Add a test for exploding turtles

There's been a couple of bug reports in the past where the game would
crash if a turtle is destroyed while breaking a block (typically due to
the block exploding). This commit adds a test, to ensure that this is
handled gracefully.

I'm not entirely sure this is testing the right thing. Looking at the
issues in question, it doesn't look like I ever managed to reproduce the
bug. However, it's hopefully at least a quick sanity test to check we
never break this case.

projects/common/src/testMod/kotlin/dan200/computercraft/gametest/Turtle_Test.kt

@@ -693,6 +693,20 @@ class Turtle_Test {
         }
     }
 
+    /**
+     * Tests a turtle can break a block that explodes, causing the turtle itself to explode.
+     *
+     * This attempts to test [#585](https://github.com/cc-tweaked/CC-Tweaked/issues/585) and other similar issues. It's
+     * not clear if this is a good test case, as that bug does not seem reliably reproducible, but it's at least a good
+     * sanity check.
+     */
+    @GameTest
+    fun Breaks_exploding_block(context: GameTestHelper) = context.sequence {
+        thenOnComputer { turtle.dig(Optional.empty()) }
+        thenIdle(2)
+        thenExecute { context.assertItemEntityPresent(ModRegistry.Items.TURTLE_NORMAL.get(), BlockPos(2, 2, 2), 1.0) }
+    }
+
     /**
      * Render turtles as an item.
      */

projects/common/src/testMod/kotlin/dan200/computercraft/gametest/core/TestHooks.kt

@@ -13,7 +13,13 @@ import dan200.computercraft.shared.computer.core.ServerContext
 import net.minecraft.core.BlockPos
 import net.minecraft.gametest.framework.*
 import net.minecraft.server.MinecraftServer
+import net.minecraft.server.level.ServerLevel
 import net.minecraft.world.level.GameRules
+import net.minecraft.world.level.Level
+import net.minecraft.world.level.LevelAccessor
+import net.minecraft.world.level.block.Blocks
+import net.minecraft.world.level.block.state.BlockState
+import net.minecraft.world.phys.Vec3
 import org.slf4j.Logger
 import org.slf4j.LoggerFactory
 import java.io.File
@@ -173,4 +179,23 @@ object TestHooks {
             throw RuntimeException(e)
         }
     }
+
+    /**
+     * Adds a hook that makes breaking a bone block spawn an explosion.
+     *
+     * It would be more Correct to register a custom block, but that's quite a lot of work, and doesn't seem worth it
+     * for test code.
+     *
+     * See also [Turtle_Test.Breaks_exploding_block].
+     */
+    @JvmStatic
+    fun onBeforeDestroyBlock(level: LevelAccessor, pos: BlockPos, state: BlockState): Boolean {
+        if (state.block === Blocks.BONE_BLOCK && level is ServerLevel) {
+            val explosionPos = Vec3.atCenterOf(pos)
+            level.explode(null, explosionPos.x, explosionPos.y, explosionPos.z, 4.0f, Level.ExplosionInteraction.TNT)
+            return true
+        }
+
+        return false
+    }
 }

projects/common/src/testMod/resources/data/cctest/structures/turtle_test.breaks_exploding_block.snbt

