How to use @ComponentScan together with test-specific ContextConfigurations in SpringJunit4TestRunner?

Question

I am testing a Spring Boot application. I have several test classes, each of which needs a different set of mocked or otherwise customized beans.

Here is a sketch of the setup:

src/main/java:

package com.example.myapp;  @SpringBootApplication @ComponentScan(         basePackageClasses = {                 MyApplication.class,                 ImportantConfigurationFromSomeLibrary.class,                 ImportantConfigurationFromAnotherLibrary.class}) @EnableFeignClients @EnableHystrix public class MyApplication {     public static void main(String[] args) {         SpringApplication.run(MyApplication.class, args);     } }  package com.example.myapp.feature1;  @Component public class Component1 {     @Autowired     ServiceClient serviceClient;      @Autowired     SpringDataJpaRepository dbRepository;      @Autowired     ThingFromSomeLibrary importantThingIDontWantToExplicitlyConstructInTests;      // methods I want to test... } 

src/test/java:

package com.example.myapp;  @RunWith(SpringJUnit4ClassRunner.class) @SpringApplicationConfiguration(classes = MyApplication.class) @WebAppConfiguration @ActiveProfiles("test") public class Component1TestWithFakeCommunication {      @Autowired     Component1 component1; // <-- the thing we're testing. wants the above mock implementations of beans wired into it.      @Autowired     ServiceClient mockedServiceClient;      @Configuration     static class ContextConfiguration {         @Bean         @Primary         public ServiceClient mockedServiceClient() {             return mock(ServiceClient.class);         }     }      @Before     public void setup() {         reset(mockedServiceClient);     }      @Test     public void shouldBehaveACertainWay() {         // customize mock, call component methods, assert results...     } }  package com.example.myapp;  @RunWith(SpringJUnit4ClassRunner.class) @SpringApplicationConfiguration(classes = MyApplication.class) @WebAppConfiguration @ActiveProfiles("test") public class Component1TestWithRealCommunication {      @Autowired     Component1 component1; // <-- the thing we're testing. wants the real implementations in this test.      @Autowired     ServiceClient mockedServiceClient;      @Before     public void setup() {         reset(mockedServiceClient);     }      @Test     public void shouldBehaveACertainWay() {         // call component methods, assert results...     } } 

The problem with the above setup is that the component scan configured in MyApplication picks up Component1TestWithFakeCommunication.ContextConfiguration, so I get a mock ServiceClient even in Component1TestWithRealCommunication where I want the real ServiceClient implementation.

Although I could use @Autowired constructors and build up the components myself in both tests, there is a sufficient amount of stuff with complicated setup that I would rather have Spring TestContext set up for me (for example, Spring Data JPA repositories, components from libraries outside the app that pull beans from the Spring context, etc.). Nesting a Spring configuration inside the test that can locally override certain bean definitions within the Spring context feels like it should be a clean way to do this; the only downfall is that these nested configurations end up affecting all Spring TestContext tests that base their configuration on MyApplication (which component scans the app package).

How do I modify my setup so I still get a "mostly real" Spring context for my tests with just a few locally overridden beans in each test class?

Answer 1

The following should help you to achieve your goal by introducing a new fake-communication profile that is applicable only to the current test class.

@RunWith(SpringJUnit4ClassRunner.class) @SpringApplicationConfiguration(classes = MyApplication.class) @WebAppConfiguration @ActiveProfiles({"test", "fake-communication"}) public class Component1TestWithFakeCommunication {      // @Autowired ...      @Profile("fake-communication")     @Configuration     static class ContextConfiguration {         @Bean         @Primary         public ServiceClient mockedServiceClient() {             return mock(ServiceClient.class);         }     } }