8000 [WebLink] Add class to parse Link headers from HTTP responses · symfony/symfony@5a7a0d4 · GitHub
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[WebLink] Add class to parse Link headers from HTTP responses
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    ‎src/Symfony/Component/WebLink/CHANGELOG.md

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    CHANGELOG
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    =========
    33

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    7.4.0
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    -----
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    * Add HttpHeaderParser to parse Link headers from HTTP responses
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    49
    4.4.0
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    -----
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    ‎src/Symfony/Component/WebLink/HttpHeaderParser.php

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    <?php
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    /*
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    * This file is part of the Symfony package.
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    *
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    * (c) Fabien Potencier <fabien@symfony.com>
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    *
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    * For the full copyright and license information, please view the LICENSE
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    * file that was distributed with this source code.
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    */
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    namespace Symfony\Component\WebLink;
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    /**
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    * Parse a list of HTTP Link headers into a list of Link instances.
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    *
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    * @see https://tools.ietf.org/html/rfc5988
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    *
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    * @author Jérôme Tamarelle <jerome@tamarelle.net>
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    */
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    final class HttpHeaderParser
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    {
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    // Regex to match each link entry: <...>; param1=...; param2=...
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    private const LINK_PATTERN = '/<([^>]*)>\s*((?:\s*;\s*[a-zA-Z0-9\-_]+(?:\s*=\s*(?:"(?:[^"\\\\]|\\\\.)*"|[^";,\s]+))?)*)/';
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    // Regex to match parameters: ; key[=value]
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    private const PARAM_PATTERN = '/;\s*([a-zA-Z0-9\-_]+)(?:\s*=\s*(?:"((?:[^"\\\\]|\\\\.)*)"|([^";,\s]+)))?/';
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    /**
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    * @param string|string[] $headers Value of the "Link" HTTP header
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    */
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    public function parse(string|array $headers): GenericLinkProvider
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    {
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    $headerString = is_array($headers) ? implode(',', $headers) : $headers;
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    $links = new GenericLinkProvider();
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    if (!preg_match_all(self::LINK_PATTERN, $headerString, $matches, PREG_SET_ORDER)) {
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    return $links;
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    }
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    foreach ($matches as $match) {
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    $href = $match[1];
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    $paramsString = $match[2];
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    $params = [];
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    if (preg_match_all(self::PARAM_PATTERN, $paramsString, $paramMatches, PREG_SET_ORDER)) {
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    foreach ($paramMatches as $pm) {
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    $key = $pm[1];
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    if (isset($pm[2]) && $pm[2] !== '') {
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    // Quoted value, unescape quotes
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    $value = stripcslashes($pm[2]);
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    } elseif (isset($pm[3]) && $pm[3] !== '') {
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    $value = $pm[3];
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    } else {
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    $value = true;
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    }
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    // Handle multiple attributes with same name
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    if (isset($params[$key])) {
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    if (!is_array($params[$key])) {
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    $params[$key] = [$params[$key]];
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    }
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    $params[$key][] = $value;
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    } else {
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    $params[$key] = $value;
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    }
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    }
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    }
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    if (!isset($params['rel'])) {
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    continue;
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    }
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    $rels = preg_split('/\s+/', trim($params['rel']));
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    unset($params['rel']);
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    $link = new Link(array_shift($rels), $href);
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    foreach ($rels as $r) {
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    $link = $link->withRel($r);
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    }
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    foreach ($params as $k => $v) {
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    $link = $link->withAttribute($k, $v);
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    }
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    $links = $links->withLink($link);
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    }
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    return $links;
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    }
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    }
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    ‎src/Symfony/Component/WebLink/Link.php

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    @@ -180,6 +180,11 @@ public function getAttributes(): array
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    return $this->attributes;
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    }
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    public function getAttribute(string $attribute): string|\Stringable|int|float|bool|array|null
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    {
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    return $this->attributes[$attribute] ?? null;
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    }
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    public function withHref(string|\Stringable $href): static
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    {
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    $that = clone $this;

