I typically put such files in the t directory, and start the test files with something like: 
BEGIN {
    chdir '..' unless -d 't';
}
use t::Whatever;

[download]
or 
BEGIN {
    chdir 't' if -d 't';
}
use Whatever;

[download]
or 
BEGIN {
    chdir '..' unless -d 't';
}
push @INC, 't';
use Whatever;

[download]
Now that only allows you to run the tests either from the 't' directory, or the top-level distro directory (using either "make test", "prove", or a path to the test file), but I've never felt the urge to run the tests from any other directory.

In reply to Re^3: Share code among tests by JavaFan
in thread Share code among tests by ambrus

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