Krark's Thumb - fixed that it can generates too many flip triggers (#12152)

---------

Co-authored-by: Susucre <34709007+Susucre@users.noreply.github.com>

Mage.Sets/src/mage/cards/k/KrarksThumb.java

@@ -58,7 +58,11 @@ class KrarksThumbEffect extends ReplacementEffectImpl {
     @Override
     public boolean replaceEvent(GameEvent event, Ability source, Game game) {
         FlipCoinEvent flipCoinEvent = (FlipCoinEvent) event;
-        flipCoinEvent.setFlipCount(2 * flipCoinEvent.getFlipCount());
+        // If an effect tells you to flip more than one coin at once, this replaces each individual coin flip.
+        // For example, if an effect tells you to flip two coins, you’ll first flip two coins and ignore one, then
+        // flip two more coins and ignore one of those. You don’t flip four coins and ignore two.
+        // (2013-04-15)
+        flipCoinEvent.setFlipCount(1 + flipCoinEvent.getFlipCount());
         return false;
     }
 

Mage.Tests/src/test/java/org/mage/test/cards/single/mrd/KrarksThumbTest.java

@@ -0,0 +1,156 @@
+package org.mage.test.cards.single.mrd;
+
+import mage.abilities.TriggeredAbilityImpl;
+import mage.abilities.effects.common.GainLifeEffect;
+import mage.constants.PhaseStep;
+import mage.constants.Zone;
+import mage.game.Game;
+import mage.game.events.CoinFlippedEvent;
+import mage.game.events.GameEvent;
+import org.junit.Test;
+import org.mage.test.serverside.base.CardTestPlayerBase;
+
+/**
+ * @author Susucr
+ */
+public class KrarksThumbTest extends CardTestPlayerBase {
+
+    /**
+     * {@link mage.cards.k.KrarksThumb KrarksThumb}
+     * Legendary Artifact
+     * If you would flip a coin, instead flip two coins and ignore one.
+     */
+    private static final String thumb = "Krark's Thumb";
+
+    /**
+     * {@link mage.cards.g.GoblinTraprunner Goblin Traprunner} {3}{R}
+     * Creature — Goblin
+     * Whenever Goblin Traprunner attacks, flip three coins. For each flip you win, create a 1/1 red Goblin creature token that’s tapped and attacking.
+     */
+    private static final String runner = "Goblin Traprunner";
+
+    /**
+     * "Whenever you flip a coin, you gain 1 life for each coin flip."
+     */
+    private class KrarksThumbTestTriggeredAbility extends TriggeredAbilityImpl {
+
+        KrarksThumbTestTriggeredAbility() {
+            super(Zone.BATTLEFIELD, null, false);
+            setTriggerPhrase("Whenever you flip a coin, ");
+        }
+
+        private KrarksThumbTestTriggeredAbility(final KrarksThumbTestTriggeredAbility ability) {
+            super(ability);
+        }
+
+        @Override
+        public KrarksThumbTestTriggeredAbility copy() {
+            return new KrarksThumbTestTriggeredAbility(this);
+        }
+
+        @Override
+        public boolean checkEventType(GameEvent event, Game game) {
+            return event.getType() == GameEvent.EventType.COIN_FLIPPED;
+        }
+
+        @Override
+        public boolean checkTrigger(GameEvent event, Game game) {
+            if (!event.getPlayerId().equals(getControllerId())) {
+                return false;
+            }
+            CoinFlippedEvent flippedEvent = (CoinFlippedEvent) event;
+            int amount = flippedEvent.getFlipCount();
+            getEffects().clear();
+            getEffects().add(new GainLifeEffect(amount));
+            return true;
+        }
+    }
+
+    // Just to make sure of the test on flip is working, without Thumb interference
+    @Test
+    public void test_NoThumb() {
+        setStrictChooseMode(true);
+
+        addCard(Zone.BATTLEFIELD, playerA, runner);
+        addCustomCardWithAbility("Test Trigger", playerA, new KrarksThumbTestTriggeredAbility());
+
+        setFlipCoinResult(playerA, true);
+        setFlipCoinResult(playerA, false);
+        setFlipCoinResult(playerA, true);
+        attack(1, playerA, runner, playerB);
+        setChoice(playerA, "Whenever you flip a coin, you gain 1 life", 2); // stack triggers
+
+        setStopAt(1, PhaseStep.END_COMBAT);
+        execute();
+
+        assertPermanentCount(playerA, "Goblin Token", 2);
+        assertLife(playerA, 20 + 3);
+    }
+
+    @Test
+    public void test_OneThumb() {
+        setStrictChooseMode(true);
+
+        addCard(Zone.BATTLEFIELD, playerA, runner);
+        addCard(Zone.BATTLEFIELD, playerA, thumb);
+        addCustomCardWithAbility("Test Trigger", playerA, new KrarksThumbTestTriggeredAbility());
+
+        // First flip, + 1 reroll -- result success
+        setFlipCoinResult(playerA, true);
+        setFlipCoinResult(playerA, true);
+
+        // Second flip, + 1 reroll -- result success
+        setFlipCoinResult(playerA, false);
+        setFlipCoinResult(playerA, true);
+
+        // Third flip, + 1 reroll -- result failure
+        setFlipCoinResult(playerA, false);
+        setFlipCoinResult(playerA, false);
+
+        attack(1, playerA, runner, playerB);
+        setChoice(playerA, "Whenever you flip a coin, you gain 2 life", 2); // stack triggers
+
+        setStopAt(1, PhaseStep.END_COMBAT);
+        execute();
+
+        assertLife(playerA, 20 + 3 * 2);
+        assertPermanentCount(playerA, "Goblin Token", 2);
+    }
+
+    @Test
+    public void test_TwoThumb() {
+        setStrictChooseMode(true);
+
+        addCard(Zone.BATTLEFIELD, playerA, runner);
+        addCard(Zone.BATTLEFIELD, playerA, "Mirror Box"); // prevent legend rule as Thumb are legendary
+        addCard(Zone.BATTLEFIELD, playerA, thumb, 2);
+        addCustomCardWithAbility("Test Trigger", playerA, new KrarksThumbTestTriggeredAbility());
+
+        // First flip, + 2 rerolls -- result success
+        setFlipCoinResult(playerA, true);
+        setChoice(playerA, "Krark's Thumb"); // order replacement effects
+        setFlipCoinResult(playerA, false);
+        setFlipCoinResult(playerA, false);
+
+        // Second flip, + 2 rerolls -- result fail
+        setFlipCoinResult(playerA, false);
+        setChoice(playerA, "Krark's Thumb"); // order replacement effects
+        setFlipCoinResult(playerA, false);
+        setFlipCoinResult(playerA, false);
+
+        // Third flip, + 2 rerolls -- result success
+        setFlipCoinResult(playerA, true);
+        setChoice(playerA, "Krark's Thumb"); // order replacement effects
+        setFlipCoinResult(playerA, true);
+        setFlipCoinResult(playerA, false);
+
+        attack(1, playerA, runner, playerB);
+        setChoice(playerA, "Whenever you flip a coin, you gain 3 life", 2); // stack triggers
+
+        setStopAt(1, PhaseStep.END_COMBAT);
+        execute();
+
+        assertLife(playerA, 20 + 3 * 3);
+        assertPermanentCount(playerA, "Goblin Token", 2);
+    }
+}

