This patch updates the shell scripts with some of the common best
practices, which should make them more resilient to unusual failures and
unexpected environments (in particular, directories with spaces).
Most of these were identified by shellcheck.
Most integration tests depend on the $HOSTALIASES environment variable
being functional. That variable works on most systems, but not all. In
particular, systems with `systemd-resolved` can cause the variable to be
ignored.
This was reported by Alex Ellwein in
https://github.com/albertito/chasquid/issues/20.
This patch makes the affected tests to be skipped if $HOSTALIASES is not
working properly. It also removes unnecessary hosts files from tests
which don't need it, and documents this behaviour.
Thanks to Alex Ellwein and foxcpp@ for reporting and helping investigate
this issue!
This patch introduces stress tests, which put load on the daemon to help
sanity check its behaviour under stress.
They are separate from the existing integration tests, which focus on
correctness.
Two tests are included here: a load test, which sends emails repeatedly;
and a connection test which opens as many conections as possible.
