Let’s say we have a project in which we have the following classes:
We don’t yet have an implementation of the Runway interface (that will be created by another team), but we would like to test if our code creates a correct Plane object and passes it to the Runway. We’ll be using Mockito to mock the Runway implementation to test only the Airport class (so, write an actual unit test). I really like AssertJ so I’ll be using that one for assertions instead of usual JUnit assertions.
Let’s start with testing if plane departs correctly:
We now know that a plane departed, but we don’t yet know if that was the right plane. Let’s try comparing to the plane we expect:
The result is a failing test – not that we wouldn’t expect that.
There are two separate instances of Plane created here. While their fields are all the same, they are different objects and Mockito’s verify method checks that. Moreover, if we wanted to check only if a specific field of passed object has an expected value, we wouldn’t have an ability to check that with Mockito’s verify. There is a class called ArgumentCaptor though that can help us. Also, AssertJ has a neat method for comparing if all fields of two objects are the same:
The dish is ready to be served, enjoy.