Introduction

With the rapid advancement in Java technology, the application development and deployment process has been refined to a great extent. From the waterfall model to Agile and now transitioning towards the DevOps, many enhancements have been made in the process to improve the quality of java applications.

With production getting better, testing processes were also needed to be improved to avoid any bottleneck in the production process. Traditional testing methods like integration testing and unit testing have been improved to get more accurate and faster results. Java developers can now run integration tests automatically during build time using continuous integration frameworks like Jenkins or TeamCity.

In this article, we will be focusing primarily on Java Integration testing and how it can be implemented in the Java applications building process.

Integration Testing 

Integration testing involves testing the working of individual units altogether to check whether all the units are interacting with each other as expected, as the complexity of applications has increased so much that a single method is likely to be interacting with more than one method from multiple classes.

Such complexity is still a bit manageable with unit testing of an individual unit, but when it comes to integration testing, the involvement of multiple units significantly increases the complexity as well as the frequency of test cases to be checked to ensure the working of all the units. To cater to that, Java developers use continuous Integration with java integration testing.

How Integration Testing Is Implemented With CI (Continuous Integration)

With the introduction of continuous integration testing environments, integration testing has evolved a lot, but it is still difficult for many java developers (especially beginners) to understand how does Java integration testing fit into the continuous integration (CI) environment and how is it feasible to test and modify the code during development?

Along with the above questions, many other queries and misconceptions can also be resolved by applying some simple yet best practices in your java integration testing process. 

Previously, integration testing used to be implemented after unit testing and just before validation testing. This order was perfect for the waterfall model. When the agile models were introduced, the previously well-divided phases were now sort of merging, as every time a developer commits a code, it initiates the whole production cycle. As a result, tasks from every development phase happen all at once.

Now the question of where integration testing is supposed to fit in this type of models can be answered through a tailor-made testing strategy. You will be required to generate a custom strategy by following some famous practices to seamlessly implement the integration testing with proper results.

Best Practices For Java Integration Testing

Following are some of the best practices you should apply while implementing Java integration testing:

1. Never Test Business Logic With Integration Testing

Business logic is the main rules or algorithms behind your application that needs to be tested separately. You must never attempt to apply integration testing on any unit that should be first tested by unit testing. It can result in dire consequences as access resources will be used with less accurate results. Unit testing is relatively faster, so it is done for every build triggered in the CI environment. It is critical to find and remove any defects that are present in the early stages of the development of business logic.

On the contrary, Integration tests take relatively more time to run, so it would be ideal for running it at the end of the daily build to check the Integration of business logic, not the business logic itself.

2. Understand Why Integration Testing Is Different From Unit Testing

Many simple signs can be used to easily differentiate a unit test from an integration test. This differentiation is important because it also helps in identifying the cause of test failure.

Unit tests are always well encapsulated and do not require external resources, whereas integration tests always need additional components or infrastructures like the network or the database to check the coordination between different units.

Unit tests are usually small and independent of code which makes them less complex to write. Integration tests, on the other hand, are more complex, usually requiring different tooling and different infrastructures for testing.

A unit test failure indicates a bug in the business logic of the application, but the failure of integration tests means that something has been changed in the environment and needs to be corrected. It has no concern with the business logic.

3. Always Keep The Testing Suites Separate

Integration tests should never run along with unit tests. You cannot start with Java integration testing before testing individual units, but it is also not feasible to start Integration testing of those units that have passed unit testing along with other unit tests. Java developers working on the code must be able to run unit tests and get immediate feedback (as unit testing takes less time) to ensure that the unit is working as expected before committing the code.

In case while performing both testings together, if their test suite takes too long (as Integration testing takes longer) and you cannot afford to wait for it to finish before committing the code, you will have to stop all the tests (both unit tests and integration tests) from committing the code. This will result in unit tests not being able to be properly maintained as well as it will causes delays due to reattempting of testing.

By keeping the test suites separate, it will be convenient for developers to quickly run the unit tests during development before committing any code. The lengthy and time taking integration tests can be reserved for a separate test suite, so they will be needed to run less frequently.

4. Extensive Logging Should Be Done For Integration Testing

Unit testing has a specific scope, and the tests are usually very small as they are limited to a single unit. So, if a test is unsuccessful, you can easily detect the problem and fix the problem. Integration tests are not that simple. Its scope may include units from different parts of the application, and it can also include different devices and hardware components as some units in an application also work with hardware. In case an integration test fails, it will be way more complex to pinpoint its cause.

