added unit test assertions

Author: ilnytskyi

app/code/Magento/Tax/Test/Unit/Model/Sales/Total/Quote/ShippingTest.php

@@ -108,6 +108,7 @@ public function testCollectDoesNotCalculateTaxIfThereIsNoItemsRelatedToGivenAddr
     {
         $storeId = 1;
         $this->quoteMock->expects($this->once())->method('getStoreId')->willReturn($storeId);
+        $this->quoteMock->expects($this->never())->method('getShippingAddress');
 
         $addressMock = $this->getMockObject(Address::class, [
             'all_items' => [],
@@ -168,6 +169,7 @@ private function getMockObject($className, array $objectState)
 
     public function testFetch()
     {
+        $this->quoteMock->expects($this->never())->method('getShippingAddress');
         $value = 42;
         $total = new Total();
         $total->setShippingInclTax($value);
@@ -181,6 +183,8 @@ public function testFetch()
 
     public function testFetchWithZeroShipping()
     {
+        $this->quoteMock->expects($this->never())->method('getShippingAddress');
+
         $value = 0;
         $total = new Total();
         $total->setShippingInclTax($value);