The tests require access to an FTP server. They need full access to create, read and delete directories and files. You can provide the account data via environment variables.

$ GIT_FTP_USER=kate
$ GIT_FTP_PASSWD=s3cret
$ GIT_FTP_ROOT=localhost/test_dir/   # trailing slash!
$ export GIT_FTP_USER
$ export GIT_FTP_PASSWD
$ export GIT_FTP_ROOT

Run the unit tests by executing make.

$ make

If you don't have lftp installed, the test will leave a bunch of test directories on the server. They are all named like git-ftp-XXXX. You should delete them.