Understanding the effect of `--covers`

[theofidry]

Full context in infection/infection#2848.

Scenario:

• we have some source code
• we have some tests
• we execute:

vendor/bin/phpunit --covers='<value>' --list-tests

Is the following the expected result?

• For <value>=SourceFQCN: it lists only the tests covering SourceFQCN.
• For <value>=FilePathToSrc: it will list no tests
• Is the above the expected behaviour for PHPUnit from the latest down to 9.x?
• If there is a difference, for which versions of PHPUnit are you willing to fix it (if any)

Based on your answer I'll double check the results and come up with reproducer.

[sebastianbergmann]

Combining --list-tests with a filter such as --group or --covers (which under the hood uses --group) was not possible before PHPUnit 11.1 and #5720.

[theofidry]

I see, I can confirm that executing the tests at least works.

I got it correctly on PHPUnit 9.x because I somehow ended up using attributes there instead of annotations...

• PHPUnit 9.x seems to accept multiple --covers, but effectively only picks up the last one.
• PHPUnit 10.x does not execute any test if the FQCN is a function and not a class (I didn't check traits)
• PHPUnit 10.x picks up the last --covers like 9.x but also issues a warning Option --covers cannot be used more than once
• PHPUnit 11+ accepts multiple --covers and works fine with functions (didn't check traits)