MC-40678: Cart page subtotal shows wrong when we back from multishipping

Author: Viktor Kopin

app/code/Magento/Multishipping/Model/Cart/Controller/CartPlugin.php

@@ -73,7 +73,7 @@ public function beforeDispatch(Cart $subject, RequestInterface $request)
     {
         /** @var Quote $quote */
         $quote = $this->checkoutSession->getQuote();
-        if ($quote->isMultipleShippingAddresses() && $this->isCheckoutComplete()) {
+        if ($quote->isMultipleShippingAddresses()) {
             $this->disableMultishipping->execute($quote);
             foreach ($quote->getAllShippingAddresses() as $address) {
                 $quote->removeAddress($address->getId());
@@ -92,16 +92,6 @@ public function beforeDispatch(Cart $subject, RequestInterface $request)
         }
     }
 
-    /**
-     * Checks whether the checkout flow is complete
-     *
-     * @return bool
-     */
-    private function isCheckoutComplete() : bool
-    {
-        return (bool) ($this->checkoutSession->getStepData(State::STEP_SHIPPING)['is_complete'] ?? true);
-    }
-
     /**
      * Checks whether quote has virtual items
      *

app/code/Magento/Multishipping/Test/Mftf/Test/StorefrontProcessMultishippingCheckoutWhenCartPageIsOpenedInAnotherTabTest.xml

@@ -85,6 +85,12 @@
         </actionGroup>
         <switchToNextTab stepKey="switchToNextTab"/>
         <!-- Click 'Continue to Billing Information' and 'Go to Review Your Order' -->
+        <actionGroup ref="StorefrontGoToBillingInformationActionGroup" stepKey="redirectToSelectAddressAfterReset"/>
+        <seeOptionIsSelected selector="{{StorefrontCheckoutShippingMultipleAddressesSection.selectedMultipleShippingAddress('1')}}" userInput="{{US_Address_NY.street[1]}}" stepKey="checkAddressIsReset"/>
+        <actionGroup ref="StorefrontCheckoutShippingSelectMultipleAddressesActionGroup" stepKey="selectMultipleAddressesAfterReset">
+            <argument name="firstAddress" value="{{UK_Not_Default_Address.street[0]}}"/>
+            <argument name="secondAddress" value="{{US_Address_NY.street[1]}}"/>
+        </actionGroup>
         <actionGroup ref="StorefrontGoToBillingInformationActionGroup" stepKey="goToBillingInformation"/>
         <see selector="{{ShipmentFormSection.shippingAddress}}" userInput="{{US_Address_NY.city}}" stepKey="seeBillingAddress"/>
         <waitForElementVisible selector="{{StorefrontMultipleShippingMethodSection.goToReviewYourOrderButton}}" stepKey="waitForGoToReviewYourOrderVisible" />