@@ -0,0 +1,139 @@
+{
+    DataVersion: 3465,
+    size: [5, 5, 5],
+    data: [
+        {pos: [0, 0, 0], state: "minecraft:obsidian"},
+        {pos: [0, 0, 1], state: "minecraft:obsidian"},
+        {pos: [0, 0, 2], state: "minecraft:obsidian"},
+        {pos: [0, 0, 3], state: "minecraft:obsidian"},
+        {pos: [0, 0, 4], state: "minecraft:obsidian"},
+        {pos: [1, 0, 0], state: "minecraft:obsidian"},
+        {pos: [1, 0, 1], state: "minecraft:obsidian"},
+        {pos: [1, 0, 2], state: "minecraft:obsidian"},
+        {pos: [1, 0, 3], state: "minecraft:obsidian"},
+        {pos: [1, 0, 4], state: "minecraft:obsidian"},
+        {pos: [2, 0, 0], state: "minecraft:obsidian"},
+        {pos: [2, 0, 1], state: "minecraft:obsidian"},
+        {pos: [2, 0, 2], state: "minecraft:obsidian"},
+        {pos: [2, 0, 3], state: "minecraft:obsidian"},
+        {pos: [2, 0, 4], state: "minecraft:obsidian"},
+        {pos: [3, 0, 0], state: "minecraft:obsidian"},
+        {pos: [3, 0, 1], state: "minecraft:obsidian"},
+        {pos: [3, 0, 2], state: "minecraft:obsidian"},
+        {pos: [3, 0, 3], state: "minecraft:obsidian"},
+        {pos: [3, 0, 4], state: "minecraft:obsidian"},
+        {pos: [4, 0, 0], state: "minecraft:obsidian"},
+        {pos: [4, 0, 1], state: "minecraft:obsidian"},
+        {pos: [4, 0, 2], state: "minecraft:obsidian"},
+        {pos: [4, 0, 3], state: "minecraft:obsidian"},
+        {pos: [4, 0, 4], state: "minecraft:obsidian"},
+        {pos: [0, 1, 0], state: "minecraft:barrier"},
+        {pos: [0, 1, 1], state: "minecraft:barrier"},
+        {pos: [0, 1, 2], state: "minecraft:barrier"},
+        {pos: [0, 1, 3], state: "minecraft:barrier"},
+        {pos: [0, 1, 4], state: "minecraft:barrier"},
+        {pos: [1, 1, 0], state: "minecraft:barrier"},
+        {pos: [1, 1, 1], state: "minecraft:air"},
+        {pos: [1, 1, 2], state: "minecraft:air"},
+        {pos: [1, 1, 3], state: "minecraft:air"},
+        {pos: [1, 1, 4], state: "minecraft:barrier"},
+        {pos: [2, 1, 0], state: "minecraft:barrier"},
+        {pos: [2, 1, 1], state: "minecraft:air"},
+        {pos: [2, 1, 2], state: "computercraft:turtle_normal{facing:south,waterlogged:false}", nbt: {ComputerId: 1, Fuel: 0, Items: [], Label: "turtle_test.breaks_exploding_block", LeftUpgrade: "minecraft:diamond_pickaxe", LeftUpgradeNbt: {Tag: {Damage: 0}}, On: 1b, Owner: {LowerId: -5670393268852517359L, Name: "Player172", UpperId: 3578583684139923613L}, Slot: 0, id: "computercraft:turtle_normal"}},
+        {pos: [2, 1, 3], state: "minecraft:bone_block{axis:y}"},
+        {pos: [2, 1, 4], state: "minecraft:barrier"},
+        {pos: [3, 1, 0], state: "minecraft:barrier"},
+        {pos: [3, 1, 1], state: "minecraft:air"},
+        {pos: [3, 1, 2], state: "minecraft:air"},
+        {pos: [3, 1, 3], state: "minecraft:air"},
+        {pos: [3, 1, 4], state: "minecraft:barrier"},
+        {pos: [4, 1, 0], state: "minecraft:barrier"},
+        {pos: [4, 1, 1], state: "minecraft:barrier"},
+        {pos: [4, 1, 2], state: "minecraft:barrier"},
+        {pos: [4, 1, 3], state: "minecraft:barrier"},
+        {pos: [4, 1, 4], state: "minecraft:barrier"},
+        {pos: [0, 2, 0], state: "minecraft:barrier"},
+        {pos: [0, 2, 1], state: "minecraft:barrier"},
+        {pos: [0, 2, 2], state: "minecraft:air"},
+        {pos: [0, 2, 3], state: "minecraft:barrier"},
+        {pos: [0, 2, 4], state: "minecraft:barrier"},
+        {pos: [1, 2, 0], state: "minecraft:barrier"},
+        {pos: [1, 2, 1], state: "minecraft:air"},
+        {pos: [1, 2, 2], state: "minecraft:air"},
+        {pos: [1, 2, 3], state: "minecraft:air"},
