IncrementInteger and preg_match_all

[mfn]

Hi there,

infection n00b newcomer here 😄

If an existing (much more complex) regex I use like this (very simplified example, no errors checks etc.):

function foo($a) {
  if (preg_match_all("/(\d)/", $a, $m)) {
    return $m[0];
  }
  return [];
}

foo("1234");

var_dump of $m in the positive if branch:

array(2) {
  [0]=>
  array(4) {
    [0]=>
    string(1) "1"
    [1]=>
    string(1) "2"
    [2]=>
    string(1) "3"
    [3]=>
    string(1) "4"
  }
  [1]=>
  array(4) {
    [0]=>
    string(1) "1"
    [1]=>
    string(1) "2"
    [2]=>
    string(1) "3"
    [3]=>
    string(1) "4"
  }
}

My problem: the IncrementInteger mutator change the code to $m[1];:

---     return $m[0];
+++     return $m[1];

But how can I "fix" this, i.e I don't see what test could cover this.

Thanks! 🙏

[maks-rafalko]

Hi, on your example, $m[0] returns 1 while $m[1] returns 2, so we can write a test that checks exact value.

If it doesn't matter which integer value is returned, then probably you can do the following:

1. replace return $m[0] with current($m). IncrementInteger mutator in this case won't be applied
2. Ignore IncrementInteger mutator in this method or even line of code. See how: https://infection.github.io/guide/how-to.html#How-to-disable-Mutators-and-profiles

[mfn]

Hi, on your example, $m[0] returns 1 while $m[1] returns 2, so we can write a test that checks exact value.

Apologies I don't follow here 😅 $m[0] and $m[1] return the exact same array of 4 string (integer looking) values.
But…

2. Ignore IncrementInteger mutator in this method or even line of code

Thanks, this is what I ended up doing for now!

I'm not sure I like to use current() but I think I understand what you're trying to see. If I use a method like array_value_first it would also be safe, unless there's a mutator turning it into a fictional array_value_last or so 😅

Thank you 🙏

[sanmai]

If you won't use the parentheses as in "/\d/" you won't have $m[1] and the test would fail on this change.

[mfn]

Thanks, I'm ware of this behaviour.

In reality the regex is super complex and I don't dare to touch it; so I'll definitely stay with ignoring it

But thanks for pointing this out again, I'll remember this the next time and maybe can improve this then 👍