = array('From' => $tk->WRITE_TEST_SENDER_EMAIL_ADDRESS, 'To' => $tk->WRITE_TEST_EMAIL_RECIPIENT_ADDRESS, 'Subject' => "Hello from the PHP Postmark Client Tests! ({$currentTime})", 'HtmlBody' => '<b>Hi there! (batch test)</b>', 'TextBody' => 'This is a text body for a test email.', 'TrackOpens' => true, 'Headers' => array("X-Test-Header" => "Test Header Content", 'X-Test-Date-Sent' => date('c')), 'Attachments' => array($attachment));
$batch[] = $payload;
}
$client = new PostmarkClient($tk->WRITE_TEST_SERVER_TOKEN, $tk->TEST_TIMEOUT);
$response = $client->sendEmailBatch($batch);
$this->assertNotEmpty($response, 'The client could not send a batch of messages.');
}