Codeception\Module\WPDb::useTheme PHP Method

    public function useTheme($stylesheet, $template = null, $themeName = null)
    {
        if (!is_string($stylesheet)) {
            throw new \InvalidArgumentException('Stylesheet must be a string');
        }
        if (!(is_string($template) || is_null($template))) {
            throw new \InvalidArgumentException('Template must either be a string or be null.');
        }
        if (!(is_string($themeName) || is_null($themeName))) {
            throw new \InvalidArgumentException('Current Theme must either be a string or be null.');
        }
        $template = $template ?: $stylesheet;
        $themeName = $themeName ?: ucwords($stylesheet, " _");
        $this->haveOptionInDatabase('stylesheet', $stylesheet);
        $this->haveOptionInDatabase('template', $template);
        $this->haveOptionInDatabase('current_theme', $themeName);
        $this->stylesheet = $stylesheet;
        $this->menus[$stylesheet] = empty($this->menus[$stylesheet]) ? [] : $this->menus[$stylesheet];
    }