SpringBootTest - how to replace one bean in runtime configuration?

Unit Test with One Bean

Just use @RunWith(SpringRunner.class) annotation, it should work. You can also use @RunWith(SpringJUnit4ClassRunner.class). Both should work.

Please don't use @SpringBootTest annotation. It will wire up the whole application.

Here is your updated example,

@RunWith(SpringRunner.class)
public class CombinedControllerIntegrationTest2 {

    @TestConfiguration
    static class ContextConfiguration {

        @Bean
        public SolrDocumentTypeMapRepository solrDocumentTypeMapRepository() {
            LOG.debug("SolrDocumentTypeMapRepository is being initialized.");
            return new SolrDocumentTypeMapRepository(...);
        }
    }

    @Autowired
    private SolrDocumentTypeMapRepository repository;

    @Test
    public void test() {
        assertNotNull(repository);
    }
}

Integration Test with a Replaced Bean

• Create a new test Spring Boot application. It should exclude the configuration class (for e.g., SolrConfiguration) which is responsible for creating SolrDocumentTypeMapRepository bean.

  @SpringBootApplication
  @ComponentScan(basePackages = {
          "com.abc.pkg1",
          "com.abc.pk2"},
          excludeFilters = {
                  @ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE, 
                  value = SolrConfiguration.class)})
  public class TestApplication {
      public static void main(String[] args) throws Exception {
          SpringApplication.run(TestApplication.class, args);
      }
  }
  

• Now, use the @ContextConfiguration annotation in your test class to add the TestApplication.class and the ContextConfiguration.class. This will wire up your application with the all the required beans including the replaced bean. Shown below is the updated test class,

  @ActiveProfiles("test")
  @RunWith(SpringJUnit4ClassRunner.class)
  @SpringBootTest(webEnvironment = 
      SpringBootTest.WebEnvironment.RANDOM_PORT)
  @ContextConfiguration(classes = {TestApplication.class, 
      CombinedControllerIntegrationTest2.ContextConfiguration.class})
  public class CombinedControllerIntegrationTest2 {
  
      @TestConfiguration
      static class ContextConfiguration {
  
          @Bean
          public SolrDocumentTypeMapRepository solrDocumentTypeMapRepository() {
              LOG.debug("SolrDocumentTypeMapRepository is being initialized.");
              return new SolrDocumentTypeMapRepository(...);
          }
      }
  
      ...
  }