MAGETWO-97396: Tax applied on child product is based on Tax Class of parent product

Author: serhii-balko

app/code/Magento/ConfigurableProduct/Test/Unit/Plugin/Tax/Model/Sales/Total/Quote/CommonTaxCollectorTest.php

@@ -78,7 +78,7 @@ public function testAfterMapItem()
 
         /* @var TaxClassKeyInterface|MockObject $taxClassObjectMock */
         $taxClassObjectMock = $this->createMock(TaxClassKeyInterface::class);
-        $taxClassObjectMock->method('setValue')->with($childTaxClassId);
+        $taxClassObjectMock->expects($this->once())->method('setValue')->with($childTaxClassId);
 
         /* @var QuoteDetailsItemInterface|MockObject $quoteDetailsItemMock */
         $quoteDetailsItemMock = $this->createMock(QuoteDetailsItemInterface::class);