fix(assassin): preserve external potion effects

src/main/java/games/dmg/spigottyrant/AssassinEffectController.java

@@ -3,6 +3,7 @@ package games.dmg.spigottyrant;
 import java.time.Clock;
 import java.time.Instant;
 import java.util.HashSet;
+import java.util.Objects;
 import java.util.Set;
 import java.util.UUID;
 import org.bukkit.GameMode;
@@ -17,6 +18,7 @@ public final class AssassinEffectController implements Runnable {
     private final Server server;
     private final PluginSettings settings;
     private final Clock clock;
+    private final EffectApplier effectApplier;
     private final Set<UUID> grantedFlight = new HashSet<>();
 
     public AssassinEffectController(
@@ -25,10 +27,21 @@ public final class AssassinEffectController implements Runnable {
         PluginSettings settings,
         Clock clock
     ) {
-        this.stateManager = stateManager;
-        this.server = server;
-        this.settings = settings;
-        this.clock = clock;
+        this(stateManager, server, settings, clock, new BukkitEffectApplier());
+    }
+
+    AssassinEffectController(
+        TyrantStateManager stateManager,
+        Server server,
+        PluginSettings settings,
+        Clock clock,
+        EffectApplier effectApplier
+    ) {
+        this.stateManager = Objects.requireNonNull(stateManager, "stateManager");
+        this.server = Objects.requireNonNull(server, "server");
+        this.settings = Objects.requireNonNull(settings, "settings");
+        this.clock = Objects.requireNonNull(clock, "clock");
+        this.effectApplier = Objects.requireNonNull(effectApplier, "effectApplier");
     }
 
     @Override
@@ -43,15 +56,15 @@ public final class AssassinEffectController implements Runnable {
             }
             applyWhileActive(
                 player, state, Ability.ASSASSIN_INVISIBILITY_ACTIVE,
-                PotionEffectType.INVISIBILITY, 0, false
+                EffectKind.INVISIBILITY, 0, false
             );
             applyWhileActive(
                 player, state, Ability.ASSASSIN_SPEED_ACTIVE,
-                PotionEffectType.SPEED, 0, true
+                EffectKind.SPEED, 0, true
             );
             applyWhileActive(
                 player, state, Ability.ASSASSIN_WEAKNESS_ACTIVE,
-                PotionEffectType.WEAKNESS, settings.assassinWeaknessLevel() - 1, true
+                EffectKind.WEAKNESS, settings.assassinWeaknessLevel() - 1, true
             );
             boolean jumpReady = !state.cooldownEnds().getOrDefault(
                 Ability.ASSASSIN_DOUBLE_JUMP, Instant.MIN
@@ -71,29 +84,52 @@ public final class AssassinEffectController implements Runnable {
         Player player,
         PlayerState state,
         Ability ability,
-        PotionEffectType type,
+        EffectKind effect,
         int amplifier,
         boolean particles
     ) {
         if (state.cooldownEnds().getOrDefault(ability, Instant.MIN).isAfter(clock.instant())) {
-            player.addPotionEffect(new PotionEffect(
-                type, EFFECT_TICKS, amplifier, false, particles, true
-            ));
-        } else {
-            player.removePotionEffect(type);
+            effectApplier.apply(player, effect, amplifier, particles);
         }
     }
 
     private void clear(Player player) {
-        player.removePotionEffect(PotionEffectType.INVISIBILITY);
-        player.removePotionEffect(PotionEffectType.SPEED);
-        player.removePotionEffect(PotionEffectType.WEAKNESS);
         if (grantedFlight.remove(player.getUniqueId()) && isSurvivalLike(player)) {
             player.setAllowFlight(false);
             player.setFlying(false);
         }
     }
 
+    enum EffectKind {
+        INVISIBILITY,
+        SPEED,
+        WEAKNESS
+    }
+
+    @FunctionalInterface
+    interface EffectApplier {
+        void apply(Player player, EffectKind effect, int amplifier, boolean particles);
+    }
+
+    private static final class BukkitEffectApplier implements EffectApplier {
+        @Override
+        public void apply(
+            Player player,
+            EffectKind effect,
+            int amplifier,
+            boolean particles
+        ) {
+            PotionEffectType type = switch (effect) {
+                case INVISIBILITY -> PotionEffectType.INVISIBILITY;
+                case SPEED -> PotionEffectType.SPEED;
+                case WEAKNESS -> PotionEffectType.WEAKNESS;
+            };
+            player.addPotionEffect(new PotionEffect(
+                type, EFFECT_TICKS, amplifier, false, particles, true
+            ));
+        }
+    }
+
     private static boolean isGrounded(Player player) {
         return !player.getLocation().clone().subtract(0.0, 0.1, 0.0)
             .getBlock().isPassable();

