* Fixed possible game exception with empty library and commander movement (fixes #6952).

Mage.Tests/src/test/java/org/mage/test/commander/duel/CastCommanderTest.java

@@ -1,6 +1,8 @@
 
 package org.mage.test.commander.duel;
 
+import java.util.ArrayList;
+import mage.cards.Card;
 import mage.constants.PhaseStep;
 import mage.constants.Zone;
 import mage.game.permanent.Permanent;
@@ -93,4 +95,41 @@ public class CastCommanderTest extends CardTestCommanderDuelBase {
         assertGraveyardCount(playerA, "Coiled Tinviper", 1);
         assertTappedCount("Forest", false, 3);
     }  
+    
+    // https://github.com/magefree/mage/issues/6952
+    
+    @Test
+    public void testCastCommanderAndUnexpectedlyAbsent() {
+        setStrictChooseMode(true);
+        
+        playerA.getLibrary().clear();
+        
+        addCard(Zone.BATTLEFIELD, playerA, "Swamp", 2);
+        addCard(Zone.BATTLEFIELD, playerA, "Plains", 5);
+
+        // Put target nonland permanent into its owner's library just beneath the top X cards of that library.
+        addCard(Zone.HAND, playerA, "Unexpectedly Absent"); // Instant {X}{W}{W}
+
+        castSpell(1, PhaseStep.PRECOMBAT_MAIN, playerA, "Ob Nixilis of the Black Oath"); // {3}{B}{B}
+
+        castSpell(1, PhaseStep.PRECOMBAT_MAIN, playerA, "Unexpectedly Absent", "Ob Nixilis of the Black Oath");
+        setChoice(playerA, "X=0");
+        setChoice(playerA, "Yes"); // Move Commander to command zone instead library?
+
+        setStopAt(1, PhaseStep.BEGIN_COMBAT);
+        execute();
+
+        assertAllCommandsUsed();
+        
+        assertPermanentCount(playerA, "Ob Nixilis of the Black Oath", 0);
+        assertLibraryCount(playerA, "Ob Nixilis of the Black Oath", 0);
+        assertCommandZoneCount(playerA, "Ob Nixilis of the Black Oath", 1);
+
+        assertLibraryCount(playerA, 0);
+
+        assertGraveyardCount(playerA, "Unexpectedly Absent", 1);
+
+        assertLife(playerA, 40);
+        assertLife(playerB, 40);        
+    }        
 }

Mage/src/main/java/mage/players/PlayerImpl.java

@@ -614,9 +614,9 @@ public abstract class PlayerImpl implements Player, Serializable {
                     && this.hasOpponent(sourceControllerId, game)
                     && game.getContinuousEffects().asThough(this.getId(), AsThoughEffectType.HEXPROOF, null, sourceControllerId, game) == null
                     && abilities.stream()
-                    .filter(HexproofBaseAbility.class::isInstance)
-                    .map(HexproofBaseAbility.class::cast)
-                    .anyMatch(ability -> ability.checkObject(source, game))) {
+                            .filter(HexproofBaseAbility.class::isInstance)
+                            .map(HexproofBaseAbility.class::cast)
+                            .anyMatch(ability -> ability.checkObject(source, game))) {
                 return false;
             }
 
@@ -656,7 +656,7 @@ public abstract class PlayerImpl implements Player, Serializable {
                 game.informPlayers(getLogName() + " discards down to "
                         + this.maxHandSize
                         + (this.maxHandSize == 1
-                        ? " hand card" : " hand cards"));
+                                ? " hand card" : " hand cards"));
             }
             discard(hand.size() - this.maxHandSize, false, null, game);
         }
@@ -805,7 +805,7 @@ public abstract class PlayerImpl implements Player, Serializable {
         }
         GameEvent gameEvent = GameEvent.getEvent(GameEvent.EventType.DISCARD_CARD,
                 card.getId(), source == null
-                        ? null : source.getSourceId(), playerId);
+                ? null : source.getSourceId(), playerId);
         gameEvent.setFlag(source != null); // event from effect or from cost (source == null)
         if (game.replaceEvent(gameEvent, source)) {
             return false;
@@ -996,14 +996,16 @@ public abstract class PlayerImpl implements Player, Serializable {
             } else {
                 if (card.moveToZone(Zone.LIBRARY, source.getSourceId(), game, true)
                         && !(card instanceof PermanentToken) && !card.isCopy()) {
-                    card = getLibrary().removeFromTop(game);
-                    getLibrary().putCardToTopXPos(card, xFromTheTop, game);
-                    game.informPlayers(card.getLogName()
-                            + " is put into "
-                            + getLogName()
-                            + "'s library "
-                            + CardUtil.numberToOrdinalText(xFromTheTop)
-                            + " from the top");
+                    Card cardInLib = getLibrary().getFromTop(game);
+                    if (cardInLib != null && cardInLib.getId().equals(card.getId())) { // check needed because e.g. commander can go to command zone
+                        getLibrary().putCardToTopXPos(cardInLib, xFromTheTop, game);
+                        game.informPlayers(cardInLib.getLogName()
+                                + " is put into "
+                                + getLogName()
+                                + "'s library "
+                                + CardUtil.numberToOrdinalText(xFromTheTop)
+                                + " from the top");
+                    }
                 } else {
                     return false;
                 }
@@ -1854,9 +1856,9 @@ public abstract class PlayerImpl implements Player, Serializable {
     }
 
