Use different Spring test context configuration for different test methods

Question

We have a Spring based JUnit test class which is utilizing an inner test context configuration class

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = ServiceTest.Config.class)
public class ServiceTest {

    @Test
    public void someTest() {
    ...

    @Configuration
    @PropertySource(value = { "classpath:application.properties" })
    @ComponentScan({ "..." })
    public static class Config {
    ...

New functionalities have been recently introduced to the Service class, for which the concerned tests should be added to ServiceTest. However these would also require a different test context configuration class to be created (the internals of the existing Config class are fairly complex and change it to serve both old and new tests seems to be be extremely difficult if possible at all)

Is there a way to achieve that certain test methods in one test class would use one config class and other methods would use another? @ContextConfiguration seems to be applicable only on class level, so solution could be to create another test class for the new tests which would utilize its own context configuration class; but it would mean that the same Service class is being covered via two different test classes

Answer 1

With Aaron's suggestion of manually building the context I couldn't find any good examples so after spending some time getting it working I thought I'd post a simple version of the code I used in case it helps anyone else:

class MyTest {

    @Autowired
    private SomeService service;
    @Autowired
    private ConfigurableApplicationContext applicationContext;

    public void init(Class<?> testClass) throws Exception {
        TestContextManager testContextManager = new TestContextManager(testClass);
        testContextManager.prepareTestInstance(this);
    }

    @After
    public void tearDown() throws Exception {
        applicationContext.close();
    }

    @Test
    public void test1() throws Exception {
        init(ConfigATest.class);
        service.doSomething();
        // assert something
    }

    @Test
    public void test2() throws Exception {
        init(ConfigBTest.class);
        service.doSomething();
        // assert something
    }

    @ContextConfiguration(classes = {
        ConfigATest.ConfigA.class
    })
    static class ConfigATest {
        static class ConfigA {
            @Bean
            public SomeService someService() {
                return new SomeService(new A());
            }
        }
    }

    @ContextConfiguration(classes = {
        ConfigBTest.ConfigB.class
    })
    static class ConfigBTest {
        static class ConfigB {
            @Bean
            public SomeService someService() {
                return new SomeService(new B());
            }
        }

    }
}