How to overwrite nested dependencies for an integration test.

001_BusinessService.java

package demo.business;

public interface BusinessService {
	void businessMethod();
}

010_DefaultBusinessService.java

package demo.business;

import org.springframework.beans.factory.annotation.Autowired;

public class DefaultBusinessService implements BusinessService {

	private final Dependency dependency;

	@Autowired
	public DefaultBusinessService(Dependency dependency) {
		this.dependency = dependency;
	}

	@Override
	public void businessMethod() {
		System.out.println(dependency);
	}
}

020_Dependency.java

package demo.business;

public interface Dependency {}

030_DefaultDependency.java

package demo.business;

public class DefaultDependency implements Dependency{}

040_BusinessConfig.java

package demo.business;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class BusinessConfig {
	
	@Bean
	public BusinessService businessService(Dependency dependency) {
		return new DefaultBusinessService(dependency);
	}
	
	@Bean
	public Dependency dependency() {
		return new DefaultDependency();
	}
}

050_BusinessServiceIT.java

package demo.business;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@ContextConfiguration
@RunWith(SpringJUnit4ClassRunner.class)
public class BusinessServiceIT {
	
	@Autowired BusinessService businessService;
	
	@Import(BusinessConfig.class)
	@Configuration
	static class Config{
		//@Bean @Primary //uncomment the bean definition to get the "mock" dependency wired into the DefaultBusinessService
		public Dependency dependency(){
			return new Dependency() {};
		}
	}

	@Test
	public void test() {
		businessService.businessMethod();
	}
}