Untangle code with automated testing

Of all of the tools and techniques for untangling code, the most important is automated testing.

What does automated testing have to do with the untangling of code?

Automated testing provides insurance. It provides a back-stop against which developers can make changes.

The task of untangling code, of making code readable, often requires changes across multiple modules and multiple classes. While a few improvements can be made to single modules (or classes), most require changes in multiple modules. Improvements can require changes to the methods exposed by a class, or remove access to member variables. These changes ripple though other classes.

Moreover, the improvement of tangled code often requires a re-thinking of the organization of the code. You move functions from one class to another. You rename variables. You split classes into smaller classes.

These are significant changes, and they can have significant effects on the operation of the code. Of course, while you want to change the organization of the code you want the results of calculations to remain unchanged. That's how automated tests can help.

Automated tests verify that your improvements have no effect on the calculations.

The tests must be automated. Manual tests are expensive: they require time and attention. Manual tests are easy to skip. Manual tests are easy to "flub". Manual tests can be difficult to verify. Automated tests are consistent, accurate, and most of all, cheap. They do not require attention or effort. They are complete.

Automated tests let programmers make significant improvements to the code base and have confidence that their changes are correct. That's how automated tests help you untangle code.