Mage/src/main/java/mage/game/events/CoinFlippedEvent.java

@@ -12,12 +12,14 @@ public class CoinFlippedEvent extends GameEvent {
     private final boolean result;
     private final boolean chosen;
     private final boolean winnable;
+    private final int flipCount; // Number of flips that lead to this event. see [[Krark's Thumb]]
 
-    CoinFlippedEvent(UUID playerId, UUID sourceId, boolean result, boolean chosen, boolean winnable) {
+    CoinFlippedEvent(UUID playerId, UUID sourceId, int flipCount, boolean result, boolean chosen, boolean winnable) {
         super(GameEvent.EventType.COIN_FLIPPED, playerId, null, playerId);
         this.result = result;
         this.chosen = chosen;
         this.winnable = winnable;
+        this.flipCount = flipCount;
         this.setSourceId(sourceId);
     }
 
@@ -25,6 +27,10 @@ public class CoinFlippedEvent extends GameEvent {
         return result;
     }
 
+    public int getFlipCount() {
+        return flipCount;
+    }
+
     public String getResultName() {
         return CardUtil.booleanToFlipName(result);
     }

Mage/src/main/java/mage/game/events/FlipCoinEvent.java

@@ -54,6 +54,6 @@ public class FlipCoinEvent extends GameEvent {
     }
 
     public CoinFlippedEvent createFlippedEvent() {
-        return new CoinFlippedEvent(playerId, sourceId, result, chosen, winnable);
+        return new CoinFlippedEvent(playerId, sourceId, flipCount, result, chosen, winnable);
     }
 }