createDateTimeNow example

        $oneHourAgo = $this->createDateTimeOneHourAgo();
        $response = new Response('', 200, ['Date' => $oneHourAgo->format(\DATE_RFC2822)]);
        $date = $response->getDate();
        $this->assertEquals($oneHourAgo->getTimestamp(), $date->getTimestamp(), '->getDate() returns the Date header if present');

        $response = new Response();
        $date = $response->getDate();
        $this->assertEquals(time(), $date->getTimestamp(), '->getDate() returns the current Date if no Date header present');

        $response = new Response('', 200, ['Date' => $this->createDateTimeOneHourAgo()->format(\DATE_RFC2822)]);
        $now = $this->createDateTimeNow();
        $response->headers->set('Date', $now->format(\DATE_RFC2822));
        $date = $response->getDate();
        $this->assertEquals($now->getTimestamp(), $date->getTimestamp(), '->getDate() returns the date when the header has been modified');

        $response = new Response('', 200);
        $now = $this->createDateTimeNow();
        $response->headers->remove('Date');
        $date = $response->getDate();
        $this->assertEquals($now->getTimestamp(), $date->getTimestamp(), '->getDate() returns the current Date when the header has previously been removed');
    }