Testing a library against a runtime without mbstring is not longer possible in 8.5.18 and newer

[stof]

bf56acb introduced an early check aborting if mbstring is missing (alongside other extensions for which I don't have issues as they are necessary for PHPUnit to work).
However, the mbstring dependency of PHPUnit is a bit special: it is only necessary for the --testdox output. Using a different output (the default one for instance) does not need it.

We were relying on that in the scssphp project to run a CI job with mbstring disabled, to ensure that our library was still compatible with runtimes that don't have mbstring (using --ignore-platform-req=mbstring in Composer to skip this requirement), which was working fine on older versions.

Would it be possible to change the mbstring to happen only if the testdox output is used instead ? The original issue #4720 was only requesting a check in that case too.

[sebastianbergmann]

However, the mbstring dependency of PHPUnit is a bit special: it is only necessary for the --testdox output. Using a different output (the default one for instance) does not need it.

That is not correct:

• https://github.com/sebastianbergmann/phpunit/blob/8.5.19/src/Util/Xml.php#L25
• https://github.com/sebastianbergmann/phpunit/blob/8.5.19/src/Framework/Constraint/StringContains.php#L12

To me, the mbstring extension is not optional.

[stof]

hmm, indeed, I forgot that our testsuite also does not use the StringContains constraint (and that we use UTF-8 for our XML config file so we don't need the encoding conversion)