Integration Testing with Java: Best Practices and Frameworks to Use in 2023

At this point, you might ask, “Why is the CEO writing an article about testing?” The answer is simple—I began as a software engineer and IT consultant, having developed and supported software applications for business process automation. As our team has been working together for years, we have a strong bond that enhances our communication, so everyone from the CEO to the CTO to a developer is on the same page.

 In a company like ours, it’s essential not to micromanage but get involved personally and pay attention to every project and every client. To me, that matters.

What is integration testing, and why you need it

In unit testing, you check the code bit by bit, each set of modules separately. In integration testing, a type of functional testing, you check if these units integrate and perform together just as you need them. It’s like hiring a team one by one and, during each trial period making sure that, for instance, this Java developer has sufficient hard skills, gets along with the others, and shares the team spirit. 

Besides, your Java developer will need to fit in the larger corporate context and beyond: communicate cross-team and, possibly, with clients or other parties. You also need to test that combination for your software and third-party apps or plugins. 

The benefits integration testing secures for your software include the following:

• • Overall software reliability and robustness
  • Successful execution of user-based scenarios
  • Effective communication between internal modules and components
  • Additional regression testing on key connection points
  • Opportunity for unplanned, or ad-hoc tests, which will help eliminate the hidden defects

• Best practices to elevate Java integration testing

• I will leave the intricacies to our QAs and provide simple and general recommendations to help your team tweak the integration routine.

  1. Each developer should document dependencies if they use a staging environment. Other developers should know about these dependencies to avoid test failures due to a lack of network access to the testing infrastructure.
     
  2. Never mix your integration tests with unit tests. Unless you want some of the tests to slow down or halt in a snowballing progression, which will be impossible to solve for all the tests at once. If you don’t want a test suite mess that will weigh your project down, separate the suites for the two test types.
  3. Run integration tests before unit tests. Changes in business logic, which might result from unit testing, became easy to address in the agile environment—developers no longer need to comb out all the bugs before tackling the bigger picture of integration.
  4. Leave the code alone when the integration test fails. Most probably, some change in the environment triggered the failure. For handling the bugs, there are unit tests.
     
  5. Test the public API of the classes. This way, you’ll prevent new bugs from popping up in your system and protect the functionality.

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Top 5 frameworks for Java testing

TestNG

TestNG is one of the most popular frameworks for testing how your software modules blend. Open-source and automated, TestNG outdoes the older tools with more flexibility and new features, including sequencing and parameterizing.

Pros:

• XML configuration for test suites
• Annotations for setup and cleanup
• Data-driven, dependent, and multithreaded testing
• Flexible API plugin 

Cons:

• Long setup of the framework
• Applicable only if you need to prioritize test cases

JUnit

Mainly used for unit testing, JUnit can handle integration testing on a top level, too. However, it’s not fit for UI-type testing. 

Pros:

• Efficient testing
• Annotations to save you time on test case writing
• Provides assertions for checking expected results
• Retesting of all possible scenarios

Cons:

• No group testing
• No dependency testing
• No GUI testing

Spring 

This framework is excellent for automating unit and integration tests of Spring-run apps. This one is our team’s favorite.

Pros:

• Test without web container launch
• Container-agnostic
• Annotation-driven
• Dependency Injection, transaction management, and other features
• Compatible with JUnit, TestNG, and other popular java testing frameworks 

Cons:

• Programming methods make it challenging to learn for inexperienced developers

Arquillian

This one is a Java integration testing framework specific to Java EE.

Arquillian helps spend less time and resources writing integration tests for Java Enterprise apps. 

Pros:

• Wraps everything for the test in the archive
• Manages containers and deploys archives to them
• Integrates with JUnit and TestNG
• Lets you regulate the size of the package for testing deployment 
• Has classpath control

Cons

• Separate deployment for each test execution
• Time-consuming test package creation

JWebUnit

One of JUnit's extensions, it’s a great automation tool you can utilize for regression and other functional testing.

Pros:

• Tailored to web apps testing
• Has a highly sophisticated yet intuitive test interface 
• Ensures effective screen navigation testing
• Tests app authenticity
• Provides assertions for checking expected results

Cons:

• JS for testing can be tricky and somewhat convoluted
• A headless server is not suitable for running a test with this tool
• Cost can bite, so you’ll need experts on your team to optimize the testing scope

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The final two cents on integration testing importance

Integration testing is a critical component in the software development lifecycle. 

• By adopting and executing this testing type ensures overall software reliability, successful execution of user-based scenarios, and effective communication between internal modules and components. 
• Implementing best practices and utilizing frameworks to optimize integration testing is essential. 
• Some of the most popular frameworks for Java testing include TestNG, JUnit, Spring, Arquillian, and JWebUnit. 

Following the best practices and leveraging the right tools for integration testing can help businesses achieve faster release cycles, increased reliability, and better customer satisfaction.

You can always find a skilled team of Java developers and testers here.