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Whether you're a seasoned Java programmer or a Java neophyte, testing Java applications is important. It ensures your application does what it's supposed to.
Fortunately, there are plenty of automated testing tools for Java. In fact, there are so many it can be difficult to know which tools to adopt and use. To help solve that dilemma, we'll discuss some of the most useful automated testing tools for testing various aspects of Java applications.
Types of Java testing tools
It's important to note not all testing tools are designed to serve the same purpose. There are multiple types of testing associated with Java applications:
- Unit testing helps you test newly written code before it is integrated into your codebase.
- Integration testing ensures that new code will not break other parts of the application.
- Performance and user experience testing verify your application is sufficiently responsive, stable and user-friendly.
- Security testing helps identify security vulnerabilities in Java code.
(This list is admittedly not completely inclusive. We haven't mentioned system testing and acceptance testing, for instance, although these overlap somewhat with performance and user experience testing.)
Some automated testing tools for Java support only one type of testing, but many can actually support multiple categories of test automation.
Best automated testing tools for Java
GitHub hosts nearly 2,000 repositories with the term "java testing" in their name. Not all of those correspond to distinct tools, but it gives us an indication of just how many automated Java testing tools are out there.
So which tools should you learn? Here's a quick guide through the valuable automated testing tools for Java applications.
As its name implies, JUnit is a Java testing tool designed for unit testing. It's probably the most widely used unit testing tool for Java applications.
On its own, JUnit is not useful for much beyond unit testing. However, you can use it in conjunction with other Java testing frameworks to help automate other types of testing, like integration and acceptance tests. You can even use it in conjunction with Selenium.
TestNG is a general-purpose Java testing tool that supports a range of test categories: unit tests, functional testing, integration tests and more. As such, TestNG is a versatile tool to have in your Java testing arsenal.
JTest is a Java testing tool that has been around for more than twenty years. Like TestNG, it is designed to support a broad set of test types. It's another useful all-around Java testing tool to have on hand.
What makes JTest particularly interesting, however, are its static analysis features. You can use them to detect performance problems and security vulnerabilities within Java applications. Few other general-purpose Java testing tools extend into these testing categories.
The Grinder is a load testing and performance testing framework for Java. It helps to ensure that Java applications can handle the traffic that deployment teams intend to throw at them. You write your test scripts in Python -- specifically, the Jython implementation -- which makes Grinder an ideal Java testing tool for performance testing.
Gatling is another Java performance testing tool. It uses a domain-specific language (DSL) for test scripts, which is one major difference between Gatling and The Grinder. Gatling also provides detailed performance testing summary reports. If you're someone who likes having analytics data summarized in graphs and charts, you'll like Gatling.
Selenium is the most widely used tool for interface and user experience testing. It supports tests on virtually any of the major web browsers, as well as Linux, macOS and Windows.
To test modern Java applications efficiently, you often need to take advantage of mocking. Mocking lets you simulate external resources to see how they interact with your application. You can therefore test your application as if it were running in a real-world environment, but without having to set up an actual environment.
Mockito is one of the leading mocking frameworks for Java testing. Used in conjunction with a unit testing tool like JUnit, Mockito makes it fast and easy to write automated Java tests.
If you want to take advantage of mocking but find Mockito overly complicated or limited in functionality, PowerMock can help. PowerMock is a unit testing framework for Java that extends the functionality of Mockito -- as well as EasyMock, another mocking tool. It lets you do things that Mockito can't, like mocking of static methods.
Arquillian is a somewhat lesser known, but quite interesting, automated testing tool for Java. Arquillian's goal is to allow developers to test on a large scale without mocking.
Instead, Arquillian lets you write tests that execute in real runtime environments. The idea is to provide the flexibility and efficiency associated with mocking, while delivering the accuracy of tests performed in real environments.
This approach can seem a bit unorthodox to old-school Java developers, but it can prove valuable.
The list above is by no means exhaustive. There are many other automated testing tools for Java out there. And the best Java testing tool for you will depend on your needs and preferences, of course. But it always helps to familiarize yourself with some of the handiest tools for various kinds of testing with Java applications.