Added the CI run for all OS, and it already discovered two bugs.

1. ExistCheck() sometimes returns an error when it should not

Looking at how ExistCheck is defined:

// ExistCheck return true if the path exists or false if the path doesn't exists.
// In case the check fails false is returned together with the corresponding error.

It happens that on UNIX if a file already exist, say path/to/file, and you try to Stat using file as a directory:

info, err := os.Stat("path/to/file/name")

then Stat returns an error that is NOT an os.ErrNotExist. In this particular case the error is a os.PathError with Err field set to ENOTDIR. We now explicitly check for this particular case and the test case has been updated accordingly.

After updating the test case, it passes also on Windows.

2. IsDirCheck() sometimes do return errors when it should

Looking at how IsDirCheck is defined:

// IsDirCheck returns true if the path exists and is a directory or false
// if the path exists and is not a directory. In all the other case false and
// the corresponding error is returned.

in other words:

• if the path exists and is a directory => true, nil
• if the path exists and is NOT a directory => false, nil
• if the path DOESN'T exists => false, err

This wasn't happening on UNIX (we had the same problem as 1. but with the opposite outcome).
Again after fixing this bug and updating the unit test it pass also on Windows.