Wednesday, September 28, 2011

If product quality is important, test code quality is too

I mean no disrespect to devs when I write this: test code can get even more complex than product code because of the larger number of dependencies to manage from tests perspective. If a product has N deployment modules, and M external dependencies, then Test has N + M external dependencies! Changes in any one of these dependencies can create a maintenance work item in the test code. The product is just being developed, too, so many changes are going on which sometimes cascade down the stack to test code. Even subtle changes in business rules might require changes to test oracles or simpler verification checks.

Readability and maintainability are therefore even more important to test code than they are to product code.

As with product code, test code should be self-documenting where possible, but that’s not sufficient: comments are good to have, where they help, at a level of abstraction higher than the code or pattern itself. This is important for product code of course, but even more so for test code, because of increased complexity and that coding skills tend to be very variable across members of the test team who write code.

With test code, the executables won’t ever be far from the source code, so information hiding (e.g. not showing a stack trace to end-users) isn’t an issue. Performance isn’t nearly the issue that it is with product code for many applications (other than maybe perf test code). So, log details on what’s going on! Strongly-typed log entries e.g. using enumerated types or XML are precise enough for automated parsing. Exceptions are a great tool, and you can make them even better

There are also lots of great tools out there to help with logging to one or more streams in a structured way. Consistency and structure make logged information more valuable and more extensible.

Do you have a favorite logging technique or tool?

Do you have a favorite strategy for test code?

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