This is a really basic in memory file system. All files are created in RAM using malloc, so it will not persist when unmounted.
You can test out a simple FUSE filesystem like this:
$ mkdir testdir
$ ./hello testdir
$ ls testdir
hello
$ cat testdir/hello
hello, world
$ fusermount -u testdir
$ rmdir testdirTo use the debugger
$ mkdir testdir # if necessary
$ gdb hello
[gdb noise]
(gdb) [set breakpoints, etc.]
(gdb) run -s -d testdirTo run the tests
$ ./run_tests.sh