Click on a leaflet map icon in behat using a custom assumption

gistfile1.txt

  // Leaflet icons don't haave ids (at least the ones I'm using). Here we can click them by the z-index which is
  // the only unique id.
  
    /**
     * Click on map icon as identified by its z-index.
     *
     * @Given /^I click map icon number "([^"]*)"$/
     */
    public function iClickMapIcon($num) {
        $session = $this->getSession();
        $element = $session->getPage()->find(
            'xpath',
            $session->getSelectorsHandler()->selectorToXpath('xpath', '//img[contains(@style,"z-index: ' . $num . '")]')

        );
        if (null === $element) {
            throw new \InvalidArgumentException(sprintf('Cannot find map icon: "%s"', $num));
        }
        $element->click();
    }