Now let’s understand how “ just runs” skips the real function call. If we skip the function’s execution successfully, “Hello World!” shouldn’t be added to the given list after the invocation. A function parameter can accept arguments of any type, including arguments that are functions. And then, we call the function and pass an empty MutableList to it. In this short post, well take a look at some of the special types in Kotlin. You can also use them in functions you write yourself.

Let’s create a service that requires two instances of our TestableService: class InjectTestService just runsĪs the test above shows, we stub the addHelloWorld() function using “ just runs“. Of course, we can add the open keyword to classes and methods that we want to mock. Most JVM mock libraries have problems with mocking or stubbing final classes. While this helps us write immutable code, it also causes some problems during testing.

It is possible to use MockK annotations to create all kind of mocks. In Kotlin, all classes and methods are final.

Kotlin any type