Restructure devtest's unittests and run them in CI (#11859)

util/test_multiplayer.sh

@@ -20,7 +20,7 @@ waitfor () {
 }
 
 gdbrun () {
-	gdb -q -ex 'set confirm off' -ex 'r' -ex 'bt' -ex 'quit' --args "$@"
+	gdb -q -batch -ex 'set confirm off' -ex 'r' -ex 'bt' --args "$@"
 }
 
 [ -e $minetest ] || { echo "executable $minetest missing"; exit 1; }
@@ -33,17 +33,27 @@ printf '%s\n' >$testspath/client1.conf \
 	enable_{sound,minimap,shaders}=false
 
 printf '%s\n' >$testspath/server.conf \
-	max_block_send_distance=1
+	max_block_send_distance=1 devtest_unittests_autostart=true
 
 cat >$worldpath/worldmods/test/init.lua <<"LUA"
 core.after(0, function()
 	io.close(io.open(core.get_worldpath() .. "/startup", "w"))
 end)
-core.register_on_joinplayer(function(player)
-	io.close(io.open(core.get_worldpath() .. "/player_joined", "w"))
+local function callback(test_ok)
+	if not test_ok then
+		io.close(io.open(core.get_worldpath() .. "/test_failure", "w"))
+	end
+	io.close(io.open(core.get_worldpath() .. "/done", "w"))
 	core.request_shutdown("", false, 2)
-end)
+end
+if core.settings:get_bool("devtest_unittests_autostart") then
+	unittests.on_finished = callback
+else
+	core.register_on_joinplayer(function() callback(true) end)
+end
 LUA
+printf '%s\n' >$worldpath/worldmods/test/mod.conf \
+	name=test optional_depends=unittests
 
 echo "Starting server"
 gdbrun $minetest --server --config $conf_server --world $worldpath --gameid $gameid 2>&1 | sed -u 's/^/(server) /' &
@@ -51,10 +61,14 @@ waitfor $worldpath/startup
 
 echo "Starting client"
 gdbrun $minetest --config $conf_client1 --go --address 127.0.0.1 2>&1 | sed -u 's/^/(client) /' &
-waitfor $worldpath/player_joined
+waitfor $worldpath/done
 
 echo "Waiting for client and server to exit"
 wait
 
+if [ -f $worldpath/test_failure ]; then
+	echo "There were test failures."
+	exit 1
+fi
 echo "Success"
 exit 0