Trivial:
$ mkdir /tftproot
$ cd /tftproot
$ vim testfile
$ tftp localhost
tftp> get testfile
Normal:
$ cd /usr/tests/libexec/tftpd
$ kyua test -k Kyuafile
one case testing
$ kyua debug -k Kyuafile functional:testcase
Set up enotcapable to get coredump
sysctl kern.trap_enotcap=1
sysctl kern.corefile= /tmp/coredumps/%N.core
gdb executable corefile