Blind vision for integration testing

gistfile1.java

@RunWith(JUnit4.class)
// Mockito + Spring integration/ use native @InjectMocks of mockito
@EnableMockedBean
// Spring MVC test configuration
@ContextConfiguration
@TestExecutionListeners({ DependencyInjectionTestExecutionListener.class,
        DirtiesContextTestExecutionListener.class,
        TransactionalTestExecutionListener.class,
        // DBUnit & Spring integration
        DbUnitTestExecutionListener.class })
// PowerMock
@PrepareForTest( { CustomUtil.class })
class GuineaPigResourceTests {

    // Assumption is that all these would hook into the lifecycle in the order in which these are specified
    // All these rules might needs to be collated in some form
    // Does not exist yet as for as I know
    @Rule
    NestedRunner nestedRunner = new NestedRunner();

    // Spring rules, exist in > 4.2
    @ClassRule
    static SpringClassRule SPRING_CLASS_RULE = new SpringClassRule();
    @Rule
    SpringMethodRule springMethodRule = new SpringMethodRule();

    // Does not exist yet as for as I know
    @Rule
    JunitParamsRunner junitParamsRunner = new JunitParamsRunner();

    // Does not exist yet as for as I know
    @Rule
    AssumesRunner assumesRunner = new AssumesRunner();

    // Exists in the latest beta of Mockito
    @Rule
    MockitoRule rule = MockitoJUnit.rule();
    // Already present
    @Rule
    PowerMockRule rule = new PowerMockRule();

    // Global vars
    // This mocked bean is already injected into GuineaPigService by the therore-spring-mockito library, whcih you can use to set expectations
    @MockedBean
    private EmailService emailService;

    @Resource
    private WebApplicationContext webApplicationContext;
    private MockMvc mockMvc;

    @Before
    void setUp() {
        mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext).build();
    }

    public class AddNewGuineaPig {
        @Before
        public void setup() {}

        @Test
        @Params(method = "validGuineaPigsProvider")
        void withValidValues_ShouldSave(GuineaPig guineaPig) {
            // we can even capture this argument using arguments captor and verify at the end
            when(emailService.send(anyObject()));
            when(CustomUtil.validateImage(ayString())).thenReturn(true); // power mockito

            mockMvc.perform(
                post("/")
                .content(guineaPig)
                .accepts(MediaType.APPLICATION_JSON)..
            )
            .andExpect(status().isOk())
            .andExpect(jsonPath("$.id", is(notNull())))
            .andExpect(jsonPath("$.name", is(guineaPig.getName())));

            // we may want to do a get on the new id and verify

            // Mockito verify
            verify(emailService.times(1));
            verify(validateImage()).times(1);
        }

        @Test
        // This test only makes sense after the save is successful, if its not succeeding lets skip this test altogeather
        @Assumes(method = "withValidValues_ShouldSave")
        void afterSave_EmailMessageHasCorrectSender() {
            // do additional cerifications
        }

        @Test
        @Params(method = "invalidGuineaPigsProvider")
        void withInvalidData_ShouldReturnUnProcessableEntity(GuineaPig guineaPig) {
            mockMvc.perform(
                    post("/")
                    .content(guineaPig)
                    .accepts(MediaType.APPLICATION_JSON)
            )
            .andExpect(status().is422());

            // Mockito verify that email is not sent
            verify(emailService.none());
        }

        @Test
        // DBUnit to populate some existing guinnea pigs
        @DatabaseSetup("GuineaPigs.xml")
        void withNonUniqueProperty_ShouldReturnUnProcessableEntity() {
            GuineaPig guineaPigWithDuplicateLicenseNumber = new GuineaPig.Builder()....build();

            mockMvc.perform(
                    post("/")
                    .content(guineaPigWithDuplicateLicenseNumber)
                    .accepts(MediaType.APPLICATION_JSON)
            )
            .andExpect(status().is422());

            // Mockito verify that email is not sent
            verify(emailService.none());
        }

        private GuineaPig[] validGuineaPigsProvider() {
            // or read from the file
            return new GuineaPig[] {
                    new GuineaPig.Builder().name("Name").breed("Breed").description("Desc").build(),
                    new GuineaPig.Builder().name("SomeOtherName").breed("Breed").description("Desc").build()
            };
        }

        private GuineaPig[] invalidGuineaPigsProvider() {
            // or read from the file
            return new GuineaPig[] {
                    new GuineaPig.Builder().name("").breed("Breed").description("Desc").build(),
                    new GuineaPig.Builder().name("Toooooooooooooooooooo Longggggggggg").breed("Breed").description("Desc").build()
            };
        }
    }
}

@RestController
@RequestMapping(consumes=MediaType.APPLICATION_JSON_VALUE, produces=MediaType.APPLICATION_JSON_VALUE)
class GuineaPigResource {
    @Autowired
    GuineaPigService guineaPigService;

    @RequestMapping(method=POST)
    GuineaPig save(GuineaPig pig) {
        return guineaPigService.save(pig);
    }
}

interface GuineaPigService {
    GuineaPig save(GuineaPig pig);
}

class GuineaPigServiceImpl implements GuineaPigService {
    @Autowired
    EmailService emailService;

    GuineaPig save(GuineaPig pig) {
        // Save using DAO
        // Storing the image in db is clearly a bad idea, this is here to illustrate the example
        CustomUtil.validateImage(pig.imageAsBase64);
        // construct emailMessage
        emailService.send(emailMessage);
    }
}

interface EmailService {
    void send(Message message);
}

class SendMailEmailService implements EmailService {
    void send(Message message) {
        // send using SendMail service
    }
}

@Builder
@AllArgsConstructor
class GuineaPig {
    // name validation rules
    // 1. name length must be between 2-10 chars
    // 2. name must be alphabets only
    // 3. other rules
    String name;
    String uniquePropery;
    String breed;
    String image;
    String description; // optional
}

class CustomUtil {
    private CustomUtil() {}
    static void validateImage() {
        // has constaints like running in a specific env/takes a long time to compute
    }
}