test(sync): cover registered block and item sync paths

src/test/java/com/modularmc/synceddata/test/SyncAnnotationTest.java

@@ -2,6 +2,7 @@
 
 import com.modularmc.synceddata.api.sync_system.meta.ClassSyncData;
 
+import net.minecraft.core.BlockPos;
 import net.minecraft.gametest.framework.GameTestHelper;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.item.Items;
@@ -160,4 +161,52 @@ public static void item(GameTestHelper helper) {
         check(helper, restored.e == 500, "item rt");
         helper.succeed();
     }
+
+    @TestHolder(value = "sync_registered_block_entity")
+    @EmptyTemplate("3")
+    @GameTest
+    public static void registeredBlockEntity(GameTestHelper helper) {
+        helper.setBlock(1, 1, 1, SyncedTestContent.TEST_SYNC_BLOCK.get());
+        var blockEntity = helper.getBlockEntity(new BlockPos(1, 1, 1), SyncTestFixtures.TestManagedBlockEntity.class);
+        blockEntity.energy = 240;
+        blockEntity.config = "gt";
+        blockEntity.target = 9;
+
+        var saveTag = blockEntity.getSyncDataHolder().serializeToSaveNBT(helper.getLevel().registryAccess());
+        check(helper, saveTag.getInt("energy").orElse(0) == 240, "energy save missing");
+
+        byte[] serverChanges = blockEntity.getSyncDataHolder().collectServerNetworkChanges(helper.getLevel().registryAccess());
+        check(helper, serverChanges.length > 0, "server network payload missing");
+
+        var restored = new SyncTestFixtures.TestManagedBlockEntity();
+        restored.getSyncDataHolder().applyServerNetworkUpdate(helper.getLevel().registryAccess(), serverChanges);
+        check(helper, restored.target == 9, "registered block entity target not restored");
+        helper.succeed();
+    }
+
+    @TestHolder(value = "sync_registered_block_item")
+    @EmptyTemplate("3")
+    @GameTest
+    public static void registeredBlockItem(GameTestHelper helper) {
+        helper.setBlock(1, 1, 1, SyncedTestContent.TEST_SYNC_BLOCK.get());
+        var blockEntity = helper.getBlockEntity(new BlockPos(1, 1, 1), SyncTestFixtures.TestManagedBlockEntity.class);
+        blockEntity.energy = 512;
+        blockEntity.config = "item-data";
+        blockEntity.target = 33;
+
+        ItemStack stack = SyncedTestContent.TEST_SYNC_BLOCK_ITEM.toStack();
+        var components = blockEntity.collectItemComponentsForTest();
+        stack.applyComponents(components);
+
+        helper.setBlock(2, 1, 1, SyncedTestContent.TEST_SYNC_BLOCK.get());
+        var restored = helper.getBlockEntity(new BlockPos(2, 1, 1), SyncTestFixtures.TestManagedBlockEntity.class);
+        restored.applyItemComponentsForTest(stack.getComponents());
+        check(helper, restored.config.equals("item-data"), "block item config not restored");
+        check(helper, restored.target == 0, "block item should not restore sync-only field");
+        check(helper, restored.energy == 0, "block item should not restore save-only field");
+
+        restored.getSyncDataHolder().loadFromItemStack(stack, helper.getLevel().registryAccess());
+        check(helper, restored.config.equals("item-data"), "loadFromItemStack config not restored");
+        helper.succeed();
+    }
 }

src/test/java/com/modularmc/synceddata/test/SyncTestFixtures.java

@@ -1,6 +1,8 @@
 package com.modularmc.synceddata.test;
 
+import com.modularmc.synceddata.api.blockentity.BlockEntityCreationInfo;
 import com.modularmc.synceddata.api.sync_system.ISyncManaged;
+import com.modularmc.synceddata.api.sync_system.ManagedSyncBlockEntity;
 import com.modularmc.synceddata.api.sync_system.annotations.ClientFieldChangeListener;
 import com.modularmc.synceddata.api.sync_system.annotations.ItemSave;
 import com.modularmc.synceddata.api.sync_system.annotations.RerenderOnChanged;
@@ -11,6 +13,9 @@
 import com.modularmc.synceddata.api.sync_system.holder.SyncDataHolder;
 import com.modularmc.synceddata.api.sync_system.meta.FieldCodecs;
 
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.component.DataComponentGetter;
+import net.minecraft.core.component.DataComponentMap;
 import net.minecraft.gametest.framework.GameTestHelper;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.nbt.NbtOps;
@@ -177,6 +182,44 @@ void onTarget() {
         }
     }
 
