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Friday, February 17, 2023

Top 10 Testing Tools and Libraries for Java Developers in 2024 [UPDATED]

In the last couple of weeks, I have written quite a few articles about what Java developers should learn in 2024 like programming languages, libraries, and frameworks, but if you have just one thing to improve or learn then that must be your testing skills. Testing is one of the disciplines which separates professional developers from amateur ones. It's not about following Test-driven development (TDD), Business Driven Development (BDD), or whatever testing methodologies but at the very minimum level, you must write code to test your code automatically. Many Java developers write unit tests and integration tests that automatically run during build time, mostly by using continuous integration tools like Jenkins or TeamCity.

If some of you thinking, why a programmer should focus on automation testing then let me tell you that the importance of automation testing is growing exponentially due to more awareness and the emergence of DevOps.

Companies generally prefer programmers who are good at writing unit tests and show good knowledge of various unit testing frameworks, libraries, and tools like JUnit, Selenium, REST-Assured, Spock framework, etc.

As a Java developer, we work in very different areas, starting from writing core Java code to creating JSP pages, writing REST APIs, and sometimes even creating Groovy scripts for build automation. That's why we also need to be aware of different tools we can use to automate testing of different Java stuff.

For example, I only knew JUnit for a long time but when I had to test my JSP pages, I was clueless until I found Selenium. The same goes for REST Assured because I usually test my REST API using the curl command, but REST Assured library takes the unit testing of REST APIs to another level.

10 Essential Unit and Integration Testing tools for Java Programmers

Since I believe, a programmer is as good as their tools, I always try to learn and explore new tools and libraries in my free time and this list is part of that research.

In this article, I am going to share 10 of the best and essential tools, frameworks, and libraries that can help Java developers writing unit tests and integration tests on their various Java projects.

1. JUnit

I don't think JUnit needs any introduction. Even if you are a beginner Java programmer, you might have heard about it. It allows you to write unit tests for your Java code.

Almost all major IDEs like Eclipse, NetBeans, and IntelliJ IDEA provide JUnit integration which means you can both write and run the unit test right from those IDE.

Most of us are still using JUnit 4 but JUnit 5 is already released and probably the next thing to look at this year. You can use JUnit for both unit and integration testing and it also supports Java 8 features.

Btw, if you are completely new in the unit testing world, particularly in Java unit testing then this Learn Java Unit Testing with Junit & Mockito in 30 Steps course on Udemy is a good starting point. You can buy in just $10 on Udemy sale. 

best courses to learn JUnit 5

2. Mockito

There are many mocking frameworks for Java classes like PowerMock, JMock but I personally like Mockito for its simple API, great documentation, and a lot of examples.

Mocking is one of the essential techniques of modern-day unit testing, as it allows you to test your code in isolation without any dependency and that's why I encourage every Java developer to learn a mocking framework along with JUnit.

My favorite mocking framework is Mockito but if you like you can also explore PowerMock or JMock.

If you choose to stick with Mockito and decide to learn this framework then this JUnit and Mockito Crash Course on Udemy is a good course to start with.

best mocking framework or library in Java

3. REST Assured

Testing and validating REST services in Java is harder than in dynamic languages such as Groovy. REST Assured brings the simplicity of using these languages into the Java domain. It's a great tool for REST API integration tests.

If you are serious about writing an integration test for your REST API, then you must learn the REST Assured and REST API Testing Automation: via REST Assured & HTTP Client course on Udemy is a good place to start with, I have already joined this course and will put some time aside to learn this tool in 2024.

unit testing tool for REST APIs Java

It covers many aspects of REST API testing like Automated REST API Testing using Rest Assured Java and RESTful web service Testing via POSTMAN and HTTP Client.

4. Selenium

Selenium is probably the most popular tool for Java UI testing, which allows you to test your JSP pages without launching them in a browser.

You can test your web application UI using JUnit and Selenium. It even allows you to write web application acceptance tests.

I am still new to Selenium and learning it on Selenium WebDriver with Java - Basics to the Advanced course on Udemy.

If you decide to learn Selenium for unit testing your code then you can join its tool, it is probably the best resource to start with.

You will learn complete knowledge of Selenium Webdriver with strong Core Java basics, particularly important for testers who want to learn Java for automation testing along with Selenium.

5. TestNG

TestNG is a testing framework inspired by JUnit and NUnit but introducing many new functionalities that make it more powerful and easier to use, such as annotations, Running your tests in arbitrarily big thread pools with various policies available (all methods in their own thread, one thread per test class, etc).

The gap between JUnit and TestNG has reduced because of using annotations from JUnit 4 and integrating the Hamcrest matchers as well but it's up to you.

If you decide to learn TestNG for unit testing your Java code then TestNG Complete Bootcamp For Beginners - Novice To Ninja is a good course to start with.