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

@@ -0,0 +1,145 @@
+package games.dmg.spigottyrant;
+
+import static org.mockito.Mockito.clearInvocations;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoInteractions;
+import static org.mockito.Mockito.when;
+
+import java.nio.file.Path;
+import java.time.Clock;
+import java.time.Instant;
+import java.time.ZoneOffset;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.UUID;
+import java.util.logging.Logger;
+import org.bukkit.Server;
+import org.bukkit.entity.Player;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+final class AssassinEffectControllerTest {
+    private static final Instant NOW = Instant.parse("2026-08-18T12:00:00Z");
+    private static final UUID PLAYER_ID = UUID.fromString(
+        "11111111-1111-1111-1111-111111111111"
+    );
+
+    @TempDir
+    Path temporaryDirectory;
+
+    @Test
+    void doesNotRemovePotionEffectsItDidNotApply() throws Exception {
+        TyrantStateManager stateManager = manager();
+        Player player = player();
+        Server server = server(player);
+        AssassinEffectController.EffectApplier effects = mock(
+            AssassinEffectController.EffectApplier.class
+        );
+        AssassinEffectController controller = controller(stateManager, server, effects);
+
+        controller.run();
+        controller.clearAll();
+
+        verifyNoInteractions(effects);
+    }
+
+    @Test
+    void stopsRefreshingManagedInvisibilityAfterItsDeadline() throws Exception {
+        TyrantStateManager stateManager = manager();
+        stateManager.updateGame(ignored -> runningGame());
+        stateManager.updatePlayer(PLAYER_ID, "Assassin", ignored -> assassin(Map.of(
+            Ability.ASSASSIN_INVISIBILITY_ACTIVE, NOW.plusSeconds(60),
+            Ability.ASSASSIN_DOUBLE_JUMP, NOW.plusSeconds(60)
+        )));
+        Player player = player();
+        Server server = server(player);
+        AssassinEffectController.EffectApplier effects = mock(
+            AssassinEffectController.EffectApplier.class
+        );
+        AssassinEffectController controller = controller(stateManager, server, effects);
+
+        controller.run();
+
+        verify(effects).apply(
+            player,
+            AssassinEffectController.EffectKind.INVISIBILITY,
+            0,
+            false
+        );
+
+        stateManager.updatePlayer(PLAYER_ID, "Assassin", ignored -> assassin(Map.of(
+            Ability.ASSASSIN_DOUBLE_JUMP, NOW.plusSeconds(60)
+        )));
+        clearInvocations(player, effects);
+        controller.run();
+
+        verifyNoInteractions(effects);
+    }
+
+    private TyrantStateManager manager() throws Exception {
+        return new TyrantStateManager(
+            new YamlTyrantStateRepository(temporaryDirectory.resolve("state.yml")),
+            Logger.getLogger("test")
+        );
+    }
+
+    private static AssassinEffectController controller(
+        TyrantStateManager stateManager,
+        Server server,
+        AssassinEffectController.EffectApplier effects
+    ) {
+        return new AssassinEffectController(
+            stateManager,
+            server,
+            PluginSettings.from(Map.of()),
+            Clock.fixed(NOW, ZoneOffset.UTC),
+            effects
+        );
+    }
+
+    private static Server server(Player player) {
+        Server server = mock(Server.class);
+        doReturn(List.of(player)).when(server).getOnlinePlayers();
+        return server;
+    }
+
+    private static Player player() {
+        Player player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(PLAYER_ID);
+        when(player.getName()).thenReturn("Assassin");
+        return player;
+    }
+
+    private static PlayerState assassin(Map<Ability, Instant> cooldowns) {
+        return new PlayerState(
+            PLAYER_ID,
+            "Assassin",
+            Optional.empty(),
+            Optional.empty(),
+            TyrantClass.ASSASSIN,
+            Optional.empty(),
+            cooldowns,
+            Set.of(),
+            List.of()
+        );
+    }
+
+    private static GameState runningGame() {
+        return new GameState(
+            GameLifecycle.RUNNING,
+            Optional.empty(),
+            Optional.empty(),
+            Optional.empty(),
+            Optional.empty(),
+            Optional.empty(),
+            java.time.Duration.ZERO,
+            0,
+            0,
+            Set.of()
+        );
+    }
+}