path: root/patches/server/0905-Add-drops-to-shear-events.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Tue, 18 May 2021 12:32:02 -0700
Subject: [PATCH] Add drops to shear events


diff --git a/src/main/java/net/minecraft/core/dispenser/ShearsDispenseItemBehavior.java b/src/main/java/net/minecraft/core/dispenser/ShearsDispenseItemBehavior.java
index 9b5a1dc958232e4c2c9631f3504edc6383afd92a..f5206e4176f58cff4cfe70c94f014afebc98c589 100644
--- a/src/main/java/net/minecraft/core/dispenser/ShearsDispenseItemBehavior.java
+++ b/src/main/java/net/minecraft/core/dispenser/ShearsDispenseItemBehavior.java
@@ -103,11 +103,14 @@ public class ShearsDispenseItemBehavior extends OptionalDispenseItemBehavior {
             if (entityliving instanceof Shearable ishearable) {
                 if (ishearable.readyForShearing()) {
                     // CraftBukkit start
-                    if (CraftEventFactory.callBlockShearEntityEvent(entityliving, bukkitBlock, craftItem).isCancelled()) {
+                    // Paper start - Add drops to shear events
+                    org.bukkit.event.block.BlockShearEntityEvent event = CraftEventFactory.callBlockShearEntityEvent(entityliving, bukkitBlock, craftItem, ishearable.generateDefaultDrops(worldserver, itemstack));
+                    if (event.isCancelled()) {
+                        // Paper end - Add drops to shear events
                         continue;
                     }
                     // CraftBukkit end
-                    ishearable.shear(worldserver, SoundSource.BLOCKS, itemstack);
+                    ishearable.shear(worldserver, SoundSource.BLOCKS, itemstack, CraftItemStack.asNMSCopy(event.getDrops())); // Paper - Add drops to shear events
                     worldserver.gameEvent((Entity) null, (Holder) GameEvent.SHEAR, blockposition);
                     return true;
                 }
diff --git a/src/main/java/net/minecraft/world/entity/Shearable.java b/src/main/java/net/minecraft/world/entity/Shearable.java
index 35076593f3ccd651295ae1fc9bcf8256c19672dd..8fda407c9fbfdde623564a7d9607275c4894b744 100644
--- a/src/main/java/net/minecraft/world/entity/Shearable.java
+++ b/src/main/java/net/minecraft/world/entity/Shearable.java
@@ -5,8 +5,15 @@ import net.minecraft.sounds.SoundSource;
 import net.minecraft.world.item.ItemStack;
 
 public interface Shearable {
+    default void shear(ServerLevel world, SoundSource soundCategory, ItemStack shears, java.util.List<net.minecraft.world.item.ItemStack> drops) { this.shear(world, soundCategory, shears); } // Paper - Add drops to shear events
     void shear(ServerLevel world, SoundSource shearedSoundCategory, ItemStack shears);
 
     boolean readyForShearing();
     net.minecraft.world.level.Level level(); // Shearable API - expose default level needed for shearing.
+
+    // Paper start - custom shear drops; ensure all implementing entities override this
+    default java.util.List<net.minecraft.world.item.ItemStack> generateDefaultDrops(final ServerLevel serverLevel, final ItemStack shears) {
+        return java.util.Collections.emptyList();
+    }
+    // Paper end - custom shear drops
 }
diff --git a/src/main/java/net/minecraft/world/entity/animal/MushroomCow.java b/src/main/java/net/minecraft/world/entity/animal/MushroomCow.java
index d4d343e2d75a3e3ea787c3c68c64970f5b239f81..eea02ea0d99425a60575f5fa729782494d579080 100644
--- a/src/main/java/net/minecraft/world/entity/animal/MushroomCow.java
+++ b/src/main/java/net/minecraft/world/entity/animal/MushroomCow.java
@@ -46,6 +46,7 @@ import net.minecraft.world.level.storage.loot.BuiltInLootTables;
 // CraftBukkit start
 import org.bukkit.Bukkit;
 import org.bukkit.craftbukkit.event.CraftEventFactory;
+import org.bukkit.craftbukkit.inventory.CraftItemStack;
 import org.bukkit.event.entity.EntityDropItemEvent;
 import org.bukkit.event.entity.EntityTransformEvent;
 // CraftBukkit end
@@ -128,11 +129,18 @@ public class MushroomCow extends Cow implements Shearable, VariantHolder<Mushroo
                 ServerLevel worldserver = (ServerLevel) world;
 
