Refactor variable setting from arguments to a function
Refactor expected output away from runParallelPHPUnit
Use --filter switch to prune the list of file to test

To avoid "No tests executed!" messages in the log when you use --filter
switch in your phpunit command. Before we ran the phpunit files to all
test files found. Now we filter away from this list the test files that
don't have test methods matching the --filter switch.
Add the documentation of test file list filtering