Add Docker test workflow

.github/workflows/test.yml

@@ -0,0 +1,12 @@
+name: "Integration test"
+on: [push, pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: docker
+      run: ./test/run.sh

mods/default/init.lua

@@ -1654,3 +1654,6 @@ dofile(modpath .. "/furnace.lua")
 dofile(modpath .. "/sao.lua")
 dofile(modpath .. "/mapgen_setup.lua")
 dofile(modpath .. "/abm.lua")
+if minetest.settings:get_bool("minetest_classic_internal_test") then
+	dofile(modpath .. "/test.lua")
+end

mods/default/test.lua

@@ -0,0 +1,38 @@
+local function wait_map(callback)
+	local pos = vector.new(5, 30, 5)
+	for y = 0, 4 do
+		assert(minetest.forceload_block(
+			vector.new(pos.x, y*16, pos.z), true, -1
+		))
+	end
+
+	local function check()
+		if minetest.get_node(pos).name ~= "ignore" then
+			return callback(pos)
+		end
+		minetest.after(0, check)
+	end
+	check()
+end
+
+
+minetest.after(0, function()
+	wait_map(function(pos)
+		for x = -1, 1 do
+		for z = -1, 1 do
+			minetest.add_node(pos:offset(x, 0, z), {name="default:dirt"})
+		end
+		end
+
+		pos = pos:offset(0, 1, 0)
+		minetest.add_entity(pos, "default:rat")
+		minetest.add_entity(pos, "default:oerkki1")
+		minetest.add_entity(pos, "default:firefly")
+		default.spawn_mobv2(pos, default.get_mob_dungeon_master())
+
+		minetest.after(2.5, function()
+			minetest.request_shutdown()
+		end)
+	end)
+end)
+

test/minetest.conf

@@ -0,0 +1,3 @@
+mg_name = v6
+minetest_classic_internal_test = true
+max_forceloaded_blocks = 500

test/run.sh

@@ -0,0 +1,15 @@
+#!/bin/bash -e
+
+[ -f game.conf ] || { echo "Must be run in game root folder." >&2; exit 1; }
+
+[ -z "$DOCKER_IMAGE" ] && DOCKER_IMAGE="ghcr.io/minetest/minetest:master"
+docker run --rm -i \
+	-v "$PWD/test/minetest.conf":/etc/minetest/minetest.conf \
+	--tmpfs /root/.minetest \
+	-v "$PWD":/root/.minetest/games/minetest_classic \
+	-v "$PWD/test/world.mt":/root/.minetest/world/world.mt \
+	-u 0:0 "$DOCKER_IMAGE"
+# -u 0:0 is needed here because MT's image defaults to an unprivileged user
+# but all of our mounts are created as root...
+
+exit 0

test/world.mt

@@ -0,0 +1,3 @@
+enable_damage = true
+creative_mode = false
+gameid = minetest_classic