                 // CraftBukkit start
-                if (!CraftEventFactory.handlePlayerShearEntityEvent(player, this, itemstack, hand)) {
-                    return InteractionResult.PASS;
+                // Paper start - custom shear drops
+                java.util.List<ItemStack> drops = this.generateDefaultDrops(worldserver, itemstack);
+                org.bukkit.event.player.PlayerShearEntityEvent event = CraftEventFactory.handlePlayerShearEntityEvent(player, this, itemstack, hand, drops);
+                if (event != null) {
+                    if (event.isCancelled()) {
+                        return InteractionResult.PASS;
+                    }
+                    drops = org.bukkit.craftbukkit.inventory.CraftItemStack.asNMSCopy(event.getDrops());
+                // Paper end - custom shear drops
                 }
                 // CraftBukkit end
-                this.shear(worldserver, SoundSource.PLAYERS, itemstack);
+                this.shear(worldserver, SoundSource.PLAYERS, itemstack, drops); // Paper - custom shear drops
                 this.gameEvent(GameEvent.SHEAR, player);
                 itemstack.hurtAndBreak(1, player, getSlotForHand(hand));
             }
@@ -168,22 +176,30 @@ public class MushroomCow extends Cow implements Shearable, VariantHolder<Mushroo
 
     @Override
     public void shear(ServerLevel world, SoundSource shearedSoundCategory, ItemStack shears) {
+    // Paper start - custom shear drops
+        this.shear(world, shearedSoundCategory, shears, this.generateDefaultDrops(world, shears));
+    }
+
+    @Override
+    public java.util.List<ItemStack> generateDefaultDrops(final ServerLevel serverLevel, final ItemStack shears) {
+        final java.util.List<ItemStack> drops = new it.unimi.dsi.fastutil.objects.ObjectArrayList<>();
+        this.dropFromShearingLootTable(serverLevel, BuiltInLootTables.SHEAR_MOOSHROOM, shears, (ignored, stack) -> {
+            for (int i = 0; i < stack.getCount(); ++i) drops.add(stack.copyWithCount(1));
+        });
+        return drops;
+    }
+
+    @Override
+    public void shear(ServerLevel world, SoundSource shearedSoundCategory, ItemStack shears, java.util.List<ItemStack> drops) {
+    // Paper end - custom shear drops
         world.playSound((Player) null, (Entity) this, SoundEvents.MOOSHROOM_SHEAR, shearedSoundCategory, 1.0F, 1.0F);
         this.convertTo(EntityType.COW, ConversionParams.single(this, false, false), (entitycow) -> {
             world.sendParticles(ParticleTypes.EXPLOSION, this.getX(), this.getY(0.5D), this.getZ(), 1, 0.0D, 0.0D, 0.0D, 0.0D);
-            this.dropFromShearingLootTable(world, BuiltInLootTables.SHEAR_MOOSHROOM, shears, (worldserver1, itemstack1) -> {
-                for (int i = 0; i < itemstack1.getCount(); ++i) {
-                    // CraftBukkit start
-                    ItemEntity entityitem = new ItemEntity(this.level(), this.getX(), this.getY(1.0D), this.getZ(), itemstack1.copyWithCount(1));
-                    EntityDropItemEvent event = new EntityDropItemEvent(this.getBukkitEntity(), (org.bukkit.entity.Item) entityitem.getBukkitEntity());
-                    Bukkit.getPluginManager().callEvent(event);
-                    if (event.isCancelled()) {
-                        continue;
-                    }
-                    worldserver1.addFreshEntity(entityitem);
-                    // CraftBukkit end
-                }
-
+            // Paper start - custom shear drops; moved drop generation to separate method
+            drops.forEach(drop -> {
+                ItemEntity entityitem = new ItemEntity(this.level(), this.getX(), this.getY(1.0D), this.getZ(), drop);
+                this.spawnAtLocation(world, entityitem);
+            // Paper end - custom shear drops; moved drop generation to separate method
             });
         }, EntityTransformEvent.TransformReason.SHEARED, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.SHEARED); // CraftBukkit
     }
diff --git a/src/main/java/net/minecraft/world/entity/animal/Sheep.java b/src/main/java/net/minecraft/world/entity/animal/Sheep.java
index 1bc638ab505850bffcbd08025de9664dd27e47c6..0b7f8b8d8cd119d83e67a2cee389bd6117ac4cf7 100644
--- a/src/main/java/net/minecraft/world/entity/animal/Sheep.java
+++ b/src/main/java/net/minecraft/world/entity/animal/Sheep.java
@@ -173,11 +173,18 @@ public class Sheep extends Animal implements Shearable {
 
