[MOR] Fixed Shared Animosity incorrectly calculating creature count for boost effect. Closes #9428.

Mage.Sets/src/mage/cards/s/SharedAnimosity.java

@@ -68,8 +68,9 @@ class SharedAnimosityEffect extends OneShotEffect {
         }
         FilterPermanent filter = new FilterAttackingCreature();
         filter.add(new SharesCreatureTypePredicate(permanent));
-        filter.add(AnotherPredicate.instance);
+        // Can't use AnotherPredicate since that compares against SharedAnimosity, not against the attacker.
-        int count = game.getBattlefield().count(filter, source.getControllerId(), source, game);
+        // The attacker will match with itself once for the count, so subtract 1 from the total to get the number of other creatures that fit the filter.
+        int count = game.getBattlefield().count(filter, source.getControllerId(), source, game) - 1;
         if (count > 0) {
             game.addEffect(new BoostTargetEffect(
                     count, 0, Duration.EndOfTurn

Mage.Tests/src/test/java/org/mage/test/cards/single/mor/SharedAnimosityTest.java

@@ -0,0 +1,73 @@
+package org.mage.test.cards.single.mor;
+
+import mage.constants.PhaseStep;
+import mage.constants.Zone;
+import org.junit.Test;
+import org.mage.test.serverside.base.CardTestPlayerBase;
+
+/**
+ * {@link mage.cards.s.SharedAnimosity Shared Animosity}
+ * {2}{R}
+ * Enchantment
+ * Whenever a creature you control attacks, it gets +1/+0 until end of turn for each other attacking creature that shares a creature type with it.
+ *
+ * @author Alex-Vasile
+ */
+public class SharedAnimosityTest extends CardTestPlayerBase {
+
+    private static final String sharedAnimosity = "Shared Animosity";
+
+    /**
+     * Reported bug: https://github.com/magefree/mage/issues/9428
+     *      "Shared Animosity Giving a +1/+0 to a single attacking creature,
+     *      Silvar, Devourer of the Free attacked alone and got the +1".
+     */
+    @Test
+    public void attackingAlone() {
+        // 4/2
+        String silvar = "Silvar, Devourer of the Free";
+        addCard(Zone.BATTLEFIELD, playerA, sharedAnimosity);
+        addCard(Zone.BATTLEFIELD, playerA, silvar);
+
+        attack(1, playerA, silvar);
+
+        setStopAt(1, PhaseStep.POSTCOMBAT_MAIN);
+        execute();
+        assertPowerToughness(playerA, silvar, 4, 2); // Should not have gotten a boost
+        assertLife(playerB, 20 - 4);
+    }
+
+    /**
+     * Attack with 3 creatures.
+     * One shares types with both of the others.
+     * The other two only share a type with the 3rd, but not with each other.
+     */
+    @Test
+    public void attackingWithOthers() {
+        // 4/2
+        // Cat Nightmare
+        String silvar = "Silvar, Devourer of the Free";
+        // 2/2
+        // Cat Soldier
+        String ajanisPridemate = "Ajani's Pridemate";
+        // 1/5
+        // Gloom Pangolin
+        String gloomPangolin = "Gloom Pangolin";
+
+        addCard(Zone.BATTLEFIELD, playerA, sharedAnimosity);
+        addCard(Zone.BATTLEFIELD, playerA, ajanisPridemate);
+        addCard(Zone.BATTLEFIELD, playerA, gloomPangolin);
+        addCard(Zone.BATTLEFIELD, playerA, silvar);
+
+        attack(1, playerA, silvar);
+        attack(1, playerA, ajanisPridemate);
+        attack(1, playerA, gloomPangolin);
+
+        setStopAt(1, PhaseStep.POSTCOMBAT_MAIN);
+        execute();
+        assertPowerToughness(playerA, silvar, 4+2, 2); // Shares with both the pridemate and the pangolin
+        assertPowerToughness(playerA, ajanisPridemate, 2+1, 2); // Shares only with Silvar
+        assertPowerToughness(playerA, gloomPangolin, 1+1, 5); // Shares only with Silvar
+        assertLife(playerB, 20 - (4+2) - (2+1) - (1+1));
+    }
+}