LinkGeneratorTest.php

<?php

namespace Drupal\Tests\Core\Utility;

use Drupal\Component\Render\MarkupInterface;
use Drupal\Core\GeneratedButton;
use Drupal\Core\GeneratedNoLink;
use Drupal\Core\GeneratedUrl;
use Drupal\Core\Language\Language;
use Drupal\Core\Link;
use Drupal\Core\Render\Markup;
use Drupal\Core\Url;
use Drupal\Core\Utility\LinkGenerator;
use Drupal\Tests\UnitTestCase;
use Drupal\Core\DependencyInjection\ContainerBuilder;

/**
 * @coversDefaultClass \Drupal\Core\Utility\LinkGenerator
 * @group Utility
 */
class LinkGeneratorTest extends UnitTestCase {
    
    /**
     * The tested link generator.
     *
     * @var \Drupal\Core\Utility\LinkGenerator
     */
    protected $linkGenerator;
    
    /**
     * The mocked URL generator.
     *
     * @var \PHPUnit\Framework\MockObject\MockObject
     */
    protected $urlGenerator;
    
    /**
     * The mocked module handler.
     *
     * @var \PHPUnit\Framework\MockObject\MockObject
     */
    protected $moduleHandler;
    
    /**
     * The mocked renderer service.
     *
     * @var \PHPUnit\Framework\MockObject\MockObject|\Drupal\Core\Render\RendererInterface
     */
    protected $renderer;
    
    /**
     * The mocked URL Assembler service.
     *
     * @var \PHPUnit\Framework\MockObject\MockObject|\Drupal\Core\Utility\UnroutedUrlAssemblerInterface
     */
    protected $urlAssembler;
    
    /**
     * Contains the LinkGenerator default options.
     */
    protected $defaultOptions = [
        'query' => [],
        'language' => NULL,
        'set_active_class' => FALSE,
        'absolute' => FALSE,
    ];
    
    /**
     * {@inheritdoc}
     */
    protected function setUp() : void {
        parent::setUp();
        $this->urlGenerator = $this->getMockBuilder('\\Drupal\\Core\\Routing\\UrlGenerator')
            ->disableOriginalConstructor()
            ->getMock();
        $this->moduleHandler = $this->createMock('Drupal\\Core\\Extension\\ModuleHandlerInterface');
        $this->renderer = $this->createMock('\\Drupal\\Core\\Render\\RendererInterface');
        $this->linkGenerator = new LinkGenerator($this->urlGenerator, $this->moduleHandler, $this->renderer);
        $this->urlAssembler = $this->createMock('\\Drupal\\Core\\Utility\\UnroutedUrlAssemblerInterface');
    }
    
    /**
     * Provides test data for testing the link method.
     *
     * @see \Drupal\Tests\Core\Utility\LinkGeneratorTest::testGenerateHrefs()
     *
     * @return array
     *   Returns some test data.
     */
    public function providerTestGenerateHrefs() {
        return [
            // Test that the URL returned by the URL generator is used.
[
                'test_route_1',
                [],
                FALSE,
                '/test-route-1',
            ],
            // Test that $parameters is passed to the URL generator.
[
                'test_route_2',
                [
                    'value' => 'example',
                ],
                FALSE,
                '/test-route-2/example',
            ],
            // Test that the 'absolute' option is passed to the URL generator.
[
                'test_route_3',
                [],
                TRUE,
                'http://example.com/test-route-3',
            ],
        ];
    }
    
    /**
     * Tests the link method with certain hrefs.
     *
     * @see \Drupal\Core\Utility\LinkGenerator::generate()
     * @see \Drupal\Tests\Core\Utility\LinkGeneratorTest::providerTestGenerate()
     *
     * @dataProvider providerTestGenerateHrefs
     */
    public function testGenerateHrefs($route_name, array $parameters, $absolute, $expected_url) {
        $this->urlGenerator
            ->expects($this->once())
            ->method('generateFromRoute')
            ->with($route_name, $parameters, [
            'absolute' => $absolute,
        ] + $this->defaultOptions)
            ->willReturn((new GeneratedUrl())->setGeneratedUrl($expected_url));
        $this->moduleHandler
            ->expects($this->once())
            ->method('alter');
        $url = new Url($route_name, $parameters, [
            'absolute' => $absolute,
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertLink([
            'attributes' => [
                'href' => $expected_url,
            ],
        ], $result);
    }
    
