BlogPresenterUTest.kt

@RunWith(JUnit4::class)
class BlogPresenterUTest {

    lateinit var blogRepository : BlogRepository
    lateinit var blogView : BlogView
    lateinit var blogPresenter : BlogPresenter

    @Before @Throws fun setUp(){
        RxAndroidPlugins.setInitMainThreadSchedulerHandler({ Schedulers.trampoline()})
        MockitoAnnotations.initMocks(this)

        blogPresenter = BlogPresenter(blogRepository = blogRepository, view = blogView)
    }

    @Test fun testBlogsReturnsList() {
        val blogs = getMockedBlogs(12)
        `when`(blogRepository.blogs()).thenReturn(Observable.just(blogs))

        blogPresenter.blogs()
        
        // Verify view method is called
        verify(view).setBlogs(blogs)
    }
    
    @Test fun testBlogsReturnsError() {
        `when`(blogRepository.blogs()).thenReturn(Observable.error(NetworkErrorException()))

        blogPresenter.blogs()

        // View is never called
        verify(view, never()).setBlogs(any())
    }

    fun getMockedBlogs(count : Int) : List<Blog> {
        val blogs = ArrayList<Blog>()
       for (i in 0..count) {
           val blog = mock(Blog::class.java)
           blogs.add(blog)
       }
        return blogs
    }

}