Get the content of given element with ID

class FeatureContext extends MinkContext
{
    /**
     * Get content of element with the provided css id
     *
     * @Then /^The content of the element with id "([^"]*)" equals to "([^"]*)"$/
     *
     * @param $elementId ID attribute of an element
     * @param $content Content
     * @throws \InvalidArgumentException
     */
    public function contentsAreEqual($elementId, $content)
    {
        $session = $this->getSession();
        $page = $session->getPage();

        $element = $page->findById($elementId);

        if (null === $element) {
            throw new \InvalidArgumentException(sprintf('Could not evaluate CSS: "%s"', $elementId));
        }

	$element_content = $element->getText();

	if ($element_content == $content) {
	    $element->click();
	}

        throw new \InvalidArgumentException(sprintf('Could not evaluate CSS content: "%s"', $content));
    }
}