Wrong branches count

[stereobooster]

• Version: v20.13.1
• Platform: 23.1.0 Darwin Kernel Version 23.1.0: Mon Oct 9 21:27:27 PDT 2023; root:xnu-10002.41.9~6/RELEASE_X86_64 x86_64

This code shows 75% (3/4) branches coverage

export function comp(a, b) {
  if (a === b) {
    return 0
  } else if (a > b) {
    return 1
  } else {
    return -1
  }
}

comp(1, 1)
comp(1, 0)

This code shows 75% (3/4) branches coverage:

export function comp(a, b) {
  if (a === b) return 0;
  else if (a > b) return 1;
  else return -1;
}

comp(1, 1)
comp(1, 0)

But this code shows 80% (4/5) branches coverage:

export function comp(a, b) {
  if (a > b) return 1;
  if (a < b) return -1;
  return 0;
}

comp(1, 1)
comp(1, 0)

Istanbul shows 75% for all examples.

PS maybe you know how branches counted? To me it seems that there are 3 branches

[stereobooster]

Probably consequence of #172

[cenfun]

Try c8 --experimental-monocart

// example.c8.js
export function comp(a, b) {
  if (a > b) return 1;
  if (a < b) return -1;
  return 0;
}

comp(1, 1)
comp(1, 0)

c8 --experimental-monocart node example.c8.js
---------------|---------|----------|---------|---------|-------------------
File           | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
---------------|---------|----------|---------|---------|-------------------
All files      |   88.88 |       75 |     100 |     100 | 
 example.c8.js |   88.88 |       75 |     100 |     100 | 4
---------------|---------|----------|---------|---------|-------------------

Or try native V8 coverage reports

c8 --experimental-monocart --reporter=v8 --reporter=console-details node example.c8.js
┌───────────────┬─────────┬────────────┬──────────┬───────────┬─────────┬─────────────────┐
│ Name          │   Bytes │ Statements │ Branches │ Functions │   Lines │ Uncovered Lines │
├───────────────┼─────────┼────────────┼──────────┼───────────┼─────────┼─────────────────┤
│ example.c8.js │ 92.70 % │    88.89 % │  75.00 % │  100.00 % │ 85.71 % │ 4               │
├───────────────┼─────────┼────────────┼──────────┼───────────┼─────────┼─────────────────┤
│ Summary       │ 92.70 % │    88.89 % │  75.00 % │  100.00 % │ 85.71 % │                 │
└───────────────┴─────────┴────────────┴──────────┴───────────┴─────────┴─────────────────┘

[stereobooster]

Thanks. I wasn't aware of it