     private List<Permanent> getPermanentsThatCanBeUntapped(Game game,
-                                                           List<Permanent> canBeUntapped,
-                                                           RestrictionUntapNotMoreThanEffect handledEffect,
-                                                           Map<Entry<RestrictionUntapNotMoreThanEffect, Set<Ability>>, Integer> notMoreThanEffectsUsage) {
+            List<Permanent> canBeUntapped,
+            RestrictionUntapNotMoreThanEffect handledEffect,
+            Map<Entry<RestrictionUntapNotMoreThanEffect, Set<Ability>>, Integer> notMoreThanEffectsUsage) {
         List<Permanent> leftForUntap = new ArrayList<>();
         // select permanents that can still be untapped
         for (Permanent permanent : canBeUntapped) {
@@ -2569,7 +2571,7 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public boolean searchLibrary(TargetCardInLibrary target, Ability source, Game game, UUID targetPlayerId,
-                                 boolean triggerEvents) {
+            boolean triggerEvents) {
         //20091005 - 701.14c
         Library searchedLibrary = null;
         String searchInfo = null;
@@ -2719,7 +2721,7 @@ public abstract class PlayerImpl implements Player, Serializable {
      * @param winnable
      * @param appliedEffects
      * @return if winnable, true if player won the toss, if not winnable, true
-     * for heads and false for tails
+     *         for heads and false for tails
      */
     @Override
     public boolean flipCoin(Ability source, Game game, boolean winnable, List<UUID> appliedEffects) {
@@ -2813,11 +2815,11 @@ public abstract class PlayerImpl implements Player, Serializable {
      * @param numberPlanarSides The number of chaos sides the planar die
      *                          currently has (normally 1)
      * @return the outcome that the player rolled. Either ChaosRoll, PlanarRoll
-     * or NilRoll
+     *         or NilRoll
      */
     @Override
     public PlanarDieRoll rollPlanarDie(Game game, List<UUID> appliedEffects, int numberChaosSides,
-                                       int numberPlanarSides) {
+            int numberPlanarSides) {
         int result = RandomUtil.nextInt(9) + 1;
         PlanarDieRoll roll = PlanarDieRoll.NIL_ROLL;
         if (numberChaosSides + numberPlanarSides > 9) {
@@ -2894,7 +2896,7 @@ public abstract class PlayerImpl implements Player, Serializable {
             boolean withCost = false;
             Abilities<ActivatedManaAbilityImpl> manaAbilities
                     = permanent.getAbilities().getAvailableActivatedManaAbilities(Zone.BATTLEFIELD, game);
-            for (Iterator<ActivatedManaAbilityImpl> it = manaAbilities.iterator(); it.hasNext(); ) {
+            for (Iterator<ActivatedManaAbilityImpl> it = manaAbilities.iterator(); it.hasNext();) {
                 ActivatedManaAbilityImpl ability = it.next();
                 if (canUse == null) {
                     canUse = permanent.canUseActivatedAbilities(game);
@@ -2935,7 +2937,7 @@ public abstract class PlayerImpl implements Player, Serializable {
         boolean anAbilityWasUsed = true;
         while (anAbilityWasUsed && !sourceWithCosts.isEmpty()) {
             anAbilityWasUsed = false;
-            for (Iterator<Abilities<ActivatedManaAbilityImpl>> iterator = sourceWithCosts.iterator(); iterator.hasNext(); ) {
+            for (Iterator<Abilities<ActivatedManaAbilityImpl>> iterator = sourceWithCosts.iterator(); iterator.hasNext();) {
                 Abilities<ActivatedManaAbilityImpl> manaAbilities = iterator.next();
                 boolean used = availableMana.addManaWithCost(manaAbilities, game);
                 if (used) {
@@ -3619,7 +3621,7 @@ public abstract class PlayerImpl implements Player, Serializable {
      *
      * @param game
      * @return A Set of cardIds that are playable and amount of playable
-     * abilities
+     *         abilities
      */
     @Override
     public Map<UUID, Integer> getPlayableObjects(Game game, Zone zone) {
@@ -3827,7 +3829,7 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public boolean canPaySacrificeCost(Permanent permanent, UUID sourceId,
-                                       UUID controllerId, Game game
+            UUID controllerId, Game game
     ) {
         return sacrificeCostFilter == null || !sacrificeCostFilter.match(permanent, sourceId, controllerId, game);
     }
@@ -3980,8 +3982,8 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public boolean moveCards(Card card, Zone toZone,
-                             Ability source, Game game,
-                             boolean tapped, boolean faceDown, boolean byOwner, List<UUID> appliedEffects
+            Ability source, Game game,
+            boolean tapped, boolean faceDown, boolean byOwner, List<UUID> appliedEffects
     ) {
         Set<Card> cardList = new HashSet<>();
         if (card != null) {
@@ -3992,22 +3994,22 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public boolean moveCards(Cards cards, Zone toZone,
-                             Ability source, Game game
+            Ability source, Game game
     ) {
         return moveCards(cards.getCards(game), toZone, source, game);
     }
 
