…by getting the socket path from i3 and then checking that it conforms
to what we expect. Previously we monitored /tmp, which can go wrong in
various ways, especially since i3’s directory within /tmp is not
predictable (by design).
This behavior can be avoided by passing dont_create_temp_dir => 1 to
launch_with_config (or activate_i3).
This commit fixes t/159-socketpaths.t being flaky on non-systemd computers.
With this commit, i3 will now use either $XDG_RUNTIME_DIR/i3 (XDG_RUNTIME_DIR
is only writable by the user, so this is not a problem) or a secure temporary
location in /tmp, following the pattern /tmp/i3-<user>.XXXXXX
