Category Archives: Testing

5 Unit Testing Mistakes

When I first heard about unit testing using a framework like JUnit, I thought it was such a simple and powerful concept. Instead of ad hoc testing, you save your tests, and they can be run as often as you like. In my mind, the concept didn’t leave much room for misunderstanding.¬†However, over the years I have seen several ways of using unit tests that I think are more or less wrong. Here are 5, in order of importance:

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Unit Testing Private Methods

How can you unit test private methods? If you google this question, you find several different suggestions: test them indirectly, extract them into their own class and make them public there, or use reflection to test them. All these solutions have flaws. My preference is to simply remove the private modifier and make the method package private. Why is this a good idea? I will get to that after I discus the problems with the other methods. Continue reading

A Bug, a Trace, a Test, a Twist

Here is the story of a bug that I caused, found, and fixed recently. It is not particularly hard or tricky, and it didn’t take long to find and fix. Nevertheless, it did teach me some good lessons. Continue reading

TDD, Unit Tests and the Passage of Time

Many programmers have a hard time writing good unit-tests for code that involves time. For example, how do you test time-outs, or periodic clean-up jobs? I have seen many tests that create elaborate set-ups with lots of dependencies, or introduce real time gaps, just to be able to test those parts. However, if you structure the code the right way, much of the complexity disappears. Here is an example of a technique that lets you test time-related code with ease. Continue reading

Great Programmers Write Debuggable Code

All programs need some form of logging built in to them, so we can observe what it is doing. This is especially important when things go wrong. One of the differences between a great programmer and a bad programmer is that a great programmer adds logging and tools that make it easy to debug the program when things fail.

When the program works as expected, there is often no difference in the quality of the logging. However, as soon as the program fails, or you get the wrong result, you can almost immediately tell the good programmers from the bad. Continue reading

Book Review: How Google Tests Software

When I found out about the book¬†“How Google Tests Software“, it didn’t take long until I had ordered a copy. I find it quite fascinating to read about how Google does things, whether it is about their development process, their infrastructure, their hiring process, or, in this case, how they test their software. I am a developer at heart, but I have worked for a few years as a tester, so testing is also dear to me.

It’s quite an interesting book, and it makes some great points about the future of testing. However, despite the phrase “Help me test like Google” on the cover, it is not as useful as I had hoped when it comes to improving your own testing. Continue reading