Spring Boot Mockito Support

External

• https://www.baeldung.com/injecting-mocks-in-spring
• https://spring.io/blog/2016/04/15/testing-improvements-in-spring-boot-1-4#mocking-and-spying

Internal

• Spring Boot Testing Concepts
• Mockito

Overview

Spring Boot has built-in Mockito support and no additional dependencies are required in the Gradle build.gradle file to use Mockito mocks. This article describes the minimal amount of steps to inject Mockito mocks in tests, alongside whatever components and real JPA repositories the application uses. Note that a H2-based JPA repository is better than a Mockito mock, because it tests the real persistence logic.

@MockBean

The org.springframework.boot.test.mock.mockito.MockBean annotation injects Mockito mocks built around whatever component is specified in the test. Using @MockBean is the key to easily using mocks from Spring Boot unit tests.

Note that mocks will be automatically reset across tests.

Dependencies

dependencies {
  ...
  testImplementation 'org.springframework.boot:spring-boot-starter-test' // no special Mockito dependency is necessary
}

Example

@RunWith(SpringRunner.class)
@SpringBootTest
public class SomeTest {

    @Autowired
    private TestRestTemplate restTemplate;

    @MockBean
    private SomeService someService;

    @Before
    public void setup() {

        // this stubs behavior
        given(someService.getSomething("blah")).willReturn(new Something("blah"));
    }

    @Test
    public void test() {

        restTemplate.getForEntity("/{username}/something, String.class, "blue");
    }
}