public function testWritingFile()
{
$fileName = __DIR__ . '/sitemap_regular.xml';
$sitemap = new Sitemap($fileName);
$sitemap->addItem('http://example.com/mylink1');
$sitemap->addItem('http://example.com/mylink2', time());
$sitemap->addItem('http://example.com/mylink3', time(), Sitemap::HOURLY);
$sitemap->addItem('http://example.com/mylink4', time(), Sitemap::DAILY, 0.3);
$sitemap->write();
$this->assertTrue(file_exists($fileName));
$this->assertIsValidSitemap($fileName);
unlink($fileName);
}