RegistrationContext.php

<?php

use Behat\Behat\Context\Context;

namespace Context;

class RegistrationContext implements Context
{
    /**
     * @When I go to the registration page
     */
    public function iGoToTheRegistrationPage()
    {
        $this->visit('/inscription');
    }    

    /**
     * @When I register with :email as email
     * @When I register with :nickname as nickname     
     * @When I register with :password as password
     */
    public function iRegisterWith($email = 'foo@bar.com', $nickname = 'FooBar', $password = 'foobar1337')
    {
        $this->iGoToTheRegistrationPage();
        $this->fillField('register_email', $email);
        $this->fillField('register_person_nickname', $nickname);
        $this->fillField('register_plainPassword_first', $password);
        $this->fillField('register_plainPassword_second', $password);

        $this->pressButton('register_registerButton');
    }    

    /**
     * @When I register with an empty form
     */
    public function iRegisterWithAnEmptyForm()
    {
        $this->iRegisterWith('', '', '');
    }
}

$test = new Context();
$test->iGoToTheRegistrationPage();
$test->iRegisterWith('ever.zet@gmail.com');