Fix: Detect and fail when workers crash after test execution but before writing result files

[gpn273]

Problem

When a child process crashes unexpectedly (e.g., due to out-of-memory errors) after executing tests but before writing result/coverage files, Paratest would silently ignore the missing files and exit with code 0. This causes false-positive CI pipeline passes despite test failures.

Scenario

1. Test executes and reports error (E) in output
2. Status file is written (worker marked as "free")
3. Process crashes due to OOM before application->end() completes
4. Result/coverage files are never written
5. Paratest exits successfully (exit code 0)

Solution

Added validation to ensure all workers that executed tests have written their result and coverage files. If files are missing, throw MissingResultsException with a clear error message.

Changes

• Added WrapperWorker::hasExecutedTests() to track which workers ran tests
• Added WrapperRunner::$requiredTestResultFiles and $requiredCoverageFiles to track file paths that must exist
• Validate test result files only for workers that executed tests (not idle workers)
• Validate coverage files only for workers that executed tests and have coverage enabled
• Throw MissingResultsException with actionable error message when files are missing

Testing

• New MissingResultsException unit tests verify exception behaviour
• Validated fixes in a code base which replicates the issue which this pull request solves

Fixes

Addresses the issue where Paratest would pass CI despite worker crashes when using --passthru-php='-dmemory_limit=1G' or similar memory constraints.

Screenshot

Screenshot demonstrating the exception raising when test result files are missing for a given worker:

[Slamdunk]

This is a welcome contribution, thank you for the explanation and the fix.

I'm wondering: can we also add a test that reproduce the issue?

An idea could be to create a test that registers a shutdown function to delete the result file and the coverage file, they can be easeily gathered within the test by copy-pasting the getopt line of bin/phpunit-wrapper.php: would you be so kind to give it a try please?

[Jean85]

An idea could be to create a test that registers a shutdown function to delete the result file and the coverage file, they can be easeily gathered within the test by copy-pasting the getopt line of bin/phpunit-wrapper.php: would you be so kind to give it a try please?

Stealing from my own ideas, you could also:

• force a fatal error with an anonymous class that doesn't implement all the right methods: https://github.com/facile-it/paraunit/blob/c5bdee0de7c5292df1a0377fe6f6869f9c318177/tests/Stub/FatalErrorTestStub.php#L11
• use a simple exit() (139 is the exit code for segfaults): https://github.com/facile-it/paraunit/blob/c5bdee0de7c5292df1a0377fe6f6869f9c318177/tests/Stub/SegFaultTestStub.php#L11

[gpn273]

Thank you both (@Slamdunk & @Jean85) for your feedback.

I've added test cases that reproduce the issue using the approach you suggested.

The test fixtures register shutdown functions that find file paths from $_SERVER['argv'] (for test result files) and unserialize --phpunit-argv (for coverage files), wait for the files to be written, then delete them to simulate an incomplete application->end() call. I've added three test cases covering: missing test result files, missing both files, and missing only coverage files.

All 128 tests now pass, and the tests verify that MissingResultsException is thrown with appropriate error messages for each scenario.

[Slamdunk]

Thank you for this very well written PR 💪