Error response when fields could not be found
No need for Try::Tiny when checking if fields were returned.
add File method to detect test directories
exclude modules defined under a test directory from the index
rename in_test_directory to is_in_test_directory
change is_in_test_directory to use split & any instead of regex
return empty string instead of 0 from is_in_test_directory
change File->is_in_test_directory to use ok instead of is