Do not run SKIPIF section of PHPT test in separate process when it is free of side effects

[staabm]

while looking into PHPT performance, I realized that the --SKIPIF-- condition is evaluated in a separate subprocess.

this means a major overhead for a maybe pretty simple side-effect-less condition like:

--SKIPIF--
<?php version_compare(PHP_VERSION, "8.0", ">=")
      or echo "skip because attributes are only available since PHP 8.0"; ?>

I built a small class in which you can pass a string of source-code and it returns whether the given code would have side-effects when evaluated.

In PHPUnit I utilize the detected side-effect-free SKIPIF conditions and evaluate such code in the main-process instead of creating a new one. In case we cannot say with 100% certainty the code does not have side-effects we play save and run it in the subprocess.

---

when running php ./phpunit tests/end-to-end/event/assert-failure.phpt I can see the following results:

macos:

after this PR: 00:00.070 - 00:00.077
before this PR: 00:00.092 - 00:00.098

-> which means ~20% faster on my mac m1pro on a single test-case.

on windows with

PHP 8.3.11 (cli) (built: Aug 27 2024 21:28:35) (NTS Visual C++ 2019 x64)
Copyright (c) The PHP Group
Zend Engine v4.3.11, Copyright (c) Zend Technologies

after this PR: 00:00.360 - 00:00.395
before this PR: 00:00.406 - 00:00.443

-> seems also roughly ~20% faster
(see how slow running the same test is on windows vs. macos)

refs #5973

[staabm]

is this correct like that?

[codecov]

Codecov Report

Attention: Patch coverage is 96.87500% with 1 line in your changes missing coverage. Please review.

Project coverage is 94.78%. Comparing base (f22ea1e) to head (0db3be0).
Report is 1 commits behind head on 11.5.

Files with missing lines	Patch %	Lines
src/Runner/PHPT/PhptTestCase.php	96.87%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               11.5    #5998      +/-   ##
============================================
+ Coverage     94.76%   94.78%   +0.01%     
- Complexity     6807     6814       +7     
============================================
  Files           720      720              
  Lines         21603    21626      +23     
============================================
+ Hits          20473    20498      +25     
+ Misses         1130     1128       -2     

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[staabm]

Blogged about it: https://staabm.github.io/2024/10/19/phpunit-codesprint-munich.html