gridPoolMock = $this->getMockBuilder(\Magento\Sales\Model\ResourceModel\GridPool::class) ->disableOriginalConstructor() ->getMock(); $this->eventObserverMock = $this->getMockBuilder(\Magento\Framework\Event\Observer::class) ->disableOriginalConstructor() ->setMethods(['getOrderId']) ->getMock(); $this->observer = new \Magento\Sales\Observer\GridProcessAddressChange($this->gridPoolMock); } public function testGridsReindex() { $this->eventObserverMock->expects($this->once()) ->method('getOrderId') ->willReturn(100500); $this->gridPoolMock->expects($this->once()) ->method('refreshByOrderId') ->with(100500); $this->assertNull($this->observer->execute($this->eventObserverMock)); } }