+        {pos: [1, 2, 4], state: "minecraft:barrier"},
+        {pos: [2, 2, 0], state: "minecraft:barrier"},
+        {pos: [2, 2, 1], state: "minecraft:air"},
+        {pos: [2, 2, 2], state: "minecraft:air"},
+        {pos: [2, 2, 3], state: "minecraft:air"},
+        {pos: [2, 2, 4], state: "minecraft:barrier"},
+        {pos: [3, 2, 0], state: "minecraft:barrier"},
+        {pos: [3, 2, 1], state: "minecraft:air"},
+        {pos: [3, 2, 2], state: "minecraft:air"},
+        {pos: [3, 2, 3], state: "minecraft:air"},
+        {pos: [3, 2, 4], state: "minecraft:barrier"},
+        {pos: [4, 2, 0], state: "minecraft:barrier"},
+        {pos: [4, 2, 1], state: "minecraft:barrier"},
+        {pos: [4, 2, 2], state: "minecraft:barrier"},
+        {pos: [4, 2, 3], state: "minecraft:barrier"},
+        {pos: [4, 2, 4], state: "minecraft:barrier"},
+        {pos: [0, 3, 0], state: "minecraft:air"},
+        {pos: [0, 3, 1], state: "minecraft:air"},
+        {pos: [0, 3, 2], state: "minecraft:air"},
+        {pos: [0, 3, 3], state: "minecraft:air"},
+        {pos: [0, 3, 4], state: "minecraft:air"},
+        {pos: [1, 3, 0], state: "minecraft:air"},
+        {pos: [1, 3, 1], state: "minecraft:air"},
+        {pos: [1, 3, 2], state: "minecraft:air"},
+        {pos: [1, 3, 3], state: "minecraft:air"},
+        {pos: [1, 3, 4], state: "minecraft:air"},
+        {pos: [2, 3, 0], state: "minecraft:air"},
+        {pos: [2, 3, 1], state: "minecraft:air"},
+        {pos: [2, 3, 2], state: "minecraft:air"},
+        {pos: [2, 3, 3], state: "minecraft:air"},
+        {pos: [2, 3, 4], state: "minecraft:air"},
+        {pos: [3, 3, 0], state: "minecraft:air"},
+        {pos: [3, 3, 1], state: "minecraft:air"},
+        {pos: [3, 3, 2], state: "minecraft:air"},
+        {pos: [3, 3, 3], state: "minecraft:air"},
+        {pos: [3, 3, 4], state: "minecraft:air"},
+        {pos: [4, 3, 0], state: "minecraft:air"},
+        {pos: [4, 3, 1], state: "minecraft:air"},
+        {pos: [4, 3, 2], state: "minecraft:air"},
+        {pos: [4, 3, 3], state: "minecraft:air"},
+        {pos: [4, 3, 4], state: "minecraft:air"},
+        {pos: [0, 4, 0], state: "minecraft:air"},
+        {pos: [0, 4, 1], state: "minecraft:air"},
+        {pos: [0, 4, 2], state: "minecraft:air"},
+        {pos: [0, 4, 3], state: "minecraft:air"},
+        {pos: [0, 4, 4], state: "minecraft:air"},
+        {pos: [1, 4, 0], state: "minecraft:air"},
+        {pos: [1, 4, 1], state: "minecraft:air"},
+        {pos: [1, 4, 2], state: "minecraft:air"},
+        {pos: [1, 4, 3], state: "minecraft:air"},
+        {pos: [1, 4, 4], state: "minecraft:air"},
+        {pos: [2, 4, 0], state: "minecraft:air"},
+        {pos: [2, 4, 1], state: "minecraft:air"},
+        {pos: [2, 4, 2], state: "minecraft:air"},
+        {pos: [2, 4, 3], state: "minecraft:air"},
+        {pos: [2, 4, 4], state: "minecraft:air"},
+        {pos: [3, 4, 0], state: "minecraft:air"},
+        {pos: [3, 4, 1], state: "minecraft:air"},
+        {pos: [3, 4, 2], state: "minecraft:air"},
+        {pos: [3, 4, 3], state: "minecraft:air"},
+        {pos: [3, 4, 4], state: "minecraft:air"},
+        {pos: [4, 4, 0], state: "minecraft:air"},
+        {pos: [4, 4, 1], state: "minecraft:air"},
+        {pos: [4, 4, 2], state: "minecraft:air"},
+        {pos: [4, 4, 3], state: "minecraft:air"},
+        {pos: [4, 4, 4], state: "minecraft:air"}
+    ],
+    entities: [],
+    palette: [
+        "minecraft:obsidian",
+        "minecraft:barrier",
+        "minecraft:bone_block{axis:y}",
+        "minecraft:air",
+        "computercraft:turtle_normal{facing:south,waterlogged:false}"
+    ]
+}

