Only load resources once for gametest servers

patches/net/minecraft/server/Main.java.patch

@@ -85,6 +85,22 @@
                      } catch (NbtException | ReportedNbtException | IOException ioexception) {
                          LOGGER.error("Failed to load world data from {}", levelstoragesource$leveldirectory.oldDataFile(), ioexception);
                          LOGGER.error(
+@@ -173,6 +_,15 @@
+
+             PackRepository packrepository = ServerPacksSource.createPackRepository(levelstoragesource$levelstorageaccess);
+
++            if (gametestEnabled) {
++                net.neoforged.neoforge.gametest.GameTestHooks.registerGametests();
++                net.minecraft.core.BlockPos spawnPos = optionset.valueOf(spawnPosOpt);
++                MinecraftServer.spin(thread -> net.minecraft.gametest.framework.GameTestServer.create(thread, levelstoragesource$levelstorageaccess, packrepository, net.minecraft.gametest.framework.GameTestRegistry.getAllTestFunctions(), spawnPos));
++                // If we're running a gametest server we don't need to load the resources normally (GameTestServer#create does it using a flat world)
++                // or create a shutdown thread as the gametest server will always exit itself
++                return;
++            }
++
+             WorldStem worldstem;
+             try {
+                 WorldLoader.InitConfig worldloader$initconfig = loadOrCreateConfig(dedicatedserversettings.getProperties(), dynamic1, flag, packrepository);
 @@ -214,6 +_,9 @@
                                              worlddimensions = dedicatedserverproperties.createDimensions(p_307161_.datapackWorldgen());
                                          }
@@ -95,48 +111,9 @@
                                          WorldDimensions.Complete worlddimensions$complete = worlddimensions.bake(registry);
                                          Lifecycle lifecycle = worlddimensions$complete.lifecycle().add(p_307161_.datapackWorldgen().allRegistriesLifecycle());
                                          return new WorldLoader.DataLoadOutput<>(
-@@ -246,24 +_,22 @@
-
-             WorldData worlddata = worldstem.worldData();
-             levelstoragesource$levelstorageaccess.saveDataTag(registryaccess$frozen, worlddata);
--            final DedicatedServer dedicatedserver = MinecraftServer.spin(
-+            final MinecraftServer dedicatedserver = MinecraftServer.spin(
-                 p_293760_ -> {
--                    DedicatedServer dedicatedserver1 = new DedicatedServer(
--                        p_293760_,
--                        levelstoragesource$levelstorageaccess,
--                        packrepository,
--                        worldstem,
--                        dedicatedserversettings,
--                        DataFixers.getDataFixer(),
--                        services,
--                        LoggerChunkProgressListener::createFromGameruleRadius
--                    );
-+                    MinecraftServer dedicatedserver1;
-+                    if (gametestEnabled) {
-+                        net.neoforged.neoforge.gametest.GameTestHooks.registerGametests();
-+                        net.minecraft.core.BlockPos spawnPos = optionset.valueOf(spawnPosOpt);
-+                        dedicatedserver1 = net.minecraft.gametest.framework.GameTestServer.create(p_293760_, levelstoragesource$levelstorageaccess, packrepository, net.minecraft.gametest.framework.GameTestRegistry.getAllTestFunctions(), spawnPos);
-+                    } else {
-+                        dedicatedserver1 = new DedicatedServer(p_293760_, levelstoragesource$levelstorageaccess, packrepository, worldstem, dedicatedserversettings, DataFixers.getDataFixer(), services, LoggerChunkProgressListener::createFromGameruleRadius);
-+                    }
-                     dedicatedserver1.setPort(optionset.valueOf(optionspec11));
-                     dedicatedserver1.setDemo(optionset.has(optionspec2));
-                     dedicatedserver1.setId(optionset.valueOf(optionspec12));
-                     boolean flag2 = !optionset.has(optionspec) && !optionset.valuesOf(optionspec15).contains("nogui");
--                    if (flag2 && !GraphicsEnvironment.isHeadless()) {
--                        dedicatedserver1.showGui();
-+                    if (dedicatedserver1 instanceof DedicatedServer dedicatedServer && flag2 && !GraphicsEnvironment.isHeadless()) {
-+                        dedicatedServer.showGui();
-                     }
-
-                     return dedicatedserver1;
-@@ -272,7 +_,10 @@
-             Thread thread = new Thread("Server Shutdown Thread") {
+@@ -273,6 +_,7 @@
                  @Override
                  public void run() {
-+                    // FORGE: Halting as GameTestServer will cause issues as it always calls System#exit on both crash and normal exit, so skip it
-+                    if (!(dedicatedserver instanceof net.minecraft.gametest.framework.GameTestServer))
                      dedicatedserver.halt(true);
 +                    org.apache.logging.log4j.LogManager.shutdown(); // we're manually managing the logging shutdown on the server. Make sure we do it here at the end.
                  }

tests/src/generated/resources/data/neotests_reloadable_reg_data_maps/data_maps/loot_table/effect_grant.json

