(tested during ntp/bullseye backport to jessie)

= Built-in test suite =

{{{
debuild
# do it again manually
make check
}}}

= smoke tests =

{{{
service ntp start
#ntpdc -c peers  # deprecated, now hangs, see #867227
ntpq -c peers
}}}

{{{
server1# service ntp start
server1# iptables -I INPUT 1 -p udp --dport 123 -j ACCEPT

server2# service ntp stop
server2# date -s now-1mn
server2# ntpdate -v server1
}}}

{{{
server1# service ntp start
server1# iptables -I INPUT 1 -p udp --dport 123 -j ACCEPT

server2# # edit /etc/ntp.conf, comment out pools, add server server1
server2# date -s now-1mn
server2# service ntp start
server2# ntpq -c peers
# be very patient
server2# date
}}}

= clknetsim =

 * https://mlichvar.fedorapeople.org/clknetsim/
 * https://github.com/mlichvar/clknetsim
 * https://github.com/mlichvar/ntptestsuite

Fix `Makefile`: `/usr/include/sys/time.h` -> `/usr/include/x86_64-linux-gnu/sys/time.h`.

{{{
cd ntclknetsim/
make
cd ntptestsuite/
PATH=/usr/sbin:$PATH ./testall.sh
}}}

Tests appear flacky but can trigger segfaults. Mostly works for jessie's ntp, but completely fails for buster & up.