What is cyclomatic complexity ?

Testing is the process by which all the code should be executed once to identify the bugs/errors in a product/system.
In testing there is a concept called cylomatic complexity through which we can identify all the executable path/flow.

Will it be useful only for testing ?

  while testing, we can try with all inputs which satify all the executable paths in a code.
we have to test with all the inputs which will cover all the executable paths. This will ensure that
code in a product/system executed only once.

Will it be useful for development?

It will be useful for enhancing the existing product/integrate new components to the existing product. On such a development case,
we can idenfity the executable paths and inputs. After the enhancement/adding new component, we can test with previously identified executable paths and inputs also we have
to add new executable paths and inputs for the  addition of new components/enhancements.