@@ -0,0 +1,13 @@
+{
+  "values": {
+    "minecraft:blocks/copper_block": {
+      "duration": 100,
+      "id": "minecraft:nausea",
+      "neoforge:cures": [
+        "protected_by_totem",
+        "milk"
+      ],
+      "show_icon": true
+    }
+  }
+}

tests/src/main/java/net/neoforged/neoforge/debug/data/DataMapTests.java

@@ -32,6 +32,8 @@
 import net.minecraft.world.InteractionHand;
 import net.minecraft.world.damagesource.DamageType;
 import net.minecraft.world.damagesource.DamageTypes;
+import net.minecraft.world.effect.MobEffectInstance;
+import net.minecraft.world.effect.MobEffects;
 import net.minecraft.world.entity.player.Player;
 import net.minecraft.world.item.HoneycombItem;
 import net.minecraft.world.item.Item;
@@ -42,12 +44,14 @@
 import net.minecraft.world.level.block.WeatheringCopper;
 import net.minecraft.world.level.block.WeatheringCopperFullBlock;
 import net.minecraft.world.level.block.state.BlockBehaviour;
+import net.minecraft.world.level.storage.loot.LootTable;
 import net.neoforged.neoforge.common.DataMapHooks;
 import net.neoforged.neoforge.common.NeoForge;
 import net.neoforged.neoforge.common.data.DataMapProvider;
 import net.neoforged.neoforge.debug.EventTests;
 import net.neoforged.neoforge.event.entity.living.LivingDamageEvent;
 import net.neoforged.neoforge.event.entity.player.UseItemOnBlockEvent;
+import net.neoforged.neoforge.event.level.BlockEvent;
 import net.neoforged.neoforge.registries.datamaps.AdvancedDataMapType;
 import net.neoforged.neoforge.registries.datamaps.DataMapType;
 import net.neoforged.neoforge.registries.datamaps.DataMapValueMerger;
@@ -301,6 +305,38 @@ protected void gather() {
         });
     }
 
+    @GameTest
+    @EmptyTemplate
+    @TestHolder(description = "Tests if data maps can be successfully attached to reloadable registries")
+    static void reloadableRegDataMaps(final DynamicTest test, final RegistrationHelper reg) {
+        final DataMapType<LootTable, MobEffectInstance> effectGrant = reg.registerDataMap(DataMapType.builder(
+                ResourceLocation.fromNamespaceAndPath(reg.modId(), "effect_grant"),
+                Registries.LOOT_TABLE, MobEffectInstance.CODEC)
+                .build());
+
+        reg.addProvider(event -> new DataMapProvider(event.getGenerator().getPackOutput(), event.getLookupProvider()) {
+            @Override
+            protected void gather() {
+                builder(effectGrant)
+                        .add(Blocks.COPPER_BLOCK.getLootTable(), new MobEffectInstance(MobEffects.CONFUSION, 100), false);
+            }
+        });
+
+        test.eventListeners().forge().addListener((final BlockEvent.EntityPlaceEvent event) -> {
+            final var grant = event.getLevel().getServer().reloadableRegistries().lookup().lookupOrThrow(Registries.LOOT_TABLE).getOrThrow(event.getPlacedBlock().getBlock().getLootTable()).getData(effectGrant);
+            if (grant != null && event.getEntity() instanceof Player player) {
+                player.addEffect(grant);
+            }
+        });
+
+        test.onGameTest(helper -> {
+            final Player player = helper.makeMockPlayer();
+            helper.useBlock(new BlockPos(0, 1, 0), player, Blocks.COPPER_BLOCK.asItem().getDefaultInstance());
+            helper.assertMobEffectPresent(player, MobEffects.CONFUSION, "has confusion");
+            helper.succeed();
+        });
+    }
+
     @GameTest
     @EmptyTemplate
     @TestHolder(description = "Tests if custom compostables work")