lateinit property mock object has not been initialized

Question

I'm trying to initialize (by mocking) two objects with the annotation @MockBean

It seems only to work if i call the method mock(className), but since i want to use the mocked class on multiple methods i don't want to keep repeating the same code in my test methods.

This is my test class:

@RunWith(MockitoJUnitRunner::class)
class WordServiceTest {

    @MockBean
    lateinit var wordRepositoryMock: WordRepository

    @MockBean
    private lateinit var wordMapperMock: WordMapper

    @Test
    fun findAllTest() {
        // Error: lateinit property wordRepositoryMock has not been initialized
        val wordService = WordService(wordRepositoryMock, wordMapperMock)
        `when`(wordRepositoryMock.findAll()).thenReturn(listOf(
                WordEntity(UUID.randomUUID(), "xxx"),
                WordEntity(UUID.randomUUID(), "xxx")))
        assertEquals(2, wordService.findAll().size)
    }

    @Test
    fun wordExistsTest() {
        // This works fine
        val wordRepositoryMock = mock(WordRepository::class.java)
        val wordMapperMock = mock(WordMapper::class.java)
        val wordService = WordService(wordRepositoryMock, wordMapperMock)
        val word = "xxx"
        `when`(wordRepositoryMock.existsWordEntityByName(word)).thenReturn(true)
        assertEquals(true, wordService.wordExists(word))
    }
}

I don't want to use the Spring Boot @Autowired annotation because my spring application requires contexts which i don't want to load.

The error i'm getting:

lateinit property wordRepositoryMock has not been initialized
kotlin.UninitializedPropertyAccessException: lateinit property wordRepositoryMock has not been initialized

Dependencies:

dependencies {
    ...
    testImplementation("org.springframework.security:spring-security-test")
    testImplementation ('org.springframework.boot:spring-boot-starter-test') 
    testImplementation("org.junit.jupiter:junit-jupiter:5.6.2")
    testImplementation "org.junit.jupiter:junit-jupiter-params:5.5.2"
    testImplementation "org.junit.jupiter:junit-jupiter-api:5.6.2"
    testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:5.6.2"
    testImplementation("io.rest-assured:spring-mock-mvc:4.0.0")
    testImplementation("io.mockk:mockk:1.9.3")
    testImplementation "org.testcontainers:postgresql:1.11.3"
    testImplementation "org.springframework.kafka:spring-kafka-test:2.2.7.RELEASE"
    runtimeOnly('org.postgresql:postgresql')
    developmentOnly 'org.springframework.boot:spring-boot-devtools'
    testImplementation "org.mockito:mockito-junit-jupiter:3.3.3"
}

Answer 1

MockitoJUnitRunner works with the @Mock annotation.

@MockBean is coming from Spring so you need to use the @SpringRunner.

However, it looks like your examples don't need Spring, so you can switch to @Mock:

@RunWith(MockitoJUnitRunner::class)
class WordServiceTest {

    @Mock
    private lateinit var wordRepositoryMock: WordRepository

    @Mock
    private lateinit var wordMapperMock: WordMapper
}

There's a further improvement you could make if you upgraded to Junit5 (I only tested it in Junit5). Constructor arguments are a good alternative to lateinit:

@ExtendWith(MockitoExtension::class)
class WordServiceTest(
    @Mock val wordRepositoryMock: WordRepository,
    @Mock val wordMapperMock: WordMapper
) {

}

Answer 2

For the ones coming because initMocks(this) is deprecated, I noticed there's a newer function that does the same:

@BeforeEach
fun setUp() {
    MockitoAnnotations.openMocks(this)
        ....
}