[Backport]-issue-195196 Customer related values are NULL for guests converted to customers after checkout.

app/code/Magento/Checkout/Test/Mftf/Test/StorefrontGuestCheckoutTest.xml

@@ -73,7 +73,7 @@
         <click selector="{{OrdersGridSection.firstRow}}" stepKey="clickOrderRow"/>
         <waitForPageLoad stepKey="waitForOrderPageLoad"/>
         <see selector="{{OrderDetailsInformationSection.orderStatus}}" userInput="Pending" stepKey="seeAdminOrderStatus"/>
-        <see selector="{{OrderDetailsInformationSection.accountInformation}}" userInput="Guest" stepKey="seeAdminOrderGuest"/>
+        <see selector="{{OrderDetailsInformationSection.accountInformation}}" userInput="{{CustomerEntityOne.fullname}}" stepKey="seeAdminOrderGuest"/>
         <see selector="{{OrderDetailsInformationSection.accountInformation}}" userInput="{{CustomerEntityOne.email}}" stepKey="seeAdminOrderEmail"/>
         <see selector="{{OrderDetailsInformationSection.billingAddress}}" userInput="{{CustomerAddressSimple.street[0]}}" stepKey="seeAdminOrderBillingAddress"/>
         <see selector="{{OrderDetailsInformationSection.shippingAddress}}" userInput="{{CustomerAddressSimple.street[0]}}" stepKey="seeAdminOrderShippingAddress"/>

app/code/Magento/Customer/Test/Mftf/Data/CustomerData.xml

@@ -21,6 +21,7 @@
         <data key="firstname">John</data>
         <data key="lastname">Doe</data>
         <data key="middlename">S</data>
+        <data key="fullname">John Doe</data>
         <data key="password">pwdTest123!</data>
         <data key="prefix">Mr</data>
         <data key="suffix">Sr</data>

app/code/Magento/Quote/Model/QuoteManagement.php

@@ -25,6 +25,7 @@
 /**
  * Class QuoteManagement
  *
+ * @SuppressWarnings(PHPMD.CookieAndSessionMisuse)
  * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
  * @SuppressWarnings(PHPMD.TooManyFields)
  */
@@ -355,6 +356,13 @@ public function placeOrder($cartId, PaymentInterface $paymentMethod = null)
         if ($quote->getCheckoutMethod() === self::METHOD_GUEST) {
             $quote->setCustomerId(null);
             $quote->setCustomerEmail($quote->getBillingAddress()->getEmail());
+            if ($quote->getCustomerFirstname() === null && $quote->getCustomerLastname() === null) {
+                $quote->setCustomerFirstname($quote->getBillingAddress()->getFirstname());
+                $quote->setCustomerLastname($quote->getBillingAddress()->getLastname());
+                if ($quote->getCustomerMiddlename() === null) {
+                    $quote->setCustomerMiddlename($quote->getBillingAddress()->getMiddlename());
+                }
+            }
             $quote->setCustomerIsGuest(true);
             $quote->setCustomerGroupId(\Magento\Customer\Api\Data\GroupInterface::NOT_LOGGED_IN_ID);
         }

app/code/Magento/Quote/Test/Unit/Model/QuoteManagementTest.php

@@ -642,7 +642,7 @@ public function testPlaceOrderIfCustomerIsGuest()
 
         $addressMock = $this->createPartialMock(\Magento\Quote\Model\Quote\Address::class, ['getEmail']);
         $addressMock->expects($this->once())->method('getEmail')->willReturn($email);
-        $this->quoteMock->expects($this->once())->method('getBillingAddress')->with()->willReturn($addressMock);
+        $this->quoteMock->expects($this->any())->method('getBillingAddress')->with()->willReturn($addressMock);
 
         $this->quoteMock->expects($this->once())->method('setCustomerIsGuest')->with(true)->willReturnSelf();
         $this->quoteMock->expects($this->once())

dev/tests/integration/testsuite/Magento/Quote/Model/QuoteTest.php

@@ -131,6 +131,9 @@ public function testUpdateCustomerData()
             $this->assertContains($item, $actual);
         }
         $this->assertEquals('[email protected]', $quote->getCustomerEmail());
+        $this->assertEquals('Joe', $quote->getCustomerFirstname());
+        $this->assertEquals('Dou', $quote->getCustomerLastname());
+        $this->assertEquals('Ivan', $quote->getCustomerMiddlename());
     }
 
     /**