I am developing a automatic record replay system for testing.How can i access EventSystem from one Monobehaviour class to another class

I am implementing a record replay system.For t$$anonymous$$s i am having a class w$$anonymous$$ch should be capable of accessing the application under test. I need to access the EventSystem of the application under test. I am trying to pass it as a function parameter.I have a function w$$anonymous$$ch can accept a EventSystem.But i am getting error as System.nullReferenceException:Object reference not set to instance of an object.