feat(tamer): capture and relocate mobs

src/test/java/games/dmg/spigottyrant/CapturedMobServiceTest.java

@@ -0,0 +1,46 @@
+package games.dmg.spigottyrant;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.UUID;
+import org.junit.jupiter.api.Test;
+
+final class CapturedMobServiceTest {
+    private final CapturedMobService service = new CapturedMobService();
+
+    @Test
+    void captureAddsSnapshotAndSuccessfulReleaseRemovesExactlyThatMob() {
+        UUID captureId = UUID.fromString("aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa");
+        PlayerState tamer = tamer();
+
+        PlayerState captured = service.capture(
+            tamer, captureId, "ZOMBIE", "{id:\"minecraft:zombie\"}"
+        );
+        CapturedMob mob = service.find(captured, captureId).orElseThrow();
+        PlayerState released = service.release(captured, captureId);
+
+        assertEquals("ZOMBIE", mob.entityType());
+        assertEquals("{id:\"minecraft:zombie\"}", mob.data().get("snapshot"));
+        assertEquals(java.util.List.of(), released.capturedMobs());
+    }
+
+    @Test
+    void enderDragonCanNeverBeCapturedAndMissingReleaseDoesNotMutate() {
+        assertThrows(IllegalArgumentException.class, () -> service.capture(
+            tamer(), UUID.randomUUID(), "ENDER_DRAGON", "snapshot"
+        ));
+        assertEquals(tamer(), service.release(tamer(), UUID.randomUUID()));
+    }
+
+    private static PlayerState tamer() {
+        return new PlayerState(
+            UUID.fromString("11111111-1111-1111-1111-111111111111"), "Tamer",
+            Optional.empty(), Optional.empty(), TyrantClass.TAMER, Optional.empty(),
+            Map.of(), Set.of(Ability.TAMER_CAPTURE), java.util.List.of()
+        );
+    }
+}