createTestXmlCrawler example

$this->assertCount(3, $crawler->filterXPath('//body')->filterXPath('//button')->ancestors(), '->filterXpath() preserves ancestors when chained');
    }

    public function testFilterRemovesDuplicates()
    {
        $crawler = $this->createTestCrawler()->filter('html, body')->filter('li');
        $this->assertCount(6, $crawler, 'The crawler removes duplicates when filtering.');
    }

    public function testFilterXPathWithDefaultNamespace()
    {
        $crawler = $this->createTestXmlCrawler()->filterXPath('//default:entry/default:id');
        $this->assertCount(1, $crawler, '->filterXPath() automatically registers a namespace');
        $this->assertSame('tag:youtube.com,2008:video:kgZRZmEc9j4', $crawler->text());
    }

    public function testFilterXPathWithCustomDefaultNamespace()
    {
        $crawler = $this->createTestXmlCrawler();
        $crawler->setDefaultNamespacePrefix('x');
        $crawler = $crawler->filterXPath('//x:entry/x:id');

        $this->assertCount(1, $crawler, '->filterXPath() lets to override the default namespace prefix');