projects/fabric/src/testMod/java/dan200/computercraft/gametest/core/TestMod.java

@@ -14,6 +14,7 @@ import net.fabricmc.fabric.api.command.v2.CommandRegistrationCallback;
 import net.fabricmc.fabric.api.event.Event;
 import net.fabricmc.fabric.api.event.lifecycle.v1.ServerLifecycleEvents;
 import net.fabricmc.fabric.api.event.lifecycle.v1.ServerTickEvents;
+import net.fabricmc.fabric.api.event.player.PlayerBlockBreakEvents;
 import net.minecraft.gametest.framework.GameTestRegistry;
 import net.minecraft.resources.ResourceLocation;
 
@@ -26,6 +27,7 @@ public class TestMod implements ModInitializer, ClientModInitializer {
         ServerLifecycleEvents.SERVER_STARTED.addPhaseOrdering(Event.DEFAULT_PHASE, phase);
         ServerLifecycleEvents.SERVER_STARTED.register(phase, TestHooks::onServerStarted);
         CommandRegistrationCallback.EVENT.register((dispatcher, registryAccess, environment) -> CCTestCommand.register(dispatcher));
+        PlayerBlockBreakEvents.BEFORE.register((level, player, pos, state, blockEntity) -> !TestHooks.onBeforeDestroyBlock(level, pos, state));
 
         TestHooks.loadTests(GameTestRegistry::register);
     }

projects/forge/src/testMod/java/dan200/computercraft/gametest/core/TestMod.java

@@ -12,6 +12,7 @@ import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.event.RegisterCommandsEvent;
 import net.minecraftforge.event.RegisterGameTestsEvent;
 import net.minecraftforge.event.TickEvent;
+import net.minecraftforge.event.level.BlockEvent;
 import net.minecraftforge.event.server.ServerStartedEvent;
 import net.minecraftforge.eventbus.api.EventPriority;
 import net.minecraftforge.fml.DistExecutor;
@@ -26,6 +27,10 @@ public class TestMod {
         var bus = MinecraftForge.EVENT_BUS;
         bus.addListener(EventPriority.LOW, (ServerStartedEvent e) -> TestHooks.onServerStarted(e.getServer()));
         bus.addListener((RegisterCommandsEvent e) -> CCTestCommand.register(e.getDispatcher()));
+        bus.addListener((BlockEvent.BreakEvent e) -> {
+            if (TestHooks.onBeforeDestroyBlock(e.getLevel(), e.getPos(), e.getState())) e.setCanceled(true);
+        });
+
         DistExecutor.unsafeRunWhenOn(Dist.CLIENT, () -> TestMod::onInitializeClient);
 
         var modBus = FMLJavaModLoadingContext.get().getModEventBus();