Injecting Mockito mocks into a Spring bean
### Injecting Mockito Mocks into a Spring Bean
Mockito is a popular mocking framework for Java. It allows you to create mock objects that can be used to test your code. However, when you are using Mockito with Spring, there are some additional steps that you need to take to inject the mock objects into your Spring beans.
There are multiple ways to inject Mockito mocks into a Spring bean:
- **Using `@MockBean` annotation:** This is the most straightforward approach and is recommended for Spring Boot applications.
- **Using a `FactoryBean`:** This approach involves creating a factory bean that returns mocks.
- **Using a custom `ApplicationContextInitializer`:** This approach allows you to customize the Spring application context and inject mocks into your beans.
Here's an example of how to inject a Mockito mock into a Spring bean using the `@MockBean` annotation:
```java
@RunWith(SpringRunner.class)
@SpringBootTest
public class MyServiceTest {
@MockBean
private MyDependency dependency;
@Autowired
private MyService service;
@Test
public void test() {
// Use the mock to test the service
when(dependency.doSomething()).thenReturn("mocked");
String result = service.doSomething();
assertEquals("mocked", result);
}
}
```
In this example, the `@MockBean` annotation is used to create a mock of the `MyDependency` class. The mock is then injected into the `MyService` class using the `@Autowired` annotation.
Here's an example of how to inject a Mockito mock into a Spring bean using a `FactoryBean`:
```java
public class MyFactoryBean implements FactoryBean<MyDependency> {
@Override
public MyDependency getObject() throws Exception {
return mock(MyDependency.class);
}
@Override
public Class<MyDependency> getObjectType() {
return MyDependency.class;
}
@Override
public boolean isSingleton() {
return true;
}
}
@Configuration
public class MyConfig {
@Bean
public MyFactoryBean myFactoryBean() {
return new MyFactoryBean();
}
}
```
In this example, the `MyFactoryBean` class is used to create a factory bean that returns mocks. The factory bean is then registered as a bean in the Spring application context using the `@Bean` annotation.
Here's an example of how to inject a Mockito mock into a Spring bean using a custom `ApplicationContextInitializer`:
```java
public class MyApplicationContextInitializer implements ApplicationContextInitializer<GenericApplicationContext> {
@Override
public void initialize(GenericApplicationContext applicationContext) {
// Create a mock of the MyDependency class
MyDependency mock = mock(MyDependency.class);
// Register the mock as a bean in the application context
applicationContext.registerBean("myDependency", MyDependency.class, mock);
}
}
@Configuration
public class MyConfig {
@Bean
public static MyApplicationContextInitializer myApplicationContextInitializer() {
return new MyApplicationContextInitializer();
}
}
```
In this example, the `MyApplicationContextInitializer` class is used to create a custom `ApplicationContextInitializer`. The `ApplicationContextInitializer` is then registered as a bean in the Spring application context using the `@Bean` annotation.