Overriding an Autowired Bean in Unit Tests

Question

Is there a simple way I can easily override an autowired bean in specific unit tests? There is only a single bean of every type in the compile classes so it\'s not a problem

Answer 1

If you just simply want to provide a different bean in your tests, i think you don't need to use spring profiles or mockito.

Just do the following:

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = { TestConfig.class })
public class MyTest
{
    @Configuration
    @Import(Application.class) // the actual configuration
    public static class TestConfig
    {
        @Bean
        public IMyService myService()
        {
            return new MockedMyService();
        }
    }

    @Test
    public void test()
    {
        ....
    }
}

NOTE: tested with spring boot 1.3.2 / spring 4.2.4

Answer 2

As mats.nowak commented, @ContextConfiguration is useful for this.

Say a parent test class is like:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:spring/some-dao-stuff.xml"
    ,"classpath:spring/some-rest-stuff.xml"
    ,"classpath:spring/some-common-stuff.xml"
    ,"classpath:spring/some-aop-stuff.xml"
    ,"classpath:spring/some-logging-stuff.xml"
    ,"classpath:spring/some-services-etc.xml"
})
public class MyCompaniesBigTestSpringConfig {
...

Create a child test class:

package x.y.z;
@ContextConfiguration
public class MyOneOffTest extends MyCompaniesBigTestSpringConfig {
...

and put in src/test/resources/x/y/z/MyOneOffTest-context.xml

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                           http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
                           http://www.springframework.org/schema/context
                           http://www.springframework.org/schema/context/spring-context-3.0.xsd">


    <bean id="widgetsService" class="com.mycompany.mydept.myservice.WidgetsService" primary="true" />

</beans>

That widgetsService bean will override (take the place of) the bean defined in the main config xml (or Java config). See about inheritLocations Also Note the default -context.xml file. Example of that here. Update: I had to add primary="true", apparently it's needed.

Answer 3

You should use spring profiles in order to know what kind of bean you want to use in different contexts.

http://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-profiles.html

Answer 4

I had similar problem and I solved with a mix and I find this one more useful and reusable. I created a spring profile for the tests and a config class that overrides the beans I want to mock in a very simple way:

@Profile("test")
@Configuration
@Import(ApplicationConfiguration.class)
public class ConfigurationTests {

    @MockBean
    private Producer kafkaProducer;

    @MockBean
    private SlackNotifier slackNotifier;

}

By doing that I can @Autowire those mock beans and use mockito to verify on them. Main advantage is that now all tests seamlessly get the mock beans without any per-test change. Tested with:

spring boot 1.4.2

Answer 5

In Spring Boot 1.4 there's a simple way for doing that:

@RunWith(SpringRunner.class)
@SpringBootTest(classes = { MyApplication.class })
public class MyTests {
    @MockBean
    private MyBeanClass myTestBean;

    @Before
    public void setup() {
         ...
         when(myTestBean.doSomething()).thenReturn(someResult);
    }

    @Test
    public void test() {
         // MyBeanClass bean is replaced with myTestBean in the ApplicationContext here
    }
}