     @Override
     public boolean moveCards(Set<Card> cards, Zone toZone,
-                             Ability source, Game game
+            Ability source, Game game
     ) {
         return moveCards(cards, toZone, source, game, false, false, false, null);
     }
 
     @Override
     public boolean moveCards(Set<Card> cards, Zone toZone,
-                             Ability source, Game game,
-                             boolean tapped, boolean faceDown, boolean byOwner, List<UUID> appliedEffects
+            Ability source, Game game,
+            boolean tapped, boolean faceDown, boolean byOwner, List<UUID> appliedEffects
     ) {
         if (cards.isEmpty()) {
             return true;
@@ -4109,8 +4111,8 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public boolean moveCardsToExile(Card card, Ability source,
-                                    Game game, boolean withName, UUID exileId,
-                                    String exileZoneName
+            Game game, boolean withName, UUID exileId,
+            String exileZoneName
     ) {
         Set<Card> cards = new HashSet<>();
         cards.add(card);
@@ -4119,8 +4121,8 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public boolean moveCardsToExile(Set<Card> cards, Ability source,
-                                    Game game, boolean withName, UUID exileId,
-                                    String exileZoneName
+            Game game, boolean withName, UUID exileId,
+            String exileZoneName
     ) {
         if (cards.isEmpty()) {
             return true;
@@ -4136,14 +4138,14 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public boolean moveCardToHandWithInfo(Card card, UUID sourceId,
-                                          Game game
+            Game game
     ) {
         return this.moveCardToHandWithInfo(card, sourceId, game, true);
     }
 
     @Override
     public boolean moveCardToHandWithInfo(Card card, UUID sourceId,
-                                          Game game, boolean withName
+            Game game, boolean withName
     ) {
         boolean result = false;
         Zone fromZone = game.getState().getZone(card.getId());
@@ -4168,7 +4170,7 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public Set<Card> moveCardsToGraveyardWithInfo(Set<Card> allCards, Ability source,
-                                                  Game game, Zone fromZone
+            Game game, Zone fromZone
     ) {
         UUID sourceId = source == null ? null : source.getSourceId();
         Set<Card> movedCards = new LinkedHashSet<>();
@@ -4176,7 +4178,7 @@ public abstract class PlayerImpl implements Player, Serializable {
             // identify cards from one owner
             Cards cards = new CardsImpl();
             UUID ownerId = null;
-            for (Iterator<Card> it = allCards.iterator(); it.hasNext(); ) {
+            for (Iterator<Card> it = allCards.iterator(); it.hasNext();) {
                 Card card = it.next();
                 if (cards.isEmpty()) {
                     ownerId = card.getOwnerId();
@@ -4239,7 +4241,7 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public boolean moveCardToGraveyardWithInfo(Card card, UUID sourceId,
-                                               Game game, Zone fromZone
+            Game game, Zone fromZone
     ) {
         if (card == null) {
             return false;
@@ -4268,8 +4270,8 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public boolean moveCardToLibraryWithInfo(Card card, UUID sourceId,
-                                             Game game, Zone fromZone,
-                                             boolean toTop, boolean withName
+            Game game, Zone fromZone,
+            boolean toTop, boolean withName
     ) {
         if (card == null) {
             return false;
@@ -4334,7 +4336,7 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public boolean moveCardToExileWithInfo(Card card, UUID exileId, String exileName, UUID sourceId,
-                                           Game game, Zone fromZone, boolean withName) {
+            Game game, Zone fromZone, boolean withName) {
         if (card == null) {
             return false;
         }
@@ -4358,7 +4360,7 @@ public abstract class PlayerImpl implements Player, Serializable {
                     game.informPlayers(this.getLogName() + " moves " + (withName ? card.getLogName()
                             + (card.isCopy() ? " (Copy)" : "") : "a card face down") + ' '
                             + (fromZone != null ? "from " + fromZone.toString().toLowerCase(Locale.ENGLISH)
-                            + ' ' : "") + "to the exile zone");
+                                    + ' ' : "") + "to the exile zone");
                 }
 
             }