TestCase::setLocale() resets LC_ALL locale without respecting format

[SiebelsTim]

Q	A
PHPUnit version	main, 9.6.3
PHP version	8.1
Installation Method	Composer

Summary

When using TestCase::setLocale in combination with \LC_ALL, PHPUnit does not reset the locale properly.
In the worst case, it throws a warning which stops the test:

setlocale(): Specified locale name is too long

Current behavior

Here, PHPUnit saves the currently used locale with setlocale($category, 0).

phpunit/src/Framework/TestCase.php

Line 1080 in e00f0fe

$this->locale[$category] = setlocale($category, 0);

Then, it tries to reset the locale based on what was saved.

phpunit/src/Framework/TestCase.php

Line 1790 in e00f0fe

setlocale($category, $locale);

However, when we use \LC_ALL and it contains something other than C, setlocale(\LC_ALL, 0) returns a list of key-value pairs separated by semicolons.

https://3v4l.org/BNNQu

Therefore, PHPUnit tries to reset the locale for \LC_ALL with an invalid value.

How to reproduce

class MyTest extends TestCase {
  function testStuff(): void {
    setlocale(\LC_NUMERIC, 'en_US.utf8'); // To get a list of key-value pairs

    $this->setLocale(\LC_ALL, 'en_US.utf8');
  }
}

Expected behavior

No error.
Locale reset to the previous value.

[sebastianbergmann]

When you master you mean main, I assume. So the problem exists in both PHPUnit 9.6 and PHPUnit 10.0. Correct?

[SiebelsTim]

When you master you mean main

Yup, sorry!

So the problem exists in both PHPUnit 9.6 and PHPUnit 10.0. Correct?

Yes. I tested PHPUnit 9.6. Then I looked into the source code to confirm that it is not fixed. However, I did not run PHPUnit 10.

[sebastianbergmann]

Thank you for reporting this issue. However, I am afraid that I won't be able to dedicate time to debugging/fixing it. I will, of course, review and consider a pull request that addresses this.

Here is why I am reluctant to look into this: I am considering to deprecate functionality such as TestCase::setLocale() in a future release, and then remove it in the next major version after that. I consider this functionality to be "niche" as I have not seen used it being used so far.

[sebastianbergmann]

The TestCase::setLocale() method is deprecated and scheduled for removal, see #5216 for details.