Jib is a powerful container image builder for Java applications that simplifies the process of packaging and deploying Java applications as Docker containers. It offers seamless integration with various Java testing frameworks and libraries, enabling developers to test their containerized applications effectively. In this blog post, we will explore how Jib integrates with some popular Java testing frameworks and libraries.

JUnit

JUnit is a widely used testing framework for Java applications. Jib provides convenient integration with JUnit, allowing developers to run JUnit tests against the container image. By leveraging Jib’s integration with JUnit, developers can ensure that their containerized application functions correctly in the target environment.

To integrate JUnit with Jib, follow these steps:

1. Add the JUnit dependency to your project’s build file, such as Maven or Gradle.

   // Maven
   <dependency>
       <groupId>org.junit.jupiter</groupId>
       <artifactId>junit-jupiter-engine</artifactId>
       <version>5.8.1</version>
       <scope>test</scope>
   </dependency>
   
   // Gradle
   testImplementation 'org.junit.jupiter:junit-jupiter-engine:5.8.1'
   

2. Write your JUnit tests as per the standard JUnit guidelines.

   import org.junit.jupiter.api.Assertions;
   import org.junit.jupiter.api.Test;
   
   public class MyTests {
       @Test
       public void testSomething() {
           Assertions.assertEquals(2, 1 + 1);
       }
   }
   

3. Configure Jib to include the test classes by adding the following configuration to your project’s Jib configuration file (jib-maven-plugin for Maven or jib task for Gradle).

   // Maven
   <build>
       <plugins>
           <plugin>
               <groupId>com.google.cloud.tools</groupId>
               <artifactId>jib-maven-plugin</artifactId>
               <version>3.3.0</version>
               <configuration>
                   <extraDirectories>
                       <paths>
                           <path>
                               <from>target/test-classes</from>
                               <into>/app/test-classes</into>
                           </path>
                       </paths>
                   </extraDirectories>
               </configuration>
           </plugin>
       </plugins>
   </build>
   
   // Gradle
   jib {
       extraDirectories = [
           paths: [
               [from: "$projectDir/build/classes/java/test", into: '/app/test-classes']
           ]
       ]
   }
   

4. Build and push your container image as usual using Jib.

   mvn compile jib:build
   # or
   gradlew jib
   

With Jib’s integration with JUnit, you can easily incorporate comprehensive testing into your containerized Java applications workflow.

Mockito

Mockito is a popular mocking framework for Java applications, widely used for writing unit tests. Jib provides seamless integration with Mockito, allowing developers to incorporate mock-based testing in their containerized Java applications.

To integrate Mockito with Jib, follow these steps:

1. Add the Mockito dependency to your project’s build file, such as Maven or Gradle.

   // Maven
   <dependency>
       <groupId>org.mockito</groupId>
       <artifactId>mockito-core</artifactId>
       <version>4.2.0</version>
       <scope>test</scope>
   </dependency>
   
   // Gradle
   testImplementation 'org.mockito:mockito-core:4.2.0'
   

2. Write your Mockito-based tests following the standard Mockito guidelines.

   import org.junit.jupiter.api.Assertions;
   import org.junit.jupiter.api.Test;
   import org.mockito.Mockito;
   
   public class MyMockTests {
       @Test
       public void testSomething() {
           MyService myServiceMock = Mockito.mock(MyService.class);
           Mockito.when(myServiceMock.getValue()).thenReturn(10);
   
           int value = myServiceMock.getValue();
           Assertions.assertEquals(10, value);
       }
   }
   

3. Configure Jib to include the test classes by adding the following configuration to your project’s Jib configuration file (similar to the JUnit integration example).

4. Build and push your container image using Jib.

With Jib’s integration with Mockito, you can easily perform mock-based testing on your containerized Java applications.

#Conclusion

Jib’s integration with popular Java testing frameworks and libraries like JUnit and Mockito simplifies the testing process for containerized Java applications. By leveraging these integrations, developers can ensure the correctness and reliability of their applications within container environments. So give it a try and streamline your Java testing workflow with Jib!

#techblog #JavaTesting