Detailed logging will be required to find the cause of failure. Although the logging process can have a significant effect on performance, it should be applied when the chances of failures are significant, or the integration testing process is very complex.

5. Integration Testing Must Be Implemented After Deployment As Well

Java integration testing must not be concluded after testing whether your java application modules work fine with one another or with the hardware components. It must be implemented beyond this.

A complete java application will be most likely deployed in a complete production ecosystem that may have a database, mail servers and more systems. The user’s experience will be depending not only on the application but also on how it is deployed and how it works with all the other components. Make sure to run system tests after deployment to test whether the application is working as required in the production environment.

6. Never Underestimate Integration Testing; It Is Always Worthwhile

Despite being more time consuming, complicated and relatively expensive, Java integration testing has always been worthwhile as it will be much more expensive to fix defects in your code if they are discovered much later in the production phase.

Best Java Integration Testing tools and frameworks

After applying the above-mentioned practices, now you will just be needing a testing framework to implement the java integration testing efficiently.

A java integration test framework can make things significantly easier and controllable for test engineers and quality assurance staff to perform regression testing.

Following are some of the best java integration test frameworks that can help Java developers in writing integration tests on their various Java projects and implementing a successful integration testing process.

1. Junit

JUnit is the most popular regression testing framework used by java developers for different types of testing. It is primarily used for unit testing, but due to its active users and popularity, many Java developers also use it for Integration testing. It also offers integration testing features as it supports Java 8 features.

Defects can be easily identified and resolved in the early phase, ensuring a stable and error-free code. You can conduct automated tests of a Java web app by combining Selenium WebDriver with JUnit for Java automated testing.

2. Citrus

Citrus is a java integration test framework primarily used for automated integration testing of message-based application and data formats. Citrus validates for multiple scripting languages, including JSON, XML and plain text messaging request and response data. It is an open-source tool for java integration testing.

3. Spock for JAVA

Spock is a testing framework for Java and Groovy applications. It is fully compatible with a range of different java IDEs and continuous integration servers. Spock offers very easily writable and readable tests. It also has unique features like performing both assertion checking and mocking at the same time.

4. TestNG

TestNG is amongst the most popular and powerful Java testing frameworks used for Integration testing. It gives tough competition to some prominent frameworks like the JUnit framework because TestNG offers some superior functionalities that are not supported by Junit.

5. HTMLUnit

It an open-source library and a headless browser used for integration testing. HTMLUnit emulates browser like behaviour, and that is why it is extensively used for Integration testing. JSPs (Java Server Pages) are designed to run inside the web container and are converted into Servlet when the Web Server runs. HTMLUnit’s highlighting feature is that it can also be used to test the View part even without the container.

6. JwebUnit

JWebUnit is another Java integration test framework. It is one of the JUnit extensions that wraps the current active frameworks like HTMLUnit and Selenium with a simple test interface, allowing you to instantly test the accuracy of your Java web apps.

7. DBUnit

DBUnit is another extension of the JUnit framework. It is primarily used to test database-driven projects that integrate the database with other components. It holds the database into a known state between test runs. It is an intelligent move as a lot of problems can be avoided in case any test case does not work well and ends up corrupting the database. However, the database can always be restored from known states in such a case. 

It offers a unique feature to import and export the database to and from XML datasheets. In streaming mode, it can also efficiently work with large data sets and also helps in verifying the database data match as an expected set of data values.

 8. Arquillian

 Arquillian is a very powerful and mature tool use for Integration and Functional testing of Java applications. It is usually used with the Maven build tool along with a Testing framework like JUnit or TestNG. Its praising feature is that it frees the testers from creating Mock objects. Arquillian offers testing for JSF, EJB, Servlets and some other Java classes as well.

Conclusion:

With rapid advancements in the field of tech, new features are introduced every day. And with developers working on the same project from around the world sitting at different locations, Java integration testing has become a must. Integration testing has become equally essential whether you are a small or mid-tier company or working at a tech giant.

See Also: Top Java Build Tools And Continuous Integration Tools You Should Start Using In 2021.

We have discussed some best practices you can apply to implement integration testing. Some prominent frameworks have also been discussed to give you a head start if you wish to start implementing integration testing in your java build processes.

Author

Shaharyar Lalani is a developer with a strong interest in business analysis, project management, and UX design. He writes and teaches extensively on themes current in the world of web and app development, especially in Java technology.

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