Fix Knowledge Pool exile target

Mage.Tests/src/test/java/org/mage/test/cards/single/mbs/KnowledgePoolTest.java

@@ -0,0 +1,61 @@
+package org.mage.test.cards.single.mbs;
+
+import mage.constants.PhaseStep;
+import mage.constants.Zone;
+import org.junit.Test;
+import org.mage.test.serverside.base.CardTestPlayerBase;
+
+/**
+ *
+ * @author Jmlundeen
+ */
+public class KnowledgePoolTest extends CardTestPlayerBase {
+
+    /*
+    Knowledge Pool
+    {6}
+    Artifact
+    Imprint - When Knowledge Pool enters the battlefield, each player exiles the top three cards of their library.
+    Whenever a player casts a spell from their hand, that player exiles it. If the player does, they may cast another nonland card exiled with Knowledge Pool without paying that card's mana cost.
+    */
+    private static final String knowledgePool = "Knowledge Pool";
+
+    /*
+    Lightning Bolt
+    {R}
+    Instant
+    Lightning Bolt deals 3 damage to any target.
+    */
+    private static final String lightningBolt = "Lightning Bolt";
+
+    /*
+    Shock
+    {R}
+    Instant
+    Shock deals 2 damage to any target.
+    */
+    private static final String shock = "Shock";
+
+    @Test
+    public void testKnowledgePool() {
+        addCard(Zone.BATTLEFIELD, playerA, "Mountain");
+        addCard(Zone.BATTLEFIELD, playerB, "Mountain");
+        addCard(Zone.BATTLEFIELD, playerA, knowledgePool);
+        addCard(Zone.HAND, playerA, lightningBolt);
+        addCard(Zone.HAND, playerB, shock);
+
+        castSpell(1, PhaseStep.PRECOMBAT_MAIN, playerA, lightningBolt, playerB);
+        setChoice(playerA, false);
+
+        castSpell(1, PhaseStep.POSTCOMBAT_MAIN, playerB, shock, playerA);
+        setChoice(playerB, true);
+        setChoice(playerB, lightningBolt);
+        addTarget(playerB, playerA);
+
+        setStrictChooseMode(true);
+        setStopAt(1, PhaseStep.END_TURN);
+        execute();
+        assertLife(playerA, 20 - 3); // shock exiled, bolt cast from knowledge pool
+        assertLife(playerB, 20); // bolt exiled, no card to cast from knowledge pool
+    }
+}