+    static final class TestManagedBlockEntity extends ManagedSyncBlockEntity {
+
+        @SaveField
+        int energy;
+        @ItemSave
+        String config;
+        @SyncBoth
+        int target;
+        final List<String> callbacks = new ArrayList<>();
+
+        TestManagedBlockEntity(BlockPos pos, net.minecraft.world.level.block.state.BlockState state) {
+            super(SyncedTestContent.TEST_SYNC_BLOCK_ENTITY.get(), pos, state);
+        }
+
+        TestManagedBlockEntity() {
+            super(new BlockEntityCreationInfo(SyncedTestContent.TEST_SYNC_BLOCK_ENTITY.get(), BlockPos.ZERO,
+                    SyncedTestContent.TEST_SYNC_BLOCK.get().defaultBlockState()));
+        }
+
+        @ClientFieldChangeListener(fieldName = "target")
+        void onTargetChanged() {
+            callbacks.add("target");
+        }
+
+        @Override
+        public void scheduleRenderUpdate() {}
+
+        DataComponentMap collectItemComponentsForTest() {
+            DataComponentMap.Builder builder = DataComponentMap.builder();
+            collectImplicitComponents(builder);
+            return builder.build();
+        }
+
+        void applyItemComponentsForTest(DataComponentGetter components) {
+            applyImplicitComponents(components);
+        }
+    }
+
     static class TestItemData implements ISyncManaged {
 
         final ItemSyncHolder itemSyncHolder = new ItemSyncHolder(this);

src/test/java/com/modularmc/synceddata/test/SyncedTestContent.java

@@ -0,0 +1,62 @@
+package com.modularmc.synceddata.test;
+
+import com.modularmc.synceddata.SyncedData;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.level.block.BaseEntityBlock;
+import net.minecraft.world.level.block.RenderShape;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.entity.BlockEntityType;
+import net.minecraft.world.level.block.state.BlockBehaviour;
+import net.minecraft.world.level.block.state.BlockState;
+import net.neoforged.bus.api.IEventBus;
+import net.neoforged.neoforge.registries.DeferredBlock;
+import net.neoforged.neoforge.registries.DeferredHolder;
+import net.neoforged.neoforge.registries.DeferredItem;
+import net.neoforged.neoforge.registries.DeferredRegister;
+
+import com.mojang.serialization.MapCodec;
+
+public final class SyncedTestContent {
+
+    public static final DeferredRegister.Blocks BLOCKS = DeferredRegister.createBlocks(SyncedData.MOD_ID);
+    public static final DeferredRegister.Items ITEMS = DeferredRegister.createItems(SyncedData.MOD_ID);
+    public static final DeferredRegister<BlockEntityType<?>> BLOCK_ENTITY_TYPES = DeferredRegister.create(net.minecraft.core.registries.Registries.BLOCK_ENTITY_TYPE, SyncedData.MOD_ID);
+
+    public static final DeferredBlock<TestSyncBlock> TEST_SYNC_BLOCK = BLOCKS.registerBlock("test_sync_block", TestSyncBlock::new, properties -> properties.strength(1.5F));
+    public static final DeferredItem<net.minecraft.world.item.BlockItem> TEST_SYNC_BLOCK_ITEM = ITEMS.registerSimpleBlockItem("test_sync_block", TEST_SYNC_BLOCK);
+    public static final DeferredHolder<BlockEntityType<?>, BlockEntityType<SyncTestFixtures.TestManagedBlockEntity>> TEST_SYNC_BLOCK_ENTITY = BLOCK_ENTITY_TYPES.register("test_sync_block_entity",
+            () -> new BlockEntityType<>(SyncTestFixtures.TestManagedBlockEntity::new, TEST_SYNC_BLOCK.get()));
+
+    private SyncedTestContent() {}
+
+    public static void register(IEventBus bus) {
+        BLOCKS.register(bus);
+        ITEMS.register(bus);
+        BLOCK_ENTITY_TYPES.register(bus);
+    }
+
+    public static final class TestSyncBlock extends BaseEntityBlock {
+
+        public static final MapCodec<TestSyncBlock> CODEC = simpleCodec(TestSyncBlock::new);
+
+        public TestSyncBlock(BlockBehaviour.Properties properties) {
+            super(properties);
+        }
+
+        @Override
+        protected MapCodec<? extends BaseEntityBlock> codec() {
+            return CODEC;
+        }
+
+        @Override
+        protected RenderShape getRenderShape(BlockState state) {
+            return RenderShape.MODEL;
+        }
+
+        @Override
+        public BlockEntity newBlockEntity(BlockPos pos, BlockState state) {
+            return new SyncTestFixtures.TestManagedBlockEntity(pos, state);
+        }
+    }
+}

src/test/java/com/modularmc/synceddata/test/SyncedTestFramework.java

@@ -11,6 +11,7 @@
 public final class SyncedTestFramework {
 
     public SyncedTestFramework(IEventBus bus, ModContainer container) {
+        SyncedTestContent.register(bus);
         FrameworkConfiguration.builder(SyncedData.id("tests"))
                 .build()
                 .create()