bootstrap.php breaks when running PHPUnit

[cameronmurphy]

On a vanilla install of Symfony 4.2, running PHPUnit fails with the error Undefined index: APP_ENV. I traced the issue down to the use of elvis operators instead of null coalesce operators (used on the next line) in config/bootstrap.php.

I was able to resolve by changing

$_SERVER['APP_ENV'] = $_ENV['APP_ENV'] = $_SERVER['APP_ENV'] ?: $_ENV['APP_ENV'] ?: 'dev';

to

$_SERVER['APP_ENV'] = $_ENV['APP_ENV'] = $_SERVER['APP_ENV'] ?? $_ENV['APP_ENV'] ?? 'dev';

in config/bootstrap.php.

Steps to reproduce (tested with CentOS 7, PHP 7.2.13, Symfony CLI 4.2.2)

$ symfony new --full test
$ cd test
$ bin/phpunit

[xabbuh]

Same as symfony/symfony#29771?

[ro0NL]

Confirmed. Using ?: doesnt handle undefined indexes: https://3v4l.org/MvGV0

Updated from 4.1 to 4.2 and run into same problem.

[weaverryan]

You didn’t have the issue on 4.1? This looks legit - but my guess is that it should affect all versions that have this code.

[Pierstoval]

What about using empty() which should handle undefined indexes?

[fabpot]

empty() should never be used.

[Pierstoval]

Any particular reason for that?

[javiereguiluz]

@Pierstoval we (usually) don't use empty() in Symfony code because most of the times you want to only check null === ... and not empty strings or zeros. Sometimes you want to test everything ... but empty() is too "liberal" and that's why we usually prefer to be explicit in the conditions.

[weaverryan]

See #513

[AkashicSeer]

Alright so how do I fix this?

[gmsantos]

@AkashicSeer are you having the exact same issue? Didn't #513 worked for you?