Exclude tests from package distribution

[neomerx]

Currently if phpunit is installed as a project dependency, composer downloads it with tests and some other not necessary files. And some of the phpunit names get IDE code helpers messy

The solution is to instruct git/composer to ignore some of the files and folders by adding to .gitattributes a list of files/folders

/tests              export-ignore
/.gitattributes     export-ignore
/.gitignore         export-ignore
/.php_cs            export-ignore
/.travis.yml        export-ignore
...

[alcohol]

This does break the install process for anyone installing phpunit from github zipballs and attempting to install the dependencies using Composer, because of the explicit classmap reference in autoload-dev to the tests directory. Possible solutions here would be to switch to using PSR-0/PSR-4 instead of classmap (if this is something that you would want to address).

[sebastianbergmann]

@alcohol If you think that this breaks something that should not be broken then please open a new ticket.

Also note that this is not in any release yet. So if you it breaks something for you then because you are not using a stable release of PHPUnit.