ACP2E-3885: is_available attribute in CartItemInterface returns false even when salable stock is high

Author: soklymeach

app/code/Magento/QuoteGraphQl/Model/CartItem/ProductStock.php

@@ -63,9 +63,6 @@ public function __construct(
      */
     public function isProductAvailable(Item $cartItem): bool
     {
-        if (!$cartItem->getQtyToAdd()) {
-            return false;
-        }
         $requestedQty = $cartItem->getQtyToAdd() ?? $cartItem->getQty();
         $previousQty = $cartItem->getPreviousQty() ?? 0;
 

app/code/Magento/QuoteGraphQl/Test/Unit/Model/CartItem/ProductStockTest.php

@@ -82,21 +82,6 @@ protected function setUp(): void
         );
     }
 
-    /**
-     * Test isProductAvailable() without quantity to add
-     */
-    public function testIsProductAvailableWithoutQtyToAdd(): void
-    {
-        $cartItemMock = $this->getMockBuilder(Item::class)
-            ->addMethods(['getQtyToAdd'])
-            ->disableOriginalConstructor()
-            ->getMock();
-        $cartItemMock->expects($this->once())
-            ->method('getQtyToAdd')
-            ->willReturn(null);
-        $this->assertFalse($this->productStock->isProductAvailable($cartItemMock));
-    }
-
     /**
      * Test isProductAvailable() for a simple product with sufficient stock
      */
@@ -113,7 +98,7 @@ public function testIsProductAvailableForSimpleProductWithStock(): void
             ->disableOriginalConstructor()
             ->addMethods(['getHasError'])
             ->getMockForAbstractClass();
-        $cartItemMock->expects($this->exactly(2))
+        $cartItemMock->expects($this->once())
             ->method('getQtyToAdd')
             ->willReturn(2);
         $cartItemMock->expects($this->once())
@@ -164,7 +149,7 @@ public function testIsProductAvailableForSimpleProductWithoutStock(): void
             ->disableOriginalConstructor()
             ->addMethods(['getHasError'])
             ->getMockForAbstractClass();
-        $cartItemMock->expects($this->exactly(2))
+        $cartItemMock->expects($this->once())
             ->method('getQtyToAdd')
             ->willReturn(5);
         $cartItemMock->expects($this->once())