With unit testing for your AEM application using JUnit4, you can utilise AEM Mocks library.
For example, as you are trying to mock the value returned by the @ValueMapValue annotation, you will need to build the context of an adaptable object. Once that adaptable object is constructed, you can adapt that adaptable object to the Sling Model (underTest). Also mocking the currentPage @ScriptVariable object can be done as easy as a simple line of code; @Mock private Page currentPage.
This seems like a mouthful. Take a look at this reference on how to write JUnit4 unit tests for sling models. This article provides code snippets and examples.