                 if (this.readyForShearing()) {
                     // CraftBukkit start
-                    if (!CraftEventFactory.handlePlayerShearEntityEvent(player, this, itemstack, hand)) {
-                        return InteractionResult.PASS;
+                    // Paper start - custom shear drops
+                    java.util.List<ItemStack> drops = this.generateDefaultDrops(worldserver, itemstack);
+                    org.bukkit.event.player.PlayerShearEntityEvent event = CraftEventFactory.handlePlayerShearEntityEvent(player, this, itemstack, hand, drops);
+                    if (event != null) {
+                        if (event.isCancelled()) {
+                            return InteractionResult.PASS;
+                        }
+                        drops = org.bukkit.craftbukkit.inventory.CraftItemStack.asNMSCopy(event.getDrops());
+                    // Paper end - custom shear drops
                     }
                     // CraftBukkit end
-                    this.shear(worldserver, SoundSource.PLAYERS, itemstack);
+                    this.shear(worldserver, SoundSource.PLAYERS, itemstack, drops); // Paper - custom shear drops
                     this.gameEvent(GameEvent.SHEAR, player);
                     itemstack.hurtAndBreak(1, player, getSlotForHand(hand));
                     return InteractionResult.SUCCESS_SERVER;
@@ -192,11 +199,28 @@ public class Sheep extends Animal implements Shearable {
 
     @Override
     public void shear(ServerLevel world, SoundSource shearedSoundCategory, ItemStack shears) {
+        // Paper start - custom shear drops
+        this.shear(world, shearedSoundCategory, shears, this.generateDefaultDrops(world, shears));
+    }
+
+    @Override
+    public java.util.List<ItemStack> generateDefaultDrops(final ServerLevel serverLevel, final ItemStack shears) {
+        final java.util.List<ItemStack> drops = new it.unimi.dsi.fastutil.objects.ObjectArrayList<>();
+        this.dropFromShearingLootTable(serverLevel, BuiltInLootTables.SHEAR_SHEEP, shears, (ignored, stack) -> {
+            for (int i = 0; i < stack.getCount(); ++i) drops.add(stack.copyWithCount(1));
+        });
+        return drops;
+    }
+
+    @Override
+    public void shear(ServerLevel world, SoundSource shearedSoundCategory, ItemStack shears, java.util.List<ItemStack> drops) {
+        final ServerLevel worldserver1 = world; // Named for lambda consumption
+        // Paper end - custom shear drops
         world.playSound((Player) null, (Entity) this, SoundEvents.SHEEP_SHEAR, shearedSoundCategory, 1.0F, 1.0F);
-        this.dropFromShearingLootTable(world, BuiltInLootTables.SHEAR_SHEEP, shears, (worldserver1, itemstack1) -> {
-            for (int i = 0; i < itemstack1.getCount(); ++i) {
+        drops.forEach(itemstack1 -> { // Paper - custom drops - loop in generated default drops
+            if (true) { // Paper - custom drops - loop in generated default drops
                 this.forceDrops = true; // CraftBukkit
-                ItemEntity entityitem = this.spawnAtLocation(worldserver1, itemstack1.copyWithCount(1), 1.0F);
+                ItemEntity entityitem = this.spawnAtLocation(worldserver1, itemstack1, 1.0F); // Paper - custom drops - copy already done above
                 this.forceDrops = false; // CraftBukkit
 
                 if (entityitem != null) {
diff --git a/src/main/java/net/minecraft/world/entity/animal/SnowGolem.java b/src/main/java/net/minecraft/world/entity/animal/SnowGolem.java
index 975a9e35303bec29aedfbd554c38e4331cdfb174..fd9f6c17448a4d87f940eb8f544ecb9669068582 100644
--- a/src/main/java/net/minecraft/world/entity/animal/SnowGolem.java
+++ b/src/main/java/net/minecraft/world/entity/animal/SnowGolem.java
@@ -161,11 +161,18 @@ public class SnowGolem extends AbstractGolem implements Shearable, RangedAttackM
                 ServerLevel worldserver = (ServerLevel) world;
 
