fixed unit

Author: engcom-Charlie

app/code/Magento/Sales/Test/Unit/Block/Adminhtml/Order/Totals/TaxTest.php

@@ -129,6 +129,9 @@ public function testGetFullTaxInfoOrderWithoutTax(): void
             ->method('loadByOrder')
             ->with($orderMock)
             ->willReturnSelf();
+        $taxCollection->expects($this->once())
+            ->method('toArray')
+            ->willReturn(['items' => []]);
 
         $taxOrder = $this->createMock(TaxModel::class);
         $taxOrder->expects($this->once())