mageekguy\atoum\asserters\utf8String::startWith PHP Метод

    public function startWith($fragment, $failMessage = null)
    {
        if (mb_strpos($this->valueIsSet()->value, $fragment, 0, 'UTF-8') === 0) {
            $this->pass();
        } else {
            $this->fail($failMessage ?: $this->_('%s does not start with %s', $this, $fragment));
        }
        return $this;
    }