function setupLanguageTests(languagesAndRoles) {
      langsFromContent = languagesAndRoles.map((langAndRole) => {
        return langAndRole.language;
      });

      languageButtons = filterButtons(languageMenu.childNodes,
          ['shaka-back-to-overflow-button', 'shaka-turn-captions-off-button']);

      languagesToButtons = mapChoicesToButtons(
          /* allButtons= */ languageButtons,
          /* choices= */ langsFromContent,
          /* modifier= */ getNativeName,
      );
    }
@param {!Array<shaka.extern.LanguageRole>} languagesAndRoles