ENGCOM-8173: Fix inability to place PayPal guest order when Automatic Assignment to Customer Group is enabled #25405

 - Merge Pull Request #25405 from xylodev/magento2:paypal-fix-for-customer-automatic-group-assignment
 - Merged commits:
   1. 594fc93
   2. fb299a0
   3. f898245
   4. 7f280cd

Author: magento-engcom-team

app/code/Magento/Quote/Observer/Frontend/Quote/Address/CollectTotalsObserver.php

@@ -5,7 +5,16 @@
  */
 namespace Magento\Quote\Observer\Frontend\Quote\Address;
 
+use Magento\Customer\Api\AddressRepositoryInterface;
+use Magento\Customer\Api\Data\CustomerInterfaceFactory;
+use Magento\Customer\Api\GroupManagementInterface;
+use Magento\Customer\Helper\Address;
+use Magento\Customer\Model\Session;
+use Magento\Customer\Model\Vat;
+use Magento\Framework\Event\Observer;
 use Magento\Framework\Event\ObserverInterface;
+use Magento\Quote\Api\Data\ShippingAssignmentInterface;
+use Magento\Quote\Model\Quote;
 
 /**
  * Handle customer VAT number on collect_totals_before event of quote address.
@@ -15,22 +24,22 @@
 class CollectTotalsObserver implements ObserverInterface
 {
     /**
-     * @var \Magento\Customer\Api\AddressRepositoryInterface
+     * @var AddressRepositoryInterface
      */
     private $addressRepository;
 
     /**
-     * @var \Magento\Customer\Model\Session
+     * @var Session
      */
     private $customerSession;
 
     /**
-     * @var \Magento\Customer\Helper\Address
+     * @var Address
      */
     protected $customerAddressHelper;
 
     /**
-     * @var \Magento\Customer\Model\Vat
+     * @var Vat
      */
     protected $customerVat;
 
@@ -40,36 +49,36 @@ class CollectTotalsObserver implements ObserverInterface
     protected $vatValidator;
 
     /**
-     * @var \Magento\Customer\Api\Data\CustomerInterfaceFactory
+     * @var CustomerInterfaceFactory
      */
     protected $customerDataFactory;
 
     /**
      * Group Management
      *
-     * @var \Magento\Customer\Api\GroupManagementInterface
+     * @var GroupManagementInterface
      */
     protected $groupManagement;
 
     /**
      * Initialize dependencies.
      *
-     * @param \Magento\Customer\Helper\Address $customerAddressHelper
-     * @param \Magento\Customer\Model\Vat $customerVat
+     * @param Address $customerAddressHelper
+     * @param Vat $customerVat
      * @param VatValidator $vatValidator
-     * @param \Magento\Customer\Api\Data\CustomerInterfaceFactory $customerDataFactory
-     * @param \Magento\Customer\Api\GroupManagementInterface $groupManagement
-     * @param \Magento\Customer\Api\AddressRepositoryInterface $addressRepository
-     * @param \Magento\Customer\Model\Session $customerSession
+     * @param CustomerInterfaceFactory $customerDataFactory
+     * @param GroupManagementInterface $groupManagement
+     * @param AddressRepositoryInterface $addressRepository
+     * @param Session $customerSession
      */
     public function __construct(
-        \Magento\Customer\Helper\Address $customerAddressHelper,
-        \Magento\Customer\Model\Vat $customerVat,
+        Address $customerAddressHelper,
+        Vat $customerVat,
         VatValidator $vatValidator,
-        \Magento\Customer\Api\Data\CustomerInterfaceFactory $customerDataFactory,
-        \Magento\Customer\Api\GroupManagementInterface $groupManagement,
-        \Magento\Customer\Api\AddressRepositoryInterface $addressRepository,
-        \Magento\Customer\Model\Session $customerSession
+        CustomerInterfaceFactory $customerDataFactory,
+        GroupManagementInterface $groupManagement,
+        AddressRepositoryInterface $addressRepository,
+        Session $customerSession
     ) {
         $this->customerVat = $customerVat;
         $this->customerAddressHelper = $customerAddressHelper;
@@ -83,25 +92,23 @@ public function __construct(
     /**
      * Handle customer VAT number if needed on collect_totals_before event of quote address
      *
-     * @param \Magento\Framework\Event\Observer $observer
+     * @param Observer $observer
      * @return void
      * @SuppressWarnings(PHPMD.CyclomaticComplexity)
      */
-    public function execute(\Magento\Framework\Event\Observer $observer)
+    public function execute(Observer $observer)
     {
-        /** @var \Magento\Quote\Api\Data\ShippingAssignmentInterface $shippingAssignment */
+        /** @var ShippingAssignmentInterface $shippingAssignment */
         $shippingAssignment = $observer->getShippingAssignment();
-        /** @var \Magento\Quote\Model\Quote $quote */
+        /** @var Quote $quote */
         $quote = $observer->getQuote();
-        /** @var \Magento\Quote\Model\Quote\Address $address */
+        /** @var Quote\Address $address */
         $address = $shippingAssignment->getShipping()->getAddress();
 
