Add composer test script

[DominicImhof]

No description provided.

[pyrech]

Hi,
Thank you for this PR but I'm not sure to understand what are the advantages of a test script?

[MaxGfeller]

+1 for this.

Composer supports defining custom scripts. Major PHP projects started adapting this and are now all defining their own test scripts. Here are some examples:

https://github.com/composer/composer/blob/master/composer.json#L63-L65
https://github.com/Seldaek/monolog/blob/master/composer.json#L60-L63

The advantage of this is pretty obvious; you don't have to have a global phpunit/whatever setup and can just run composer test for each library that you want to start working with.

I have written an article about this a while ago, if it interests you.

[paulmallet]

👍

[pyrech]

Thank you for your explanations @MaxGfeller. If this is becoming the standard, let's merge it. :)
Thank you @DominicImhof for your PR.

[MaxGfeller]

Awesome, thank you @pyrech and @DominicImhof! :)