optimizationkotlinsonarqubecode-readability

What is Cognitive Complexity in sonar report?

Now a days i switched to sonar reports for static code review and performance improvement. Under the rules section I found that the cognitive complexity of my methods are high.

You can find cognitive complexity error in sonar as: Go to Project->Issues Tab->Rules Drop-down->Cognitive Complexity

Below screen shot gives you a reference of sonar project:

enter image description here

I was not getting any way to calculate and reduce the cognitive complexity of my methods. Finally I found the accurate way to calculate the complexity and i will answer this in my post below. Please check out.

Solution

  • Cognitive Complexity

    After searching some blogs and having chat with sonar team I found an easy definition and calculation of cognitive complexity which is as below:

    Definition:

    Cognitive Complexity, Because Testability != Understandability

    Your written code must be as simple to understand as the above definition, simple.

    less Cognitive Complexity more Readability

    Let's see a method for example to calculate CC, right now I am referring kotlin language, see below image:

    Sonar capture

    In above image there is a method getAppConfigData(), whose cognitive complexity is being measured. Right now the CC of this method is 18. As you can check in above screen shot there is a warning, which tells that the limit of maximum complexity is 15, which is lower than the current CC of this method.

    Now the actual question is: How can I calculate the CC of my method at the time of development?

    Follow below rules to get your CC of any method or class as:

    So whenever above rules matches, just add + count to your CC and remember count will be increased according to level of code break, as example "if" condition gets +1 if it is the first code break but if you have used one more nested if then it will be a +2 for that inner "if" as shown in below image.

    enter image description here

    That's all I got in terms of Cognitive Complexity.

    You can find everything related to CC at sonar blog

    Thank You