Why component scanning does not work for Spring Boot unit tests?

Question

The service class FooServiceImpl is annotated with @Service aka @Component which makes it eligible for autowiring. Why this class is not being pick

Answer 1

A unit test should test a component in isolation. You don`t even need to use the Spring Test context framework for a unit test. You can using mocking frameworks such as Mockito, JMock or EasyMock to isolate the dependencies in your component and verify the expectations.

If you want a true integration test then you need to use the @SpringBootTest annotation on your test class. If you dont specify the classes attribute it loads the @SpringBootApplication annotated class. This results in production components like db connections being loaded.

To eliminate these define a separate test configuration class which for example defines an embedded database instead of the production one

@SpringBootTest(classes = TestConfiguration.class)
public class ServiceFooTest{
}

@Configuration
@Import(SomeProductionConfiguration.class)
public class TestConfiguration{
   //test specific components
}