April 6, 2018

...Learn TDD with Codemanship

Could Refactoring (& Refuctoring) Help Us Test Claims About Benefits of Clean Code

One of the more frustrating things about teaching developers about code craft and "Clean Code" is the lack of credible hard evidence from respectable sources about the claimed benefits of it.

Not only does this make code craft a tougher sell to skeptics - and there was a time when I was one of them, decades ago - but it also calls into question whether the alleged benefits are real.

The biggest barrier to doing research in this area has been twofold:

1. The lack of data points. Most software engineering academic studies take data from a handful of projects. If this were, say, medical research, we'd never get our medicines on to the market.

2. The problem of comparing apples with apples. There are so many factors in software development that it's pretty much impossible to isolate one and rule out all others. Studies into the effects of adopting TDD can't account for the variations in experience and ability, for example. Teams new to TDD tend to have to deal with a steep learning curve before they become productive again.

When I consider some of the theories about what makes code harder to change - the central plank of the code craft thesis - some we have strong evidence to back them up, others... not so much.

I've had a bit of a brainwave in this area that might help researchers. Take a code base, then specifically vary it along a single dimension. e.g., refactor to remove duplication, or "refuctor" to introduce duplication (by inlining functions and modules). The resulting variants should all be functionally equivalent, but you could fine-grain the levels of variation. Then ask developers to make changes to the logic, and measure how much code had to be edited to achieve those changes. Automated acceptance tests would ensure that every change was logically equivalent.

I can easily envisage how refactoring (and it's evil twin, refuctoring) could be used to vary readability, complexity, duplication, coupling and cohesion (e.g., by moving methods between classes to introduce or eliminate feature envy), "swabbability" (e.g., by introducing dependency injection, or by reversing the dependency inversion by using explicit references to concrete implementations of interfaces) and a range of other code qualities. Automated tests could ensure that every variant still works exactly the same way on the outside.

And the tests themselves could be varied. For example, you could manipulate test suite execution time so that in some cases developers had to wait an hour for feedback, while others only need wait seconds for the same feedback.

I think I might be on to something. What do you think?

Posted 2 weeks, 4 days ago on April 6, 2018