harness: the oracle calls each item's own useOn

The oracle builds a stand-in level holding the case's block, hands the real
useOn a player with an empty hand and records the sound the level is asked
for; the probe reads the case's item and asks the matching branch for the
sound and the pitch.

crates/horizon-client/examples/probe/fire_starter_sound_probe.rs

@@ -1,6 +1,6 @@
 #![forbid(unsafe_code)]
-//! Runs tools/test_fire_starter_sound_parity.py's level random seeds through
-//! the fire charge's use sound (`horizon_client::items::fire_starter_pitch`).
+//! Runs tools/test_fire_starter_sound_parity.py's cases through the fire
+//! starter's use sound (`horizon_client::items::fire_starter_pitch`).
 use horizon_client::{
     Result,
     items::{fire_starter_pitch, fire_starter_sound},
@@ -16,12 +16,16 @@ pub fn main() -> Result<()> {
     let input = BufReader::new(File::open(&args[1])?);
     let mut out = BufWriter::new(File::create(&args[2])?);
     for line in input.lines() {
-        let mut random = LegacyRandom::new(line?.trim().parse()?);
-        let pitch = fire_starter_pitch(true, &mut random);
+        let line = line?;
+        let mut parts = line.trim().split(' ');
+        let fire_charge = parts.next() == Some("fire_charge");
+        parts.next(); // the block the use is made on: the sound does not read it
+        let mut random = LegacyRandom::new(parts.next().unwrap_or_default().parse()?);
+        let pitch = fire_starter_pitch(fire_charge, &mut random);
         writeln!(
             out,
             "{} {} {} {}",
-            fire_starter_sound(true),
+            fire_starter_sound(fire_charge),
             1.0f32.to_bits() as i32,
             pitch.to_bits() as i32,
             random.next_long()

mods/horizon/src/test/java/dev/horizonlab/parity/VanillaFireStarterSoundOracle.java

@@ -5,34 +5,66 @@ import java.lang.reflect.*;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.*;
 import java.util.*;
+import net.minecraft.client.player.LocalPlayer;
 import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.core.Holder;
 import net.minecraft.server.level.ServerLevel;
 import net.minecraft.util.RandomSource;
-import net.minecraft.world.item.FireChargeItem;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.entity.player.Input;
+import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.item.Items;
+import net.minecraft.world.item.context.UseOnContext;
 import net.minecraft.world.level.Level;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.block.state.properties.BlockStateProperties;
+import net.minecraft.world.level.gameevent.GameEvent;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
 
 /**
- * Original oracle for the fire charge's use sound: the real private
- * FireChargeItem.playSound (used for both a lit campfire or candle and a
- * placed fire) on a level stand-in whose random is seeded from the case,
+ * Original oracle for a fire starter's use sound: the real
+ * FireChargeItem.useOn and FlintAndSteelItem.useOn on a campfire, a candle and
+ * a stone block, on a level stand-in whose random is seeded from the case,
  * recording the sound, its volume and pitch and the level random's next long
  * (which shows how many values the sound drew).
  */
 public final class VanillaFireStarterSoundOracle {
     static final StringBuilder sounds = new StringBuilder();
+    static final BlockPos POS = new BlockPos(3, 64, -7);
 
     static final class World extends ServerLevel {
+        BlockState state = Blocks.AIR.defaultBlockState();
         World() {
             super(null, null, null, null, null, null, false, 0L, List.of(), false);
         }
+        @Override public BlockState getBlockState(BlockPos p) {
+            return p.equals(POS) ? state : Blocks.AIR.defaultBlockState();
+        }
+        @Override public boolean setBlock(BlockPos p, BlockState s, int flags) { state = s; return true; }
+        @Override public boolean setBlockAndUpdate(BlockPos p, BlockState s) { state = s; return true; }
+        @Override public void gameEvent(Entity entity, Holder<GameEvent> event, BlockPos p) {}
         @Override public void playSeededSound(net.minecraft.world.entity.Entity p, double x, double y, double z,
-                net.minecraft.core.Holder<net.minecraft.sounds.SoundEvent> s, net.minecraft.sounds.SoundSource c, float v, float pitch, long seed) {
+                Holder<net.minecraft.sounds.SoundEvent> s, net.minecraft.sounds.SoundSource c, float v, float pitch, long seed) {
             sounds.append(s.unwrapKey().orElseThrow().identifier()).append(' ')
                 .append(Float.floatToIntBits(v)).append(' ').append(Float.floatToIntBits(pitch));
         }
     }
 
