What I usually do is point my phpunit testing framework on PHPStorm to the secret .phpunit directory which was created by the bridge, like:

The location of the “phar” file is:
bin/.phpunit/phpunit-(major).(minor)/phpunit
or in some cases:
vendor/bin/.phpunit/phpunit-(major).(minor)/phpunit
After this, the specified phpunit executable will be called correctly when exeuting unit-tests, but with a --no-configuration option. This can cause autoloading problems (a lot of “class not found” errors), because the autoloader generated by Composer is not specified anywhere.
To fix this, you should have a phpunit.xml file in your project (this is common practice anyway), in which you specify Composer’s autoloader, something like this:
<phpunit bootstrap="vendor/autoload.php">
This phpunit.xml should then be specified in the “Default configuration file” option and you should be good to go.
Regarding phpstorm using phpunit-bridge:
It’s possible as a custom script, but you won’t have the nice interface and the possibility to run (and debug) specific tests via PHPStorm interface.