eZ\Bundle\EzPublishRestBundle\Features\Context\SubContext\Authentication::createSession PHP Method

    public function createSession($login, $password)
    {
        $this->createRequest('post', '/user/sessions');
        $this->setHeaderWithObject('accept', 'Session');
        $this->setHeaderWithObject('content-type', 'SessionInput');
        $this->makeObject('SessionInput');
        $this->setFieldToValue('login', $login);
        $this->setFieldToValue('password', $password);
        $this->sendRequest();
        $this->userSession = $this->getResponseObject();
        if (!$this->userSession instanceof \eZ\Publish\Core\REST\Server\Values\UserSession) {
            if ($this->userSession instanceof \eZ\Publish\Core\REST\Client\Values\ErrorMessage) {
                $message = sprintf("Unexpected '%s' in HTTP request response: %s", $this->userSession->message, $this->userSession->description);
            } else {
                $message = false;
            }
            throw new \RuntimeException($message ?: 'UserSession value expected, got ' . get_class($this->userSession), 0, isset($exceptionValue) ? $exceptionValue : null);
        }
        $this->resetDriver();
        // apply session/csrf token to next request
        $this->restDriver->setHeader('cookie', "{$this->userSession->sessionName}={$this->userSession->sessionId}");
        $this->restDriver->setHeader('x-csrf-token', $this->userSession->csrfToken);
    }