+    /** The player a use is made by: only its level and its empty hand are read. */
+    static final class Shell extends LocalPlayer {
+        Shell() {
+            super(null, null, null, null, null, Input.EMPTY, false, null, null);
+        }
+        @Override public ItemStack getMainHandItem() { return ItemStack.EMPTY; }
+        @Override public ItemStack getItemBySlot(EquipmentSlot slot) { return ItemStack.EMPTY; }
+        @Override public boolean hasInfiniteMaterials() { return false; }
+    }
+
     static void put(Object unsafe, Object target, String name, Object value) throws Exception {
         Field f = Level.class.getDeclaredField(name);
         long offset = (long) unsafe.getClass().getMethod("objectFieldOffset", Field.class).invoke(unsafe, f);
@@ -46,18 +78,27 @@ public final class VanillaFireStarterSoundOracle {
         theUnsafe.setAccessible(true);
         Object unsafe = theUnsafe.get(null);
         World world = (World) u.getMethod("allocateInstance", Class.class).invoke(unsafe, World.class);
-        Method play = FireChargeItem.class.getDeclaredMethod("playSound", Level.class, BlockPos.class);
-        play.setAccessible(true);
-        var item = (FireChargeItem) Items.FIRE_CHARGE;
+        Object shell = u.getMethod("allocateInstance", Class.class).invoke(unsafe, Shell.class);
+        Field levelField = Entity.class.getDeclaredField("level");
+        levelField.setAccessible(true);
+        levelField.set(shell, world);
+        var hit = new BlockHitResult(new Vec3(3.5, 65.0, -6.5), Direction.UP, POS, false);
         try (var out = new PrintWriter(Files.newBufferedWriter(Path.of(args[1]), StandardCharsets.UTF_8));
              var lines = Files.lines(Path.of(args[0]))) {
             for (var line : (Iterable<String>) lines::iterator) {
-                long seed = Long.parseLong(line.trim());
-                RandomSource random = RandomSource.create(seed);
+                var parts = line.trim().split(" ");
+                boolean fireCharge = parts[0].equals("fire_charge");
+                world.state = switch (parts[1]) {
+                    case "campfire" -> Blocks.CAMPFIRE.defaultBlockState().setValue(BlockStateProperties.LIT, false);
+                    case "candle" -> Blocks.CANDLE.defaultBlockState().setValue(BlockStateProperties.LIT, false);
+                    default -> Blocks.STONE.defaultBlockState();
+                };
+                RandomSource random = RandomSource.create(Long.parseLong(parts[2]));
                 put(unsafe, world, "random", random);
                 put(unsafe, world, "soundSeedGenerator", RandomSource.create(0));
                 sounds.setLength(0);
-                play.invoke(item, world, new BlockPos(3, 64, -7));
+                var context = new UseOnContext((net.minecraft.world.entity.player.Player) shell, InteractionHand.MAIN_HAND, hit);
+                (fireCharge ? Items.FIRE_CHARGE : Items.FLINT_AND_STEEL).useOn(context);
                 out.println(sounds + " " + random.nextLong());
             }
         }

tools/test_fire_starter_sound_parity.py

@@ -25,9 +25,11 @@ def make_cases(build):
 
 
 def main():
-    scope = ('The real private FireChargeItem.playSound on a ServerLevel stand-in with a seeded LegacyRandomSource: '
-             'the sound event, volume, pitch ((nextFloat - nextFloat) * 0.2 + 1) and the random afterwards. '
-             'FireChargeItem.useOn\'s choice between lighting and placing fire is not exercised.')
+    scope = ('Real FireChargeItem.useOn and FlintAndSteelItem.useOn on a ServerLevel stand-in holding a campfire, a '
+             'candle or stone, with a seeded LegacyRandomSource: the sound event, volume, pitch ((nextFloat - nextFloat) '
+             '* 0.2 + 1 for the charge, nextFloat * 0.4 + 0.8 for the steel) and the random afterwards. Both items light '
+             'a campfire and a candle and place fire on stone; the block states they write, their game events and the '
+             'item damage are not compared.')
     harness.differential(
         'rust-fire-starter-sound-parity', 'VanillaFireStarterSoundOracle', 'fire_starter_sound_probe', make_cases,
         scope, sources=[lab.ROOT / 'crates/horizon-items/src/items.rs'])