Test Code Generation

Yesterday I started evaluating a product that claims to be able to generate test code for you. As a Java developer, I am mainly interested in JUnit test code. I am a big believer in test driven development, but I often find myself inheriting code with low test coverage. So, the question is, are there tools out there that can help one quickly and painlessly generate test cases for under-tested code?

In a past job I used a product called AgitarOne that purported to do just this sort of thing. The tests that were generated, of course, captured the current functionality whether correct or not. It could not produce truly intelligent test code. Also, it was big and expensive and required a lot of resources. Worse yet, generated tests extended a proprietary class, so the more you used it the more you were locked into their product.

I tried to use a free tool called testgen4j, but I didn't have the patience to make it work. Its user interface is a Unix shell script. I tried running it under Cygwin, but found the script didn't like being run with JAVA_HOME set to something with "C:" in it. I may eventually try it again, but what I really want is something that runs as an Eclipse plugin.

With that in mind, I started googling, and I found something called CoView. This product offers a Community Edition and an inexpensive Premium License. I downloaded and installed the community license file and the Eclipse plugin. However, to my disappointment, it simply did not work. It got errors whenever I tried to go to the preference page to tell it about the license file.

With a little more googling, I found CodePro AnalytiX. This is a much more expensive product, but I thought I might as well try the 15 day evaluation. It turns out that AnalytiX is just what I would like to have. It runs as an Eclipse plugin, it does a fair job of generating test code, it uses EasyMock, and it does not rely on some proprietary base class.

Unfortunately, when I set the CodePro preference to always generate mocks for all interfaces, this caused it to generate some code that wouldn't compile due to duplicate local variables. Selective use of mock objects worked better.

I had a number of classes that extend JdbcDaoSupport. Even after enabling generation of Spring tests, CodePro couldn't generate usable tests for these classes. The generated tests all had comments that said: "An unexpected exception was thrown in user code while executing this test...".

I guess the bottom line is that these kinds of tools can be nice, but even the really expensive ones will never generate usable tests for all code much less optimal, intelligent tests. They are largely a crutch for people who do not have the discipline to do proper test driven development, and, unfortunately, not a good solution to low coverage on legacy code.