dataContainerMock = $this->createPartialMock(\Magento\Framework\Event\Config\Data::class, ['get']); $this->config = new Config($this->dataContainerMock); } public function testGetObservers() { $eventName = 'some_event'; $observers = ['observer1', 'observer3']; $this->dataContainerMock->expects($this->once()) ->method('get') ->with($eventName, $this->equalTo([])) ->will($this->returnValue($observers)); $result = $this->config->getObservers($eventName); $this->assertEquals($observers, $result); } }