    /**
     * Tests the generate() method with a route.
     *
     * @covers ::generate
     */
    public function testGenerate() {
        $this->urlGenerator
            ->expects($this->once())
            ->method('generateFromRoute')
            ->with('test_route_1', [], [
            'fragment' => 'the-fragment',
        ] + $this->defaultOptions)
            ->willReturn((new GeneratedUrl())->setGeneratedUrl('/test-route-1#the-fragment'));
        $this->moduleHandler
            ->expects($this->once())
            ->method('alter')
            ->with('link', $this->isType('array'));
        $url = new Url('test_route_1', [], [
            'fragment' => 'the-fragment',
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertLink([
            'attributes' => [
                'href' => '/test-route-1#the-fragment',
            ],
            'content' => 'Test',
        ], $result);
    }
    
    /**
     * Tests the generate() method with the <nolink> route.
     *
     * The set_active_class option is set to TRUE to ensure we do not get the
     * active class and the data-drupal-link-system-path attribute.
     *
     * @covers ::generate
     */
    public function testGenerateNoLink() {
        $this->urlGenerator
            ->expects($this->never())
            ->method('generateFromRoute');
        $this->moduleHandler
            ->expects($this->exactly(2))
            ->method('alter')
            ->with('link', $this->isType('array'));
        $url = Url::fromRoute('<nolink>');
        $url->setUrlGenerator($this->urlGenerator);
        $url->setOption('set_active_class', TRUE);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertInstanceOf(GeneratedNoLink::class, $result);
        $this->assertSame('<span>Test</span>', (string) $result);
        // Validate removal of hreflang attributes.
        $url = Url::fromRoute('<nolink>', [], [
            'language' => new Language([
                'id' => 'de',
            ]),
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test With Language', $url);
        $this->assertSame('<span>Test With Language</span>', (string) $result);
    }
    
    /**
     * Tests the generate() method with the <none> route.
     *
     * The set_active_class option is set to TRUE to ensure we do not get the
     * active class and the data-drupal-link-system-path attribute.
     *
     * @covers ::generate
     */
    public function testGenerateNone() {
        $this->urlGenerator
            ->expects($this->once())
            ->method('generateFromRoute')
            ->with('<none>', [], [
            'set_active_class' => TRUE,
        ] + $this->defaultOptions)
            ->willReturn((new GeneratedUrl())->setGeneratedUrl(''));
        $this->moduleHandler
            ->expects($this->once())
            ->method('alter')
            ->with('link', $this->isType('array'));
        $url = Url::fromRoute('<none>');
        $url->setUrlGenerator($this->urlGenerator);
        $url->setOption('set_active_class', TRUE);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertSame('<a href="">Test</a>', (string) $result);
    }
    
    /**
     * Tests the generate() method with the <button> route.
     *
     * @covers ::generate
     */
    public function testGenerateButton() {
        $this->urlGenerator
            ->expects($this->never())
            ->method('generateFromRoute');
        $this->moduleHandler
            ->expects($this->exactly(2))
            ->method('alter')
            ->with('link', $this->isType('array'));
        $url = Url::fromRoute('<button>');
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertInstanceOf(GeneratedButton::class, $result);
        $this->assertSame('<button type="button">Test</button>', (string) $result);
        // Validate removal of hreflang attributes.
        $url = new Url('<button>', [], [
            'language' => new Language([
                'id' => 'de',
            ]),
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test With Language', $url);
        $this->assertSame('<button type="button">Test With Language</button>', (string) $result);
    }
    
