Fix Biome#getSpawnableList returning an empty list for non-vanilla EnumCreatureTypes (#3611)

src/test/java/net/minecraftforge/test/BiomeSpawnableListTest.java

@@ -0,0 +1,70 @@
+package net.minecraftforge.test;
+
+import net.minecraft.block.material.Material;
+import net.minecraft.entity.EntityLiving;
+import net.minecraft.entity.EnumCreatureType;
+import net.minecraft.entity.passive.AbstractHorse;
+import net.minecraft.entity.passive.EntityHorse;
+import net.minecraft.init.Biomes;
+import net.minecraft.init.Bootstrap;
+import net.minecraft.world.biome.Biome;
+import net.minecraftforge.common.util.EnumHelper;
+import net.minecraftforge.fml.common.registry.EntityRegistry;
+import net.minecraftforge.fml.common.registry.ForgeTestRunner;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+@RunWith(ForgeTestRunner.class)
+public class BiomeSpawnableListTest
+{
+    private static EnumCreatureType creatureTypeHorse;
+
+    @BeforeClass
+    public static void setUp() throws Exception
+    {
+        Bootstrap.register();
+        creatureTypeHorse = EnumHelper.addCreatureType("biomespawnablelisttest:horse", AbstractHorse.class, 20, Material.AIR, true, true);
+    }
+
+    private boolean spawnableListContainsEntry(Class<? extends EntityLiving> entityClass, int weightedProb, int minGroupCount, int maxGroupCount,
+            EnumCreatureType creatureType, Biome biome)
+    {
+        boolean found = false;
+
+        for (Biome.SpawnListEntry spawnListEntry : biome.getSpawnableList(creatureType))
+        {
+            if (spawnListEntry.entityClass == entityClass && spawnListEntry.itemWeight == weightedProb && spawnListEntry.minGroupCount == minGroupCount
+                    && spawnListEntry.maxGroupCount == maxGroupCount)
+            {
+                found = true;
+                break;
+            }
+        }
+
+        return found;
+    }
+
+    @Test
+    public void testAddAndRemoveSpawn() throws Exception
+    {
+        final Class<EntityHorse> entityClass = EntityHorse.class;
+        final int weightedProb = 1;
+        final int minGroupCount = 1;
+        final int maxGroupCount = 20;
+        final Biome biome = Biomes.PLAINS;
+
+        // Test 1: We can add a spawn for the non-vanilla EnumCreatureType
+        EntityRegistry.addSpawn(entityClass, weightedProb, minGroupCount, maxGroupCount, creatureTypeHorse, biome);
+        final boolean containsEntryAfterAdd = spawnableListContainsEntry(entityClass, weightedProb, minGroupCount, maxGroupCount, creatureTypeHorse, biome);
+        assertTrue("The SpawnListEntry wasn't added", containsEntryAfterAdd);
+
+        // Test 2: We can remove a spawn for the non-vanilla EnumCreatureType
+        EntityRegistry.removeSpawn(entityClass, creatureTypeHorse, biome);
+        final boolean containsEntryAfterRemove = spawnableListContainsEntry(entityClass, weightedProb, minGroupCount, maxGroupCount, creatureTypeHorse, biome);
+        assertFalse("The SpawnListEntry wasn't removed", containsEntryAfterRemove);
+    }
+}