    ‎src/Symfony/Component/WebLink/Tests/HttpHeaderParserTest.php

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    <?php
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    namespace Symfony\Component\WebLink\Tests;
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    use PHPUnit\Framework\TestCase;
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    use Symfony\Component\WebLink\HttpHeaderParser;
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    class HttpHeaderParserTest extends TestCase
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    {
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    public function testParse()
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    {
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    $parser = new HttpHeaderParser();
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    $header = [
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    '</1>; rel="prerender",</2>; rel="dns-prefetch"; pr="0.7",</3>; rel="preload"; as="script"',
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    '</4>; rel="preload"; as="image"; nopush,</5>; rel="alternate next"; hreflang="fr"; hreflang="de"; title="Hello"'
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    ];
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    $provider = $parser->parse($header);
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    $links = $provider->getLinks();
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    $this->assertCount(5, $links);
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    $this->assertSame(['prerender'], $links[0]->getRels());
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    $this->assertSame('/1', $links[0]->getHref());
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    $this->assertSame(null, $links[0]->getAttribute('rel'));
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    $this->assertSame(['dns-prefetch'], $links[1]->getRels());
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    $this->assertSame('/2', $links[1]->getHref());
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    $this->assertSame('0.7', $links[1]->getAttribute('pr'));
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    $this->assertSame(['preload'], $links[2]->getRels());
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    $this->assertSame('/3', $links[2]->getHref());
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    $this->assertSame('script', $links[2]->getAttribute('as'));
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    $this->assertSame(null, $links[2]->getAttribute('nopush'));
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    $this->assertSame(['preload'], $links[3]->getRels());
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    $this->assertSame('/4', $links[3]->getHref());
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    $this->assertSame('image', $links[3]->getAttribute('as'));
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    $this->assertSame(true, $links[3]->getAttribute('nopush'));
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    $this->assertSame(['alternate', 'next'], $links[4]->getRels());
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    $this->assertSame('/5', $links[4]->getHref());
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    $this->assertSame(['fr', 'de'], $links[4]->getAttribute('hreflang'));
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    $this->assertSame('Hello', $links[4]->getAttribute('title'));
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    }
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    public function testParseEmpty()
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    {
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    $parser = new HttpHeaderParser();
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    $provider = $parser->parse('');
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    $this->assertCount(0, $provider->getLinks());
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    }
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    /**
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    * @dataProvider provideHeaderParsingCases
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    */
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    public function testParseVariousAttributes($header, $expectedAttributes)
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    {
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    $parser = new HttpHeaderParser();
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    $links = $parser->parse($header)->getLinks();
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    $this->assertCount(1, $links);
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    $this->assertSame(['alternate'], $links[0]->getRels());
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    $this->assertSame('/foo', $links[0]->getHref());
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    $this->assertSame($expectedAttributes, $links[0]->getAttributes());
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    }
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    public static function provideHeaderParsingCases()
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    {
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    return [
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    'double_quotes_in_attribute_value' => [
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    '</foo>; rel="alternate"; title="\"escape me\" \"already escaped\" \"\"\""',
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    ['title' => '"escape me" "already escaped" """'],
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    ],
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    'unquoted_attribute_value' => [
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    '</foo>; rel=alternate; type=text/html',
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    ['type' => 'text/html'],
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    ],
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    'attribute_with_punctuation' => [
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    '</foo>; rel="alternate"; title="hello, world; test:case"',
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    ['title' => 'hello, world; test:case'],
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    ],
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    ];
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    }
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    }

    ‎src/Symfony/Component/WebLink/Tests/LinkTest.php

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    $this->assertContains('next', $link->getRels());
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    $this->assertArrayHasKey('me', $link->getAttributes());
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    $this->assertEquals('you', $link->getAttributes()['me']);
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    $this->assertEquals('you', $link->getAttribute('me'));
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    }
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    public function testCanRemoveValues()
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    $this->assertEquals('http://www.google.com', $link->getHref());
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    $this->assertFalse(\in_array('next', $link->getRels(), true));
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    $this->assertArrayNotHasKey('me', $link->getAttributes());
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    $this->assertNull($link->getAttribute('me'));
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    }
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    public function testMultipleRels()

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