`CoversMethod` looks bugged when trait is used

[yurii-stickee-2023]

Q	A
PHPUnit version	12.0.7
PHP version	8.3.19
Installation Method	Composer

Summary

It looks like CoversMethod is bugged when trait is used by class.
Test coverage that is reported is not complete and is very strange.
I have created repository that recreates the issue https://github.com/yurii-stickee-2023/bugged-phpunit-covers-method-with-trait

p.s.
When tests are run while trait is used, PHPUnit outputs

1) Tests\DummyWithTraitTest::test1
This test executed code that is not listed as code to be covered or used:
- /var/www/bugged-phpunit-covers-method-with-trait/src/DummyWithTrait.php:10

/var/www/bugged-phpunit-covers-method-with-trait/tests/DummyWithTraitTest.php:12

OK, but there were issues!
Tests: 3, Assertions: 3, Risky: 1.

Maybe this can be useful

Current behavior

It has very weird behavior. It makes Dummy class with test coverage while other 2 classes are left without test coverage for some unknown reason

How to reproduce

Here https://github.com/yurii-stickee-2023/bugged-phpunit-covers-method-with-trait/blob/73a82437acf414ea08422982dd68afd564c69032/src/DummyWithTrait.php#L6 in dummy class DummyWithTrait uncomment trait so it becomes

<?php
namespace App;

class DummyWithTrait extends BaseDummy
{
    use SomeTrait; // <--- THIS

    public function method1()
    {
        return __FUNCTION__;
    }

    public function method2()
    {
        return __FUNCTION__;
    }
}

Run tests (I did it with xDebug)

XDEBUG_MODE=coverage php -dpcov.enabled=0 vendor/bin/phpunit --coverage-html=.phpunit.cache/coverage-xdebug

Expected behavior

It should report 50% test coverage for all 3 classes - Dummy, Dummy2 and DummyWithTrait

If you downgrade to PHPUnit 11 like composer require --dev phpunit/phpunit:^11.0 -W you will see that it works as expected in both cases now.

[sebastianbergmann]

I can confirm that PHPUnit 11.5 (with php-code-coverage 11.0.9) and PHPUnit 12.0 (with phpunit/php-code-coverage 12.1.0) behave differently and will investigate this further.

[sebastianbergmann]

This might be related or a separate bug, but how PHPUnit 12 reports the "code that is not listed as code to be covered or used" is wrong:

This test executed code that is not listed as code to be covered or used:
- /var/www/bugged-phpunit-covers-method-with-trait/src/DummyWithTrait.php:10

In the output shown above, /var/www/bugged-phpunit-covers-method-with-trait/src/DummyWithTrait.php:10 should be App\DummyWithTrait::method1 instead.

[sebastianbergmann]

This is odd: my first attempt to reproduce this through unit tests failed (see dabbb4f).

[yurii-stickee-2023]

Good day, @sebastianbergmann

Thank you for looking into this. Unfortunately I do not know internals, but if you think I can help with some manual testing, please let me know.

Just a wild guess about why it may pass during unit testing based on your code dabbb4f
I see that it has predefined list of files to load, so it can be

1. File order that is used in unit tests
2. Usage of realpath(..) that somehow resolves into correct match

Please ignore me if this makes no sense.

Regards