    /**
     * Tests the generate() method with an external URL.
     *
     * The set_active_class option is set to TRUE to ensure this does not cause
     * an error together with an external URL.
     *
     * @covers ::generate
     */
    public function testGenerateExternal() {
        $this->urlAssembler
            ->expects($this->once())
            ->method('assemble')
            ->with('https://www.drupal.org', [
            'set_active_class' => TRUE,
            'external' => TRUE,
        ] + $this->defaultOptions)
            ->will($this->returnArgument(0));
        $this->moduleHandler
            ->expects($this->once())
            ->method('alter')
            ->with('link', $this->isType('array'));
        $this->urlAssembler
            ->expects($this->once())
            ->method('assemble')
            ->with('https://www.drupal.org', [
            'set_active_class' => TRUE,
            'external' => TRUE,
        ] + $this->defaultOptions)
            ->willReturnArgument(0);
        $url = Url::fromUri('https://www.drupal.org');
        $url->setUrlGenerator($this->urlGenerator);
        $url->setUnroutedUrlAssembler($this->urlAssembler);
        $url->setOption('set_active_class', TRUE);
        $result = $this->linkGenerator
            ->generate('Drupal', $url);
        $this->assertLink([
            'attributes' => [
                'href' => 'https://www.drupal.org',
            ],
            'content' => 'Drupal',
        ], $result);
    }
    
    /**
     * Tests the generate() method with a URL containing double quotes.
     *
     * @covers ::generate
     */
    public function testGenerateUrlWithQuotes() {
        $this->urlAssembler
            ->expects($this->once())
            ->method('assemble')
            ->with('base:example', [
            'query' => [
                'foo' => '"bar"',
                'zoo' => 'baz',
            ],
        ] + $this->defaultOptions)
            ->willReturn((new GeneratedUrl())->setGeneratedUrl('/example?foo=%22bar%22&zoo=baz'));
        $path_validator = $this->createMock('Drupal\\Core\\Path\\PathValidatorInterface');
        $container_builder = new ContainerBuilder();
        $container_builder->set('path.validator', $path_validator);
        \Drupal::setContainer($container_builder);
        $path = '/example?foo="bar"&zoo=baz';
        $url = Url::fromUserInput($path);
        $url->setUrlGenerator($this->urlGenerator);
        $url->setUnroutedUrlAssembler($this->urlAssembler);
        $result = $this->linkGenerator
            ->generate('Drupal', $url);
        $this->assertLink([
            'attributes' => [
                'href' => '/example?foo=%22bar%22&zoo=baz',
            ],
            'content' => 'Drupal',
        ], $result, 1);
    }
    
    /**
     * Tests the link method with additional attributes.
     *
     * @see \Drupal\Core\Utility\LinkGenerator::generate()
     */
    public function testGenerateAttributes() {
        $this->urlGenerator
            ->expects($this->once())
            ->method('generateFromRoute')
            ->with('test_route_1', [], $this->defaultOptions)
            ->willReturn((new GeneratedUrl())->setGeneratedUrl('/test-route-1'));
        // Test that HTML attributes are added to the anchor.
        $url = new Url('test_route_1', [], [
            'attributes' => [
                'title' => 'Tooltip',
            ],
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertLink([
            'attributes' => [
                'href' => '/test-route-1',
                'title' => 'Tooltip',
            ],
        ], $result);
    }
    
    /**
     * Tests the link method with passed query options.
     *
     * @see \Drupal\Core\Utility\LinkGenerator::generate()
     */
    public function testGenerateQuery() {
        $this->urlGenerator
            ->expects($this->once())
            ->method('generateFromRoute')
            ->with('test_route_1', [], [
            'query' => [
                'test' => 'value',
            ],
        ] + $this->defaultOptions)
            ->willReturn((new GeneratedUrl())->setGeneratedUrl('/test-route-1?test=value'));
        $url = new Url('test_route_1', [], [
            'query' => [
                'test' => 'value',
            ],
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertLink([
            'attributes' => [
                'href' => '/test-route-1?test=value',
            ],
        ], $result);
    }
    