                 // CraftBukkit start
-                if (!CraftEventFactory.handlePlayerShearEntityEvent(player, this, itemstack, hand)) {
-                    return InteractionResult.PASS;
+                // Paper start - custom shear drops
+                java.util.List<ItemStack> drops = this.generateDefaultDrops(worldserver, itemstack);
+                org.bukkit.event.player.PlayerShearEntityEvent event = CraftEventFactory.handlePlayerShearEntityEvent(player, this, itemstack, hand, drops);
+                if (event != null) {
+                    if (event.isCancelled()) {
+                        return InteractionResult.PASS;
+                    }
+                    drops = org.bukkit.craftbukkit.inventory.CraftItemStack.asNMSCopy(event.getDrops());
+                // Paper end - custom shear drops
                 }
                 // CraftBukkit end
-                this.shear(worldserver, SoundSource.PLAYERS, itemstack);
+                this.shear(worldserver, SoundSource.PLAYERS, itemstack, drops); // Paper - custom shear drops
                 this.gameEvent(GameEvent.SHEAR, player);
                 itemstack.hurtAndBreak(1, player, getSlotForHand(hand));
             }
@@ -178,9 +185,26 @@ public class SnowGolem extends AbstractGolem implements Shearable, RangedAttackM
 
     @Override
     public void shear(ServerLevel world, SoundSource shearedSoundCategory, ItemStack shears) {
+    // Paper start - custom shear drops
+        this.shear(world, shearedSoundCategory, shears, this.generateDefaultDrops(world, shears));
+    }
+
+    @Override
+    public java.util.List<ItemStack> generateDefaultDrops(final ServerLevel serverLevel, final ItemStack shears) {
+        final java.util.List<ItemStack> drops = new it.unimi.dsi.fastutil.objects.ObjectArrayList<>();
+        this.dropFromShearingLootTable(serverLevel, BuiltInLootTables.SHEAR_SNOW_GOLEM, shears, (ignored, stack) -> {
+            drops.add(stack);
+        });
+        return drops;
+    }
+
+    @Override
+    public void shear(ServerLevel world, SoundSource shearedSoundCategory, ItemStack shears, java.util.List<ItemStack> drops) {
+        final ServerLevel worldserver1 = world; // Named for lambda consumption
+    // Paper end - custom shear drops
         world.playSound((Player) null, (Entity) this, SoundEvents.SNOW_GOLEM_SHEAR, shearedSoundCategory, 1.0F, 1.0F);
         this.setPumpkin(false);
-        this.dropFromShearingLootTable(world, BuiltInLootTables.SHEAR_SNOW_GOLEM, shears, (worldserver1, itemstack1) -> {
+        drops.forEach(itemstack1 -> { // Paper - custom shear drops
             this.forceDrops = true; // CraftBukkit
             this.spawnAtLocation(worldserver1, itemstack1, this.getEyeHeight());
             this.forceDrops = false; // CraftBukkit
diff --git a/src/main/java/net/minecraft/world/entity/monster/Bogged.java b/src/main/java/net/minecraft/world/entity/monster/Bogged.java
index be029746905aeba218684b883282649089657de3..975477663b6d76a69c006a89e440e21471b39b89 100644
--- a/src/main/java/net/minecraft/world/entity/monster/Bogged.java
+++ b/src/main/java/net/minecraft/world/entity/monster/Bogged.java
@@ -27,6 +27,7 @@ import net.minecraft.world.item.Items;
 import net.minecraft.world.level.Level;
 import net.minecraft.world.level.gameevent.GameEvent;
 import net.minecraft.world.level.storage.loot.BuiltInLootTables;
+import org.bukkit.craftbukkit.event.CraftEventFactory;
 
 public class Bogged extends AbstractSkeleton implements Shearable {
 
@@ -80,12 +81,19 @@ public class Bogged extends AbstractSkeleton implements Shearable {
                 ServerLevel worldserver = (ServerLevel) world;
 
