muzich/vendor/swiftmailer/tests/acceptance/Swift/MimePartAcceptanceTest.php

<?php

require_once 'swift_required.php';
require_once 'Swift/Mime/MimePartAcceptanceTest.php';

class Swift_MimePartAcceptanceTest extends Swift_Mime_MimePartAcceptanceTest
{
    protected function _createMimePart()
    {
        Swift_DependencyContainer::getInstance()
            ->register('properties.charset')->asValue(null);
        return Swift_MimePart::newInstance();
    }
}