Spring Boot Unit Test a module not detecting an autowired component

Question

we have split our Maven based Spring Boot project into two modules as follows:

ProjectRoot
-SharedModel
-Application
--main
---java
----com....(Application.java)
-----com....(ClassToAutowire.java)
--test
----com....(ApplicationTest.java)
-----com....(ClassToAutowireTest.java)

The test class looks as follows:

@RunWith(SpringRunner.class)
public class ClassToAutowireTest extends BaseTest {

    @Autowired
    private ClassToAutowire classToAutowire;

    @Before
    public void setup() throws IOException {        
    ....
    }

    @Test
    public void someTest() {
        ....
        assertEquals(this.classToAutowire.isSupported(this.message), true);
    }

}

The ClassToAutowire looks like the follows:

@Component
public class ClassToAutowire {

    private ConfigurationService configurationService;

    @Autowired
    public ClassToAutowire(ConfigurationService configurationService) {
        this.configurationService = configurationService;
    }



    ....

}

The Application.java looks as follows:

@SpringBootApplication
@EnableRetry
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

And the ApplicationTest.java looks as follows:

@SpringBootTest
@RunWith(SpringRunner.class)
public class ApplicationTests {

    @Test
    @Ignore
    public void contextLoads() {
        // °º¤ø,¸¸,ø¤º°`°º¤ø,¸,ø¤°º¤ø,¸¸,ø¤º°`°º¤ø,¸
    }
}

When I run this Unit Test, we get the following trace:

    2018-06-27 15:02:37.835 ERROR [                                main] context.TestContextManager.prepareTestInstance(TestContextManager.java:234): Caught exception while allowing TestExecutionListener [org.springframework.test.context.support.DependencyInjectionTestExecutionListener@57c03d88] to prepare test instance [com.some.package.structure.ClassToAutowireTest@16aa8654]
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'com.some.package.structure.ClassToAutowireTest': Unsatisfied dependency expressed through field 'classToAutowire'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.some.package.structure.ClassToAutowire' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireBeanProperties(AbstractAutowireCapableBeanFactory.java:386)
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:118)
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:83)
    at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:230)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:228)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:287)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:289)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:247)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.some.package.structure.ClassToAutowire' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1493)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1104)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585)
    ... 27 more

Looks like this problem can be bypassed by adding the annotation @SpringBootTest(classes={ClassToAutowire.class}) below the @RuneWith annotation, but then the unit test seems to load the whole SpringBoot app to run test.

My questions are:

1) Why is this extra annotation needed to workaround the problem? It is supposed to scan the entire Application/main/java/.... (based on Application.java), so why is it not detecting the component?

2) How best to do it, with minimal loading to make unit tests faster?

Answer 1

Provide your test with @ContextConfiguration(classes = ClassToAutowire.class), then your context will be provided with that class. @SpringBootTest annotation is used in Integration Tests to load full context. With @ContextConfiguration annotation you are able to load only part of context.