How to use @SpringBootTest class mockbean in test class?

Question

@SpringBootTest(classes = TestConfig.class)
class ServiceIntegTest {

}

class TestConfig {

@MockBean
RandomExecutor randomExecutor


}

I want to use RandomExecutor mock bean in ServiceIntegTest class, how to do it ?

I am not mocking methods of the bean in TestConfig class itself, because in ServiceIntegTest class there are various tests in which methods of RandomExecutor have to behave in different ways.

Answer 1

You do not have to @MockBean in your config, you have to do it in the test class. Then you can mock it in some test classes and use a real instance in others.

Have a look at a basic usage of @MockBean : https://www.infoworld.com/article/3543268/junit-5-tutorial-part-2-unit-testing-spring-mvc-with-junit-5.html

Answer 2

You use a MockBean as you would a @Mock It just get injected into a spring context you're using for your test.

@SpringBootTest
class ServiceIntegTest {
  @MockBean RandomExecutor randomExecutor;

  // this service gets autowired from your actual implementation,
  // but injected with the mock bean you declared above
  @Autowired
  YourService underTest;

  @Test
  void verifyValueUsed() {
    final int mockedValue = 5;
    when(randomExecutor.getThreadCount()).thenReturn(mockedValue);
    int result = underTest.getExecutorThreads();

    assertThat(result).isEqualTo(mockedValue);
  }

  @Test
  void verifyExecutorCalled() {
    underTest.performAction("argument");
    verify(randomExecutor).executorMethod("argument");
  }
}