                 // CraftBukkit start
-                if (!org.bukkit.craftbukkit.event.CraftEventFactory.handlePlayerShearEntityEvent(player, this, itemstack, hand)) {
-                    this.getEntityData().markDirty(Bogged.DATA_SHEARED); // CraftBukkit - mark dirty to restore sheared state to clients
-                    return InteractionResult.PASS;
+                // Paper start - custom shear drops
+                java.util.List<ItemStack> drops = this.generateDefaultDrops(worldserver, itemstack);
+                org.bukkit.event.player.PlayerShearEntityEvent event = CraftEventFactory.handlePlayerShearEntityEvent(player, this, itemstack, hand, drops);
+                if (event != null) {
+                    if (event.isCancelled()) {
+                        // this.getEntityData().markDirty(Bogged.DATA_SHEARED); // CraftBukkit - mark dirty to restore sheared state to clients // Paper - no longer needed
+                        return InteractionResult.PASS;
+                    }
+                    drops = org.bukkit.craftbukkit.inventory.CraftItemStack.asNMSCopy(event.getDrops());
+                // Paper end - custom shear drops
                 }
                 // CraftBukkit end
-                this.shear(worldserver, SoundSource.PLAYERS, itemstack);
+                this.shear(worldserver, SoundSource.PLAYERS, itemstack, drops); // Paper - custom shear drops
                 this.gameEvent(GameEvent.SHEAR, player);
                 itemstack.hurtAndBreak(1, player, getSlotForHand(hand));
             }
@@ -139,14 +147,33 @@ public class Bogged extends AbstractSkeleton implements Shearable {
 
     @Override
     public void shear(ServerLevel world, SoundSource shearedSoundCategory, ItemStack shears) {
+    // Paper start - custom shear drops
+        this.shear(world, shearedSoundCategory, shears, this.generateDefaultDrops(world, shears));
+    }
+
+    @Override
+    public java.util.List<ItemStack> generateDefaultDrops(final ServerLevel serverLevel, final ItemStack shears) {
+        final java.util.List<ItemStack> drops = new it.unimi.dsi.fastutil.objects.ObjectArrayList<>();
+        this.dropFromShearingLootTable(serverLevel, BuiltInLootTables.BOGGED_SHEAR, shears, (ignored, stack) -> {
+            drops.add(stack);
+        });
+        return drops;
+    }
+
+    @Override
+    public void shear(ServerLevel world, SoundSource shearedSoundCategory, ItemStack shears, java.util.List<ItemStack> drops) {
+    // Paper end - custom shear drops
         world.playSound((Player) null, (Entity) this, SoundEvents.BOGGED_SHEAR, shearedSoundCategory, 1.0F, 1.0F);
-        this.spawnShearedMushrooms(world, shears);
+        this.spawnShearedMushrooms(world, shears, drops); // Paper - custom shear drops
         this.setSheared(true);
     }
 
-    private void spawnShearedMushrooms(ServerLevel world, ItemStack shears) {
+    // Paper start - custom shear drops
+    private void spawnShearedMushrooms(ServerLevel world, ItemStack shears, java.util.List<ItemStack> drops) {
+        final ServerLevel worldserver1 = world; // Named for lambda consumption
         this.forceDrops = true; // Paper - Add missing forceDrop toggles
-        this.dropFromShearingLootTable(world, BuiltInLootTables.BOGGED_SHEAR, shears, (worldserver1, itemstack1) -> {
+        drops.forEach(itemstack1 -> {
+    // Paper end - custom shear drops
             this.spawnAtLocation(worldserver1, itemstack1, this.getBbHeight());
         });
         this.forceDrops = false; // Paper - Add missing forceDrop toggles
diff --git a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
index 1c87019f5eb8e51accef3dc7ee949cdf2bec8f72..ea4e1bf4bfe003c102ecce5958131aa86ec83864 100644
--- a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
+++ b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
@@ -1689,20 +1689,20 @@ public class CraftEventFactory {
         player.level().getCraftServer().getPluginManager().callEvent(event);
     }
 
-    public static BlockShearEntityEvent callBlockShearEntityEvent(Entity animal, org.bukkit.block.Block dispenser, CraftItemStack is) {
-        BlockShearEntityEvent bse = new BlockShearEntityEvent(dispenser, animal.getBukkitEntity(), is);
+    public static BlockShearEntityEvent callBlockShearEntityEvent(Entity animal, org.bukkit.block.Block dispenser, CraftItemStack is, List<ItemStack> drops) { // Paper - custom shear drops
+        BlockShearEntityEvent bse = new BlockShearEntityEvent(dispenser, animal.getBukkitEntity(), is, Lists.transform(drops, CraftItemStack::asCraftMirror)); // Paper - custom shear drops
         Bukkit.getPluginManager().callEvent(bse);
         return bse;
     }
 
