The script was tested and ran in

$ php -v
PHP 7.1.8-2+ubuntu16.04.1+deb.sury.org+4 (cli) (built: Aug  4 2017 13:04:12)

But it should also run in Windows and with lower versions of PHP (5.6+). The major concern is the version of PHPUnit to run the tests.

To run, execute

$ $ php balance.php "<string to test>"

For example the following script returns 2

$ php balance.php "{}}"
2

If no string is given to the script, the script displays an error message with instructions.

The script can be tested using PHPUnit. A PHPUnit phar file is included in the repo for convenience.

To run the tests simply do:

$ ./phpunit.phar tests.php

Should output:

PHPUnit 6.4.3 by Sebastian Bergmann and contributors.

......                                                              6 / 6 (100%)

Time: 187 ms, Memory: 10.00MB

OK (6 tests, 6 assertions)

Any concerns, questions or suggestion please email me at [email protected]