Overriding an Autowired Bean in Unit Tests - spring

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 for autowiring in this case. The test classes would contain additional mocks. When running a unit test I'd simply like to specify an additional Configuration that says basically, while running this unit test use this mock instead of the standard bean.
Profiles seem a bit overkill for what I require and I'm not sure this would be achievable with the Primary annotation as different unit test could have different mocks.

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

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
}
}

Answer 3

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 4

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 5

Since Spring Boot 1.4.0 instead of explicitly specifying #Configuration for tests, simply add static nested class annotated with #TestConfiguration and provide your replacement #Bean annotated with #Primary.
#TestConfiguration will be added to your primary Spring Boot test context (which means your production bean will still be created), but the one from #TestConfiguration will be used, because of the #Primary.

Answer 6

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.