         $customer = $quote->getCustomer();
         $storeId = $customer->getStoreId();
 
-        if ($customer->getDisableAutoGroupChange()
-            || false == $this->vatValidator->isEnabled($address, $storeId)
-        ) {
+        if ($customer->getDisableAutoGroupChange() || !$this->vatValidator->isEnabled($address, $storeId)) {
             return;
         }
         $customerCountryCode = $address->getCountryId();
@@ -135,6 +142,7 @@ public function execute(\Magento\Framework\Event\Observer $observer)
             $quote->setCustomerGroupId($groupId);
             $this->customerSession->setCustomerGroupId($groupId);
             $customer->setGroupId($groupId);
+            $customer->setEmail($customer->getEmail() ?: $quote->getCustomerEmail());
             $quote->setCustomer($customer);
         }
     }

dev/tests/integration/testsuite/Magento/Paypal/Model/Express/CheckoutTest.php

@@ -17,34 +17,36 @@
 use Magento\Quote\Model\Quote\Address;
 use Magento\Quote\Model\ResourceModel\Quote\Collection;
 use Magento\TestFramework\Helper\Bootstrap;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
 
 /**
  * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
  */
-class CheckoutTest extends \PHPUnit\Framework\TestCase
+class CheckoutTest extends TestCase
 {
     /**
      * @var ObjectManagerInterface
      */
     private $objectManager;
 
     /**
-     * @var Info|\PHPUnit\Framework\MockObject\MockObject
+     * @var Info|MockObject
      */
     private $paypalInfo;
 
     /**
-     * @var Config|\PHPUnit\Framework\MockObject\MockObject
+     * @var Config|MockObject
      */
     private $paypalConfig;
 
     /**
-     * @var Factory|\PHPUnit\Framework\MockObject\MockObject
+     * @var Factory|MockObject
      */
     private $apiTypeFactory;
 
     /**
-     * @var Nvp|\PHPUnit\Framework\MockObject\MockObject
+     * @var Nvp|MockObject
      */
     private $api;
 
@@ -215,6 +217,28 @@ public function testPlaceGuestQuote()
         $this->assertNotEmpty($order->getShippingAddress());
     }
 
+    /**
+     * Place the order as guest when `Automatic Assignment to Customer Group` is enabled.
+     *
+     * @magentoDataFixture Magento/Paypal/_files/quote_express.php
+     * @magentoConfigFixture current_store customer/create_account/auto_group_assign 1
+     *
+     * @return void
+     */
+    public function testPlaceGuestQuoteAutomaticAssignmentEnabled(): void
+    {
+        $quote = $this->getFixtureQuote();
+        $quote->setCheckoutMethod(Onepage::METHOD_GUEST);
+        $quote->getShippingAddress()->setSameAsBilling(0);
+        $quote->setReservedOrderId(null);
+
+        $checkout = $this->getCheckout($quote);
+        $checkout->place('token');
+
+        $order = $checkout->getOrder();
+        $this->assertNotEmpty($order->getRealOrderId());
+    }
+
     /**
      * @param Quote $quote
      * @return Checkout
@@ -721,11 +745,11 @@ private function getFixtureQuote(): Quote
     /**
      * Adds countryFactory to a mock.
      *
-     * @param \PHPUnit\Framework\MockObject\MockObject $api
+     * @param MockObject $api
      * @return void
      * @throws \ReflectionException
      */
-    private function addCountryFactory(\PHPUnit\Framework\MockObject\MockObject $api): void
+    private function addCountryFactory(MockObject $api): void
     {
         $reflection = new \ReflectionClass($api);
         $property = $reflection->getProperty('_countryFactory');