It provides step by step guide for learning TestNG Framework (Next Generation) to speed up your automation goals

Top 10 Testing Tools and Libraries for Java Developers [UPDATED]

6. Spock Framework

Spock is another testing and specification framework for Java and Groovy applications. It's written in Groovy which makes it very expressive and to the point specification language.

When you use Spock, your test will become more readable and easier to maintain, and thanks to its JUnit runner, Spock is compatible with most IDEs, build tools, and continuous integration servers.

Unfortunately, I didn't find a useful course to learn the Spock framework but Java Testing with Spock book is a good resource to start with.

book to learn Spock Framework

7. Cucumber

Cucumber is another great tool for automated integration tests but what makes it different from other tools in the same category is its specification capability.

Cucumber merges specification and test documentation into one cohesive whole living documentation and since they will be automatically tested by Cucumber, your specifications are always banged up-to-date.

If you want to build a start to finish web automation testing framework and simulate user behavior on a web application then Selenium WebDriver with Java & Cucumber BDD is a good course to both learn and implement Cucumber in your project. 

best integration tool for Java applications

8. Spring Test

Spring MVC comes with a very useful test framework, which allows doing in-depth testing without even starting a web container.

It is one of the most useful libraries for writing automated tests for Spring applications. It provides first-class support for writing unit and integration tests to Spring-powered applications including MVC controllers.

There is also a Spring Test DbUnit that integrates the Spring Test framework with DbUnit and a Spring Test MVC HtmlUnit which integrates the Spring Test MVC framework with HtmlUnit.

By using these tools you can easily test your Spring MVC application in an automated way.

9. DBUnit

A database is an integral part of many Java applications, both Core Java, and Web application, and probably the biggest obstacle while doing unit testing.

It's not reliable to connect to Dev or UAT database for integration tests because anyone can change the data and schema like tables, stored procedures and it will cause your automated integration test to fail.

DbUnit is a JUnit extension that can be used to initialize the database into a known state before each integration test and ensure that the database contains the correct data.

DbUnit has its own issues, but it is a very useful tool because it helps us to separate the test data creation from the tested code.

unit testing tool for database code

10. Robot Framework

The Robot Framework is a python based, generic test automation framework for acceptance testing and acceptance test-driven development.

It is a keyword-driven testing framework that uses tabular test data syntax. You can use it to test distributed, heterogeneous applications, where verification requires touching several technologies and interfaces.

If you decide to learn this wonderful framework for integration tests then Udemy's Robot Framework Test Automation is a great resource to start with. It's a two-part course that covers the basic and advanced features of the Robot framework.

integration testing tools for Java developers

11. Postman

This is another useful testing tool for Java developers, particularly for full-stack java developers who are creating both frontend and writing APIs on the backend. Postman allows you to directly call your API and analyze the response. 

For example, you cannot only check, if your API calls are working or not but also you can examine response headers and error codes. Similarly, while sending requests you can set headers and query parameters which makes working with APIs much easier. 

Postman also allows you to save and replay your API call which means you can use it for elaborated testing. If you are a full-stack Java developer then I highly recommend you to learn this useful tool in 2024. 

If you need a course, I highly recommend Postman: The Complete Guide - REST API Testing course on Udemy by Valentine Despa. This 13.5-hour-long course is best to learn the Postman tool for  REST API testing. 

RESTful web service testing tool for Java developers

And, here is the summary and a few more testing tools for Java developers, this includes tools that test from object to interface level including performance and other benchmarks.
  • JUnit - Common testing framework.
  • TestNG - Testing framework.
  • Mockito - Creation of test double objects in automated unit tests for the purpose of TDD or BDD.
  • Apache JMeter - Functional testing and performance measurements.
  • Arquillian - Integration and functional testing platform with integration of Java EE containers.
  • AssertJ - Fluent assertions that improve readability.
  • JMH - Micro bench-marking tool for the JVM.
  • Selenide - Concise API around Selenium to write stable and readable UI tests.
  • Selenium - portable software testing framework for web applications.
  • Spock -  A groovy-based Unit test framework, good for data-driven testing. 

That's all about some of the essential unit testing and integration testing tools, frameworks, libraries for Java developers. There are many more libraries that I have not included in this list like AssertJ, Hamcrest which can help you to write beautiful and fluent tests but take things slowly.

To start with, learn a tool or library which you can use in your day-to-day work, for example, if you are working with Java UI then you should first learn Selenium because then you can focus on this tool more.

Similarly, if you are working on REST APIs then learn REST Assured. Similarly, if you are doing a lot of core Java work, then JUnit 5 is probably the first library you should look at.

It doesn't matter much about which tool to start first but make sure you spend some time upgrading your skills in this New Year.

Other Programming Resources and Articles You may like

Thanks for reading this article so far. If you like these tools then please share them with your friends and colleagues on Facebook. If you have any questions or feedback then please drop a note.

P. S. - If you are new to the Java world and want to master Java before exploring these tools and library then you can also check out this list of Top 10 Java Courses on Medium. It contains different Java courses to become an expert Java programmer.

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