Darke Files isn't available for MacOS yet. I'll make sure to understand how MacOS' file system works (especially the meta data) before working on a MacOS port. If you can provide me with more info about that test suite I would be very interested.
Right now version history of a repository is saved in a ".darke" directory that works quite similar to Git's ".git" directory. I've got a few experiments planned to improve on that system, how well it can be incrementally backed-up is a metric I will also consider.
That Darke Files does not change your files at all is one of the core principles. The same will be true for symbolic links. I'm not handling symbolic links quite yet; I've been bitten by Git's not-good-enough handling of symbolic links on Windows before.
https://github.com/bcpierce00/unison
I'd love to see Darke Files get everything right that Unison gets right, that nearly all commercial projects get wrong, through a blend of arrogance and ignorance:
* Meta data. It takes a lot to insure that two copies of a MacOS file appear identical to a user. There used to be a test suite on the web that embarrassed everybody.
* Atomic folders such as ".git" or an application bundle. A prototypical example is a MacOS disk image, supported by a folder of many small files. This makes incremental backup and transfer more efficient, assuming a single source. Unison lets you specify the conflict resolution at the folder level, all-or-nothing decide which copy or fix it.
* Symbolic links. This is wildly complicated by users, sure they're right, who want special handling to hack features into sync software that isn't there. A symbolic link is just a file, with correct use the responsibility of the user. You wouldn't want sync software stopping to view your porn, right? They're just files, not the sync software's business.
I use Dropbox for various purposes because I need to, but they bungle more of this than one would expect. For example, a typical MacOS application bundle can have internal symbolic links a typical user never notices, pointing the "current" version of resources to a versioned folder. Last I checked, Dropbox expands the symbolic link into a redundant copy, wasting space without kneecapping the app.
One could go on...