[Shop][Checkout] Prevent starting checkout with empty cart

features/checkout/prevent_starting_checkout_with_empty_cart.feature

@@ -0,0 +1,17 @@
+@checkout
+Feature: Prevent starting checkout with empty cart
+    In order to get back to shop after starting checkout with empty cart
+    As a Customer
+    I want to be able to add something to cart before entering checkout
+
+    Background:
+        Given the store operates on a single channel in "United States"
+        And the store has a product "PHP T-Shirt" priced at "$19.99"
+        And the store ships everywhere for free
+        And the store allows paying offline
+        And I am a logged in customer
+
+    @ui
+    Scenario: Being on shop home page after starting checkout with empty cart
+        Given I have tried to open checkout addressing page
+        Then I should be redirected to the homepage

src/Sylius/Behat/Context/Ui/CheckoutContext.php

@@ -169,6 +169,14 @@ final class CheckoutContext implements Context
         $this->addressPage->open();
     }
 
+    /**
+     * @Given I have tried to open checkout addressing page
+     */
+    public function iHaveTriedToOpenCheckoutAddressingPage()
+    {
+        $this->addressPage->tryToOpen();
+    }
+
     /**
      * @Given /^(this user) bought this product$/
      */

src/Sylius/Bundle/CoreBundle/Checkout/CheckoutResolver.php

@@ -83,6 +83,11 @@ final class CheckoutResolver implements EventSubscriberInterface
 
         /** @var OrderInterface $order */
         $order = $this->cartContext->getCart();
+
+        if ($order->isEmpty()) {
+            $event->setResponse(new RedirectResponse($this->urlGenerator->generate('sylius_shop_homepage')));
+        }
+
         $stateMachine = $this->stateMachineFactory->get($order, OrderCheckoutTransitions::GRAPH);
 
         if ($stateMachine->can($this->getRequestedTransition($request))) {
@@ -95,7 +100,7 @@ final class CheckoutResolver implements EventSubscriberInterface
             return;
         }
 
-        $event->setResponse(new RedirectResponse($this->urlGenerator->generate($order->getCheckoutState())));
+        $event->setResponse(new RedirectResponse($this->urlGenerator->generateForOrderCheckoutState($order)));
     }
 
     /**

src/Sylius/Bundle/CoreBundle/Checkout/CheckoutStateUrlGenerator.php

@@ -11,15 +11,15 @@
 
 namespace Sylius\Bundle\CoreBundle\Checkout;
 
+use Sylius\Component\Core\Model\OrderInterface;
 use Symfony\Component\Routing\Exception\RouteNotFoundException;
-use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
 use Symfony\Component\Routing\RequestContext;
 use Symfony\Component\Routing\RouterInterface;
 
 /**
  * @author Arkadiusz Krakowiak <arkadiusz.krakowiak@lakion.com>
  */
-final class CheckoutStateUrlGenerator implements UrlGeneratorInterface
+final class CheckoutStateUrlGenerator implements CheckoutStateUrlGeneratorInterface
 {
     /**
      * @var RouterInterface
@@ -44,13 +44,21 @@ final class CheckoutStateUrlGenerator implements UrlGeneratorInterface
     /**
      * {@inheritdoc}
      */
-    public function generate($name, $parameters = array(), $referenceType = self::ABSOLUTE_PATH)
+    public function generate($name, $parameters = [], $referenceType = self::ABSOLUTE_PATH)
     {
-        if (!isset($this->routeCollection[$name]['route'])) {
+        return $this->router->generate($name, $parameters, $referenceType);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function generateForOrderCheckoutState(OrderInterface $order, $parameters = [], $referenceType = self::ABSOLUTE_PATH)
+    {
+        if (!isset($this->routeCollection[$order->getCheckoutState()]['route'])) {
             throw new RouteNotFoundException();
         }
 
-        return $this->router->generate($this->routeCollection[$name]['route'], $parameters, $referenceType);
+        return $this->router->generate($this->routeCollection[$order->getCheckoutState()]['route'], $parameters, $referenceType);
     }
 
     /**

src/Sylius/Bundle/CoreBundle/Checkout/CheckoutStateUrlGeneratorInterface.php

@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * This file is part of the Sylius package.
+ *
+ * (c) Paweł Jędrzejewski
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Sylius\Bundle\CoreBundle\Checkout;
+
+use Sylius\Component\Core\Model\OrderInterface;
+use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
+
+/**
+ * @author Arkadiusz Krakowiak <arkadiusz.krakowiak@lakion.com>
+ */
+interface CheckoutStateUrlGeneratorInterface extends UrlGeneratorInterface
+{
+    /**
+     * @param OrderInterface $order
+     * @param array $parameters
+     * @param int $referenceType
+     *
+     * @return string
+     */
+    public function generateForOrderCheckoutState(OrderInterface $order, $parameters = [], $referenceType = self::ABSOLUTE_PATH);
+}

src/Sylius/Bundle/CoreBundle/spec/Checkout/CheckoutStateUrlGeneratorSpec.php

@@ -14,6 +14,8 @@ namespace spec\Sylius\Bundle\CoreBundle\Checkout;
 use PhpSpec\ObjectBehavior;
 use Prophecy\Argument;
 use Sylius\Bundle\CoreBundle\Checkout\CheckoutStateUrlGenerator;
+use Sylius\Bundle\CoreBundle\Checkout\CheckoutStateUrlGeneratorInterface;
+use Sylius\Component\Core\Model\OrderInterface;
 use Symfony\Component\Routing\Exception\RouteNotFoundException;
 use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
 use Symfony\Component\Routing\RouterInterface;
@@ -46,19 +48,36 @@ final class CheckoutStateUrlGeneratorSpec extends ObjectBehavior
         $this->shouldImplement(UrlGeneratorInterface::class);
     }
 
-    function it_generates_state_url(RouterInterface $router)
+    function it_is_a_checkout_state_url_generator()
     {
+        $this->shouldImplement(CheckoutStateUrlGeneratorInterface::class);
+    }
+
+    function it_generates_state_url(RouterInterface $router, OrderInterface $order)
+    {
+        $order->getCheckoutState()->willReturn('addressed');
+
         $router->generate('sylius_shop_checkout_select_shipping', [], UrlGeneratorInterface::ABSOLUTE_PATH)
             ->willReturn('/checkout/address')
         ;
 
-        $this->generate('addressed')->shouldReturn('/checkout/address');
+        $this->generateForOrderCheckoutState($order)->shouldReturn('/checkout/address');
     }
 
-    function it_throws_route_not_found_exception_if_there_is_no_route_for_given_state(RouterInterface $router)
+    function it_is_a_regular_url_generator(RouterInterface $router)
     {
+        $router->generate('route_name', [], UrlGeneratorInterface::ABSOLUTE_PATH)->willReturn('/some-route');
+
+        $this->generate('route_name')->shouldReturn('/some-route');
+    }
+
+    function it_throws_route_not_found_exception_if_there_is_no_route_for_given_state(
+        RouterInterface $router,
+        OrderInterface $order
+    ) {
+        $order->getCheckoutState()->willReturn('shipping_selected');
         $router->generate(Argument::any())->shouldNotBeCalled();
 
-        $this->shouldThrow(RouteNotFoundException::class)->during('generate', ['shipping_selected']);
+        $this->shouldThrow(RouteNotFoundException::class)->during('generateForOrderCheckoutState', [$order]);
     }
 }