Spring Boot - Access Spring ApplicationContext in JUnit Tests

This post shows how to access the Spring ApplicationContext object in JUnit tests. Now, why would we want to do that? Well, sometimes, we need to work directly with the ApplicationContext object.

Spring, Java, and Other Requirements

We used the following items for this post. These are for reference only, but similar codes may still work using later versions of Java and Spring Boot.

Java 8 (JDK)
IntelliJ IDEA Ultimate 2016.3
Spring Boot 1.5.6.RELEASE

Spring @Component To Use in JUnit Tests

For this post, we use a Java class, and we annotate it with @Component. The idea is to let the Spring container load that bean and test if Spring instantiated the class in a JUnit test.

package com.turreta.springboot.applicationcontext.junit;

import org.springframework.stereotype.Component;

@Component
public class ImportantBean
{
    // Intentionally left empty
}

package com.turreta.springboot.applicationcontext.junit;

import org.springframework.stereotype.Component;

@Component

public class ImportantBean

{

// Intentionally left empty

}

JUnit Test And ApplicationContext

To test out the ImportantBean, we first try retrieving it from the Spring ApplicationContext. However, we need to use two class-level annotations and @Autowired.

@RunWith(SpringRunner.class)
@SpringBootTest

1 2	@RunWith(SpringRunner.class) @SpringBootTest

Here is the rest of the JUnit class that uses the Spring ApplicationContext.

package com.turreta.springboot.applicationcontext.junit;

...
import org.springframework.context.ApplicationContext;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest
public class ImportantBeanTest
{
    @Autowired
    private ApplicationContext context;

    @Test
    public void aComponent()
    {
        Assert.assertTrue(context.getBean(ImportantBean.class) != null);
     }
}