fixed autoloading of unit test classes
minor #568 fixed autoloading of unit test classes (fabpot)

This PR was merged into the 5.3-dev branch.

Discussion
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fixed autoloading of unit test classes

It works by chance (as PhpUnit load all files/classes in alphabetical order and abstract classes are loaded first), but when trying to run a single unit test, it might break without this fix.

Commits
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3657ef0 fixed autoloading of unit test classes