Tools For Unit Testing Java Web Applications

As a java developer, I write unit tests all the time. There are a lot of ways to do this, but sometimes unit testing becomes difficult. This could be because you need to test a Struts action or you do not want your unit tests to hit your database. So, the question is what tools can you use for testing java web applications? This is not meant as a complete and thorough overview, just some of the tools I know of or have looked into at some time. In many cases, you will find that your testing code is very repetitive, so you may end up building frameworks on top of these frameworks. I am sure I missed something or maybe even your favorite, so just leave me a comment.

Basic Java Testing – JUnit and TestNG are the most popular tools for basic java unit testing. JUnit typically has a small advantage as it has been around longer and is included with most packages of Eclipse. However, I do not think one is really better than the other, they are just different.

Mock ObjectsEasyMock and jMock are popular mock objects frameworks. Sometimes you have to simulate the way another system works, and mock objects are perfect for this. You can even create your own mock object, but the frameworks make it easy to avoid extra code.

Database InteractionDBUnit is really the only decent framework I have seen. It allows you to insert data before the test is run and cleans up after the test is complete. However, capturing the appropriate data for a test is not simple for anything but the most trivial applications.

User Interface Testing – UI testing is notoriously difficult and many applications skip it entirely. If you are testing your generated html, you will want to look at the following tools and determine which best suits your needs. This is a special case, as there is no “one true way” to test the user interface. These are all free tools as I am a fan of keeping things as cheap as possible if the tools are good enough.

  • Selenium – Maybe the most complete package of the bunch and supports testing in IE, FireFox and Safari. Your unit tests are written in java, so you just need to learn the API. They also have interesting server options where you can run your tests across servers. You can even record tests using a FireFox add-on.
  • Canoo WebTest – This is another framework that can record tests with a FireFox add-on. The tests for WebTest are typically written in xml files. This gives you the option to build a library of fragments of functionality to include in various tests. You can also write your tests in Groovy or use the Java API directly. These can also be run directly from within Ant.
  • Watij – This is a port of the popular Ruby testing framework, Watir. The tests are written in Java using their API. They also include BeanShell so that you can interactively test your code. This is a really interesting option if you are not sure what a unit test should look like initially.
  • JWebUnit – This is more of a meta-framework, where it can build upon HtmlUnit or Selenium. HtmlUnit is fairly good by itself, but sometimes a framework is just too low-level for some people or people find that they keep doing the same things and decide to build upon the framework. There is one problem with JWebUnit, the documentation is very sparse, so the learning curve ciould be problematic.
  • Cactus – This is another meta-framework, but this is from Apache. It is meant as a wrapper for testing an entire application from basic java testing, servlet testing and down to the user interface testing. Due to this meta concept, the documentation can be a bit vague. However, I have heard good things from those people that spent the time to learn more. Disappointingly, I have not had the time to dive into it much.

There are a lot of other tools out there as well. FitNesse is very popular, but it takes a very distinct approach to how unit tests are built. For Struts applications, there is a framework called StrutsTestCase that is immensely helpful as well. For a big list of testing and related software, take a look at They list testing frameworks for almost every language. Lastly, it is always a good idea to know how well your software is tested. This is not a question of whether all of your tests pass, but how much of the code is actually tested. My favorite test code coverage tool is Cobertura. It is fairly simple to use and the reports are generated in a similar manner to how JUnit generates reports.

So, if you know of a good free java testing tool, drop me a note in the comments. Sometimes a good tool may not be getting enough publicity or I may not have had time to look at it. In any case, keep testing until you have good test coverage. And remember the testing mantra, “Red, Green, Refactor” 🙂

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