尝试使用Selenium运行behat时，继续发生致命错误

Question

I have been trying to figure this out for 3 hours, and can't seem to understand why this is not working. My selenium server starts up fine.

When I run behat using selenium I keep getting the following error on my terminal

 Fatal error: Call to a member function open() on null (Behat\Testwork\Call\Exception\FatalThrowableError)

I am have no idea what this error message means. If someone can please help me figure this out I would really appreciate it.

Here below is my features context code where the issue is happening

use Behat\Behat\Tester\Exception\PendingException;
use Behat\Behat\Context\Context;
use Behat\Behat\Context\SnippetAcceptingContext;
use Behat\Gherkin\Node\PyStringNode;
use Behat\Gherkin\Node\TableNode;
use Behat\MinkExtension\Context\MinkContext;
use Behat\Mink\Driver\Selenium2Driver;

/**
 * Defines application features from the specific context.
 */
class FeatureContext extends MinkContext implements Context, SnippetAcceptingContext
{

    public  $session;

    public function __construct()
    {


        $driver = new \Behat\Mink\Driver\Selenium2Driver('firefox');
        $this->session = new \Behat\Mink\Session($driver);
    }



}

Answer 1

Do something like below:

class FeatureContext extends MinkContext
{
    public function __construct()
    {
        // Don't do anything with session or driver here
    }

    /**
     * @Then /^I need selenium driver for this step$/
     */
    public function iNeedSeleniumDriverForThisStep()
    {
        $driver = $this->getSession()->getDriver();

        if (!$driver instanceof Selenium2Driver) {
            throw new UnsupportedDriverActionException('Selenium2Driver not installed.');

            return;
        }

        // ......
        // ......
        // Do whatever you want
    }
}

Example behat.yml

default:
    context:
        class: FeatureContext
    extensions:
        Behat\Symfony2Extension\Extension:
            mink_driver: true
            kernel:
                env: test
                debug: true
        Behat\MinkExtension\Extension:
            base_url: 'http://symfony.local/app_test.php/'
            files_path: %behat.paths.base%/build/dummy/
            javascript_session: selenium2
            browser_name: firefox
            goutte: ~
            selenium2: ~
    paths:
        features: %behat.paths.base%/src
        bootstrap: %behat.paths.features%/Context

Also search for Selenium2Driver and selenium keyword in this site: http://www.inanzzz.com/index.php/posts/behat