-    public static boolean handlePlayerShearEntityEvent(net.minecraft.world.entity.player.Player player, Entity sheared, ItemStack shears, InteractionHand hand) {
+    public static PlayerShearEntityEvent handlePlayerShearEntityEvent(net.minecraft.world.entity.player.Player player, Entity sheared, ItemStack shears, InteractionHand hand, List<ItemStack> drops) { // Paper - custom shear drops
         if (!(player instanceof ServerPlayer)) {
-            return true;
+            return null; // Paper - custom shear drops
         }
 
-        PlayerShearEntityEvent event = new PlayerShearEntityEvent((Player) player.getBukkitEntity(), sheared.getBukkitEntity(), CraftItemStack.asCraftMirror(shears), (hand == InteractionHand.OFF_HAND ? EquipmentSlot.OFF_HAND : EquipmentSlot.HAND));
+        PlayerShearEntityEvent event = new PlayerShearEntityEvent((Player) player.getBukkitEntity(), sheared.getBukkitEntity(), CraftItemStack.asCraftMirror(shears), (hand == InteractionHand.OFF_HAND ? EquipmentSlot.OFF_HAND : EquipmentSlot.HAND), Lists.transform(drops, CraftItemStack::asCraftMirror)); // Paper - custom shear drops
         Bukkit.getPluginManager().callEvent(event);
-        return !event.isCancelled();
+        return event; // Paper - custom shear drops
     }
 
     public static Cancellable handleStatisticsIncrease(net.minecraft.world.entity.player.Player entityHuman, net.minecraft.stats.Stat<?> statistic, int current, int newValue) {
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
index 0b7bc5e83634a26ac6521694377b554c74c6bff0..ffd7ba14be38a117f5a7d7035a8d71a20fb1c4fc 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
@@ -74,6 +74,16 @@ public final class CraftItemStack extends ItemStack {
         return stack;
     }
 
+    // Paper start
+    public static java.util.List<net.minecraft.world.item.ItemStack> asNMSCopy(java.util.List<? extends ItemStack> originals) {
+        final java.util.List<net.minecraft.world.item.ItemStack> items = new java.util.ArrayList<>(originals.size());
+        for (final ItemStack original : originals) {
+            items.add(asNMSCopy(original));
+        }
+        return items;
+    }
+    // Paper end
+
     public static net.minecraft.world.item.ItemStack copyNMSStack(net.minecraft.world.item.ItemStack original, int amount) {
         net.minecraft.world.item.ItemStack stack = original.copy();
         stack.setCount(amount);
diff --git a/src/test/java/io/papermc/paper/entity/ShearableDropsTest.java b/src/test/java/io/papermc/paper/entity/ShearableDropsTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..5e6dfc93c86ec369b686f15ca066478e1635dbc3
--- /dev/null
+++ b/src/test/java/io/papermc/paper/entity/ShearableDropsTest.java
@@ -0,0 +1,35 @@
+package io.papermc.paper.entity;
+
+import io.github.classgraph.ClassGraph;
+import io.github.classgraph.ClassInfo;
+import io.github.classgraph.MethodInfoList;
+import io.github.classgraph.ScanResult;
+import java.util.ArrayList;
+import net.minecraft.world.entity.Shearable;
+import org.bukkit.support.environment.Normal;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+@Normal
+class ShearableDropsTest {
+
+    static Iterable<ClassInfo> parameters() {
+        try (ScanResult scanResult = new ClassGraph()
+            .enableClassInfo()
+            .enableMethodInfo()
+            .whitelistPackages("net.minecraft")
+            .scan()
+        ) {
+            return new ArrayList<>(scanResult.getClassesImplementing(Shearable.class.getName()));
+        }
+    }
+
+    @ParameterizedTest
+    @MethodSource("parameters")
+    void checkShearableDropOverrides(final ClassInfo classInfo) {
+        final MethodInfoList generateDefaultDrops = classInfo.getDeclaredMethodInfo("generateDefaultDrops");
+        assertEquals(1, generateDefaultDrops.size(), classInfo.getName() + " doesn't implement Shearable#generateDefaultDrops");
+    }
+}