flake8-cognitive-complexity

An extension for flake8 that validates cognitive functions complexity.

Cognitive complexity is analog of cyclomatic complexity, that measure how difficult to understand piece of code. Introduced by G. Ann Campbell and currently used by SonarSource, CodeClimate and others. You can find more readings about cognitive complexity in cognitive-complexity readme file.

Default complexity is 7, can be configured via --max-cognitive-complexity option.

Installation

pip install flake8-cognitive-complexity

Example

def f(a, b):
    if a:
        for i in range(b):
            if b:
                return 1

Usage:

$ flake8 --max-cognitive-complexity=3 test.py
text.py:1:5: CCR001 Cognitive complexity is too high (6 > 3)

Tested on Python 3.7.x and flake8 3.7.8.

Error codes