fakedatafs is a file system that generates fake data on demand in a deterministic way. It is implemented as a FUSE module and can be used to test backup software.
Install Go/Golang (at least version 1.11), then run go build,
afterwards you'll find the binary in the current directory:
$ go build
$ ./fakedatafs /mnt/dir
filesystem mounted at /mnt/dir
$ ls -al /mnt/dir
total 5078
-rw-r--r-- 1 root root 15327 Aug 30 1754 file-121872730593067849
-rw-r--r-- 1 root root 89978 Aug 30 1754 file-1269644873002022781
-rw-r--r-- 1 root root 879 Aug 30 1754 file-1403895313298597120
[...]
At the moment, the only tested compiler for restic is the official Go compiler. Building restic with gccgo may work, but is not supported.