<form method="POST">
    <h3>Editing: EmailHeaderSame.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier &lt;fabien@symfony.com&gt;
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Mime\Test\Constraint;

use PHPUnit\Framework\Constraint\Constraint;
use Symfony\Component\Mime\Header\UnstructuredHeader;
use Symfony\Component\Mime\RawMessage;

final class EmailHeaderSame extends Constraint
{
    private $headerName;
    private $expectedValue;

    public function __construct(string $headerName, string $expectedValue)
    {
        $this-&gt;headerName = $headerName;
        $this-&gt;expectedValue = $expectedValue;
    }

    /**
     * {@inheritdoc}
     */
    public function toString(): string
    {
        return sprintf('has header &quot;%s&quot; with value &quot;%s&quot;', $this-&gt;headerName, $this-&gt;expectedValue);
    }

    /**
     * @param RawMessage $message
     *
     * {@inheritdoc}
     */
    protected function matches($message): bool
    {
        if (RawMessage::class === \get_class($message)) {
            throw new \LogicException('Unable to test a message header on a RawMessage instance.');
        }

        return $this-&gt;expectedValue === $this-&gt;getHeaderValue($message);
    }

    /**
     * @param RawMessage $message
     *
     * {@inheritdoc}
     */
    protected function failureDescription($message): string
    {
        return sprintf('the Email %s (value is %s)', $this-&gt;toString(), $this-&gt;getHeaderValue($message) ?? 'null');
    }

    private function getHeaderValue($message): ?string
    {
        if (null === $header = $message-&gt;getHeaders()-&gt;get($this-&gt;headerName)) {
            return null;
        }

        return $header instanceof UnstructuredHeader ? $header-&gt;getValue() : $header-&gt;getBodyAsString();
    }
}
</textarea><br>
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