    /**
     * Tests the link method with passed query options via parameters.
     *
     * @see \Drupal\Core\Utility\LinkGenerator::generate()
     */
    public function testGenerateParametersAsQuery() {
        $this->urlGenerator
            ->expects($this->once())
            ->method('generateFromRoute')
            ->with('test_route_1', [
            'test' => 'value',
        ], $this->defaultOptions)
            ->willReturn((new GeneratedUrl())->setGeneratedUrl('/test-route-1?test=value'));
        $url = new Url('test_route_1', [
            'test' => 'value',
        ], []);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertLink([
            'attributes' => [
                'href' => '/test-route-1?test=value',
            ],
        ], $result);
    }
    
    /**
     * Tests the link method with arbitrary passed options.
     *
     * @see \Drupal\Core\Utility\LinkGenerator::generate()
     */
    public function testGenerateOptions() {
        $this->urlGenerator
            ->expects($this->once())
            ->method('generateFromRoute')
            ->with('test_route_1', [], [
            'key' => 'value',
        ] + $this->defaultOptions)
            ->willReturn((new GeneratedUrl())->setGeneratedUrl('/test-route-1?test=value'));
        $url = new Url('test_route_1', [], [
            'key' => 'value',
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertLink([
            'attributes' => [
                'href' => '/test-route-1?test=value',
            ],
        ], $result);
    }
    
    /**
     * Tests the link method with a script tab.
     *
     * @see \Drupal\Core\Utility\LinkGenerator::generate()
     */
    public function testGenerateXss() {
        $this->urlGenerator
            ->expects($this->once())
            ->method('generateFromRoute')
            ->with('test_route_4', [], $this->defaultOptions)
            ->willReturn((new GeneratedUrl())->setGeneratedUrl('/test-route-4'));
        // Test that HTML link text is escaped by default.
        $url = new Url('test_route_4');
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate("<script>alert('XSS!')</script>", $url);
        $this->assertNoXPathResults('//a[@href="/test-route-4"]/script', $result);
    }
    
    /**
     * Tests the link method with html.
     *
     * @see \Drupal\Core\Utility\LinkGenerator::generate()
     */
    public function testGenerateWithHtml() {
        $this->urlGenerator
            ->expects($this->exactly(2))
            ->method('generateFromRoute')
            ->with('test_route_5', [], $this->defaultOptions)
            ->willReturn((new GeneratedUrl())->setGeneratedUrl('/test-route-5'));
        // Test that HTML tags are stripped from the 'title' attribute.
        $url = new Url('test_route_5', [], [
            'attributes' => [
                'title' => '<em>HTML Tooltip</em>',
            ],
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertLink([
            'attributes' => [
                'href' => '/test-route-5',
                'title' => 'HTML Tooltip',
            ],
        ], $result);
        // Test that safe HTML is output inside the anchor tag unescaped. The
        // Markup::create() call is an intentional unit test for the interaction
        // between MarkupInterface and the LinkGenerator.
        $url = new Url('test_route_5', []);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate(Markup::create('<em>HTML output</em>'), $url);
        $this->assertLink([
            'attributes' => [
                'href' => '/test-route-5',
            ],
            'child' => [
                'tag' => 'em',
            ],
        ], $result);
        $this->assertStringContainsString('<em>HTML output</em>', $result);
    }
    
