AddressBookTest.kt

@RunWith(JMockit::class)
class AddressBookTest {

    @Injectable
    private lateinit var addressBookRepository: AddressBookRepository
    @Tested
    private lateinit var addressBook: AddressBook

    @Test
    fun retrieveAddressByIdTest() {

        object : Expectations() {
            init {
                // Instruct mocks
                addressBookRepository.findById(1)
                result = Address(1)
            }
        }

        val address = addressBook.getAddressById(1)
        Assert.assertNotNull(address)

        object : Verifications() {
            init {
                // Verify behaviour
                addressBookRepository.findById(1)
                times = 1
            }
        }
    }
}