I’ve previously written about the benefits of experimental programming: fixing code until all tests pass without necessarily understanding at a theoretical level why they pass. This scares the bejeezus out of a lot of developers, but I’m convinced it’s going to be increasingly necessary as software grows more and more complex. The whole field of genetic algorithms is just an extreme example of this. Simulated annealing is another. However those techniques are primarily used by scientists who are accustomed to learning by experiment before they have a full and complete understanding of the underlying principles. Computer scientists are temperamentally closer to mathematicians, who almost never do experiments; and who certainly don’t trust the results of an experiment unless they can prove it theoretically.

However, perhaps it’s possible to introduce experimental programming in a slightly less controversial form. While many programmers may be unwilling to accept it as positive evidence of program correctness, it can offer undeniable evidence of program failure. This was recently brought to mind by a bug I was trying to fix in Jaxen.

This entry was posted on Thursday, September 21st, 2006 at 6:00 am and is filed under Testing. You can follow any responses to this entry through the Atom feed. You can make a comment or trackback from your own site.

There are many reasons to write your tests first. An oft unmentioned benefit is that it makes the programmer stop and think about what they’re doing. More often than you’d expect, the obvious fix is not the right answer; and writing the test first can reveal that.

For example, recently Wolfgang Hoschek pointed out that in XOM the Attribute class’s setType() method was failing to check for null. Once he pointed it out, it was an obvious problem so I opened up Eclipse and got ready to fix it:

This entry was posted on Tuesday, August 22nd, 2006 at 6:18 am and is filed under Blogroll, Testing. You can follow any responses to this entry through the Atom feed. Both comments and pings are currently closed.

While it may be a slightly too extreme position to say that tests are the only spec, I think it is absolutely reasonable to consider tests to be a major part of the spec. Indeed a specification without normative test cases is far less likely to be implemented correctly and interoperably than one with a solid normative test suite. The more exhaustive the test suite is, the easier it is to write a conforming correct implementation.

Cedric Beust presents the question, “how do you specify an exponentiation function with a test?” as a counterexample to tests as specs. Actually I don’t think it’s all that hard. Here’s one example:

This entry was posted on Saturday, July 8th, 2006 at 6:31 am and is filed under Blogroll, Testing. You can follow any responses to this entry through the Atom feed. You can make a comment or trackback from your own site.

The final chapter of the recently published Java I/O, 2nd edition focuses on the Java Bluetooth API. Like about half of what’s going on in Java today the Java Bluetooth API was defined and developed in the Java Community Process (JCP). I spend a lot of energy criticizing the W3C process, but compared to the JCP, it’s a model of sanity.

This entry was posted on Monday, May 29th, 2006 at 7:13 am and is filed under Blogroll, Open Source, Testing. You can follow any responses to this entry through the Atom feed. You can make a comment or trackback from your own site.

Here’s an interesting article that is totally, completely 180 degrees wrong. I’ve said this before, and I’ve said it again, but I’ll say it one more time: final should be the default. Java’s mistake was not that it allowed classes to be final. It was making final a keyword you had to explicitly request rather than making finality the default and adding a subclassable keyword to change the default for those few classes that genuinely need to be nonfinal. The lack of finality has created a huge, brittle, dangerously breakable infrastructure in the world of Java class libraries.

This entry was posted on Wednesday, May 24th, 2006 at 7:28 am and is filed under Blogroll, Testing. You can follow any responses to this entry through the Atom feed. You can make a comment or trackback from your own site.