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digitalmars.D.bugs - [Issue 18377] New: -cov LOC is inadequate for 1 liner branching;


          Issue ID: 18377
           Summary: -cov LOC is inadequate for 1 liner branching; need a
                    metric based on branching
           Product: D
           Version: D2
          Hardware: x86
                OS: Mac OS X
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: timothee.cour2 gmail.com

`dmd -cov -run main.d` shows 100% coverage; this is misleading since a branch
is not taken:

void main(){
  int a;
  if(false) a+=10;

how about adding a `-covmode=[loc|branch]` that would allow either reporting
LOC coverage or branch coverage?

branch coverage would report number of branches taken at least once / total
number of branches.

It would not only address the above issue, but it is IMO a much better metric
for coverage, less sensitive to 'overcounting' of large blocks in main code
branches (size of code block in a branch is irrelevant as far as testing is
concerned); eg:

int fun(int x){
    return fun2();  // accounts for 1 LOC and 1 branch
  // long block of non-branching code here... // accounts for 10 LOC and 1

NOTE: branches would include anything that allows more than 1 code path (eg:
switch, if)

Feb 05 2018