rspec/rules/S3776/why.adoc
2024-01-29 14:28:14 +01:00

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Cognitive Complexity is a measure of how hard it is to understand the control flow of a unit of code.
Code with high cognitive complexity is hard to read, understand, test, and modify.
As a rule of thumb, high cognitive complexity is a sign that the code should be refactored into smaller, easier-to-manage pieces.
=== Which syntax in code does impact cognitive complexity score?
Here are the core concepts:
* **Cognitive complexity is incremented each time the code breaks the normal linear reading flow.** +
This concerns, for example, loop structures, conditionals, catches, switches, jumps to labels, and conditions mixing multiple operators.
* **Each nesting level increases complexity.** +
During code reading, the deeper you go through nested layers, the harder it becomes to keep the context in mind.
* **Method calls are free** +
A well-picked method name is a summary of multiple lines of code.
A reader can first explore a high-level view of what the code is performing then go deeper and deeper by looking at called functions content. +
__Note:__ This does not apply to recursive calls, those will increment cognitive score.
The method of computation is fully detailed in the pdf linked in the resources.