    /**
     * Tests the active class on the link method.
     *
     * @see \Drupal\Core\Utility\LinkGenerator::generate()
     */
    public function testGenerateActive() {
        $this->urlGenerator
            ->expects($this->exactly(5))
            ->method('generateFromRoute')
            ->willReturnCallback(function ($name, $parameters = [], $options = [], $collect_bubbleable_metadata = FALSE) {
            switch ($name) {
                case 'test_route_1':
                    return (new GeneratedUrl())->setGeneratedUrl('/test-route-1');
                case 'test_route_3':
                    return (new GeneratedUrl())->setGeneratedUrl('/test-route-3');
                case 'test_route_4':
                    if ($parameters['object'] == '1') {
                        return (new GeneratedUrl())->setGeneratedUrl('/test-route-4/1');
                    }
            }
        });
        $this->urlGenerator
            ->expects($this->exactly(4))
            ->method('getPathFromRoute')
            ->willReturnMap([
            [
                'test_route_1',
                [],
                'test-route-1',
            ],
            [
                'test_route_3',
                [],
                'test-route-3',
            ],
            [
                'test_route_4',
                [
                    'object' => '1',
                ],
                'test-route-4/1',
            ],
        ]);
        $this->moduleHandler
            ->expects($this->exactly(5))
            ->method('alter');
        // Render a link.
        $url = new Url('test_route_1', [], [
            'set_active_class' => TRUE,
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertLink([
            'attributes' => [
                'data-drupal-link-system-path' => 'test-route-1',
            ],
        ], $result);
        // Render a link with the set_active_class option disabled.
        $url = new Url('test_route_1', [], [
            'set_active_class' => FALSE,
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertNoXPathResults('//a[@data-drupal-link-system-path="test-route-1"]', $result);
        // Render a link with an associated language.
        $url = new Url('test_route_1', [], [
            'language' => new Language([
                'id' => 'de',
            ]),
            'set_active_class' => TRUE,
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertLink([
            'attributes' => [
                'data-drupal-link-system-path' => 'test-route-1',
                'hreflang' => 'de',
            ],
        ], $result);
        // Render a link with a query parameter.
        $url = new Url('test_route_3', [], [
            'query' => [
                'value' => 'example_1',
            ],
            'set_active_class' => TRUE,
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertLink([
            'attributes' => [
                'data-drupal-link-system-path' => 'test-route-3',
                'data-drupal-link-query' => '{"value":"example_1"}',
            ],
        ], $result);
        // Render a link with route parameters and a query parameter.
        $url = new Url('test_route_4', [
            'object' => '1',
        ], [
            'query' => [
                'value' => 'example_1',
            ],
            'set_active_class' => TRUE,
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $result = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertLink([
            'attributes' => [
                'data-drupal-link-system-path' => 'test-route-4/1',
                'data-drupal-link-query' => '{"value":"example_1"}',
            ],
        ], $result);
    }
    
    /**
     * Tests the LinkGenerator's support for collecting bubbleable metadata.
     *
     * @see \Drupal\Core\Utility\LinkGenerator::generate()
     * @see \Drupal\Core\Utility\LinkGenerator::generateFromLink()
     */
    public function testGenerateBubbleableMetadata() {
        $options = [
            'query' => [],
            'language' => NULL,
            'set_active_class' => FALSE,
            'absolute' => FALSE,
        ];
        $this->urlGenerator
            ->expects($this->any())
            ->method('generateFromRoute')
            ->willReturnMap([
            [
                'test_route_1',
                [],
                $options,
                TRUE,
                (new GeneratedUrl())->setGeneratedUrl('/test-route-1'),
            ],
        ]);
        $url = new Url('test_route_1');
        $url->setUrlGenerator($this->urlGenerator);
        $expected_link_markup = '<a href="/test-route-1">Test</a>';
        // Test ::generate().
        $this->assertSame($expected_link_markup, (string) $this->linkGenerator
            ->generate('Test', $url));
        $generated_link = $this->linkGenerator
            ->generate('Test', $url);
        $this->assertSame($expected_link_markup, (string) $generated_link->getGeneratedLink());
        $this->assertInstanceOf('\\Drupal\\Core\\Render\\BubbleableMetadata', $generated_link);
        // Test ::generateFromLink().
        $link = new Link('Test', $url);
        $this->assertSame($expected_link_markup, (string) $this->linkGenerator
            ->generateFromLink($link));
        $generated_link = $this->linkGenerator
            ->generateFromLink($link);
        $this->assertSame($expected_link_markup, (string) $generated_link->getGeneratedLink());
        $this->assertInstanceOf('\\Drupal\\Core\\Render\\BubbleableMetadata', $generated_link);
    }
    
