Testing Spring Boot Library Modules

Question

I got a multi module project where not every module is actually an application but a lot of them are libs. Those libs are doing the major work and I want to test them where they are implemented. The current dependencies of the libs:

implementation 'org.springframework.boot:spring-boot-starter'
testImplementation 'org.springframework.boot:spring-boot-starter-test'

In the main source is a class with @Configuration and a single bean:

@Bean public String testString() { return "A Test String"; }

I got 2 test classes:

@RunWith(SpringRunner.class)
@SpringBootTest
@ActiveProfiles({"default", "test"}) 
public class Test1 {  

    @Test
    public void conextLoaded() {
    }
}

-

@RunWith(SpringRunner.class)
@SpringBootTest
@ActiveProfiles({"default", "test"}) 
public class Test2 {  
    @Autowired
    private String testString; 

    @Test
    public void conextLoaded() {
    }
}

The first test works. The second does not. There is not @SpringBootApplication anywhere in that project so in the same package as the Tests I added a test configuration:

@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan("com.to.config") 
public class LibTestConfiguration {
}

And it does not work. Same for classes that are @Service. They are not in the context. How can I make it behave like a normal Spring boot application without it actually beeing one and load the configs and contexts from the configurations files I need? The default and test profile share most of their properties (for now) and I want them to be loaded like I would start a tomcat.

Answer 1

I switched to JUnit 5 and made it kinda work... So if you want to test Database stuff:

@DataMongoTest
@ExtendWith(SpringExtension.class)
@ActiveProfiles({"default", "test"})
class BasicMongoTest { ... }

• Lets you autowire all repositories and mongo template
• Initializes with apllicaton.yml config
• Does NOT initialize or configure interceptors

---

Full application context test if you have a class with @SpringBootApplication in your classpath (Can be an empty test main in your test context)

@SpringBootTest
@ExtendWith(SpringExtension.class)
@ActiveProfiles({"default", "test"})
public class FullContextTest { ... }

• Initializes the full context with all configs and beans
• Should not be done if not necessary as it loads all the application context and kinda defeats the purpose of unit tests to only activate whats needed.

---

Test only specific components and configs:

@SpringBootTest(classes = {Config1.class, Component1.class})
@EnableConfigurationProperties
@ExtendWith(SpringExtension.class)
@ActiveProfiles({"default", "test"})
public class SpecificComponentsTest { ... }

• Initializes the context with only the Config1 and Component1 classes. Component1 and all beans in Config1 can be autowired.