    /**
     * Tests altering the URL object using hook_link_alter().
     *
     * @covers ::generate
     */
    public function testGenerateWithAlterHook() {
        $options = [
            'query' => [],
            'language' => NULL,
            'set_active_class' => FALSE,
            'absolute' => FALSE,
        ];
        $this->urlGenerator
            ->expects($this->any())
            ->method('generateFromRoute')
            ->willReturnMap([
            [
                'test_route_1',
                [],
                $options,
                TRUE,
                (new GeneratedUrl())->setGeneratedUrl('/test-route-1'),
            ],
            [
                'test_route_2',
                [],
                $options,
                TRUE,
                (new GeneratedUrl())->setGeneratedUrl('/test-route-2'),
            ],
        ]);
        $url = new Url('test_route_2');
        $url->setUrlGenerator($this->urlGenerator);
        $this->moduleHandler
            ->expects($this->atLeastOnce())
            ->method('alter')
            ->willReturnCallback(function ($hook, &$options) {
            $options['url'] = (new Url('test_route_1'))->setUrlGenerator($this->urlGenerator);
        });
        $expected_link_markup = '<a href="/test-route-1">Test</a>';
        $this->assertEquals($expected_link_markup, (string) $this->linkGenerator
            ->generate('Test', $url)
            ->getGeneratedLink());
    }
    
    /**
     * Tests whether rendering the same link twice works.
     *
     * This is a regression test for https://www.drupal.org/node/2842399.
     */
    public function testGenerateTwice() {
        $this->urlGenerator
            ->expects($this->any())
            ->method('generateFromRoute')
            ->willReturn((new GeneratedUrl())->setGeneratedUrl('/'));
        $url = Url::fromRoute('<front>', [], [
            'attributes' => [
                'class' => [
                    'foo',
                    'bar',
                ],
            ],
        ]);
        $url->setUrlGenerator($this->urlGenerator);
        $link = Link::fromTextAndUrl('text', $url);
        $link->setLinkGenerator($this->linkGenerator);
        $output = $link->toString() . $link->toString();
        $this->assertEquals('<a href="/" class="foo bar">text</a><a href="/" class="foo bar">text</a>', $output);
    }
    
    /**
     * Checks that a link with certain properties exists in a given HTML snippet.
     *
     * @param array $properties
     *   An associative array of link properties, with the following keys:
     *   - attributes: optional array of HTML attributes that should be present.
     *   - content: optional link content.
     * @param \Drupal\Component\Render\MarkupInterface $html
     *   The HTML to check.
     * @param int $count
     *   How many times the link should be present in the HTML. Defaults to 1.
     *
     * @internal
     */
    public static function assertLink(array $properties, MarkupInterface $html, int $count = 1) : void {
        // Provide default values.
        $properties += [
            'attributes' => [],
        ];
        // Create an XPath query that selects a link element.
        $query = '//a';
        // Append XPath predicates for the attributes and content text.
        $predicates = [];
        foreach ($properties['attributes'] as $attribute => $value) {
            $predicates[] = "@{$attribute}='{$value}'";
        }
        if (!empty($properties['content'])) {
            $predicates[] = "contains(.,'{$properties['content']}')";
        }
        if (!empty($predicates)) {
            $query .= '[' . implode(' and ', $predicates) . ']';
        }
        // Execute the query.
        $document = new \DOMDocument();
        $document->loadHTML($html);
        $xpath = new \DOMXPath($document);
        self::assertEquals($count, $xpath->query($query)->length);
    }
    
    /**
     * Checks that the given XPath query has no results in a given HTML snippet.
     *
     * @param string $query
     *   The XPath query to execute.
     * @param string $html
     *   The HTML snippet to check.
     *
     * @internal
     */
    protected function assertNoXPathResults(string $query, string $html) : void {
        $document = new \DOMDocument();
        $document->loadHTML($html);
        $xpath = new \DOMXPath($document);
        self::assertFalse((bool) $xpath->query($query)->length);
    }

}