src/main/java/Monster/Shade.java

@@ -77,10 +77,11 @@ public class Shade extends Monster implements CanMove, CanAttack {
     }
 
     public boolean move(World world) {
+        updateDestinations(position, world);
+
         if (isDead()) {
             return false;
         }
-        updateDestinations(position, world);
         if (validDestinations.isEmpty()) {
             return false;
         }
@@ -90,15 +91,18 @@ public class Shade extends Monster implements CanMove, CanAttack {
     }
 
     public boolean moveTo(Position destination, World world) {
+        updateDestinations(position, world);
+
         if (isDead()) {
             return false;
         }
         if (playerIsAtPosition(destination, world)) {
             return false;
         }
-
+        if (validDestinations.isEmpty()) {
+            return false;
+        }
         position = destination;
-        updateDestinations(position, world);
         return true;
     }
 

src/main/java/Monster/Troll.java

@@ -3,7 +3,7 @@ package Monster;
 import Entity.Entity;
 import Entity.Player;
 import Entity.Position;
-import World.World;
+import World.*;
 
 import java.util.*;
 
@@ -82,10 +82,11 @@ public class Troll extends Monster implements CanMove, CanAttack {
     }
 
     public boolean move(World world) {
+        updateDestinations(position, world);
+
         if (isDead()) {
             return false;
         }
-        updateDestinations(position, world);
         if (validDestinations.isEmpty()) {
             return false;
         }
@@ -95,18 +96,18 @@ public class Troll extends Monster implements CanMove, CanAttack {
     }
 
     public boolean moveTo(Position destination, World world) {
+        updateDestinations(position, world);
+
         if (isDead()) {
             return false;
         }
-        if (playerIsAtPosition(destination, world)) {
-            return false;
-        }
         if (tileHasWrongHabitat(destination, world)) {
             return false;
         }
-
+        if (validDestinations.isEmpty()) {
+            return false;
+        }
         position = destination;
-        updateDestinations(position, world);
         return true;
     }
 
@@ -116,7 +117,7 @@ public class Troll extends Monster implements CanMove, CanAttack {
             if (move.cost <= energy) {
                 List<Position> destinations = move.findLegalDestinations(position);
                 for (Position destination : destinations) {
-                    if (noPlayerIsAtPosition(destination, world)) {
+                    if (tileHasWrongHabitat(destination, world)) {
                         validDestinations.add(destination);
                     }
                 }
@@ -124,22 +125,6 @@ public class Troll extends Monster implements CanMove, CanAttack {
         }
     }
 
-    private boolean playerIsAtPosition(Position position, World world) {
-        List<Entity> entitiesAtPosition = world.getPositionEntityMap().get(position);
-        if (isNull(entitiesAtPosition)) {
-            return false;
-        }
-        for (Entity entity : entitiesAtPosition) {
-            if (entity instanceof Player) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    private boolean noPlayerIsAtPosition(Position position, World world) {
-        return !playerIsAtPosition(position, world);
-    }
 
     private void enforceHealthValueBoundries() {
         if (health > MAX_HEALTH) {
@@ -164,6 +149,14 @@ public class Troll extends Monster implements CanMove, CanAttack {
     }
 
     private boolean tileHasWrongHabitat(Position position, World world) {
-        return !HABITAT.contains(world.getTileAtPosition(position).getBiome());
+        Tile destinationTile = world.getTileAtPosition(position);
+        if (Objects.isNull(destinationTile)) {
+            return false;
+        }
+        boolean hasWrongBiome = !HABITAT.contains(destinationTile.getBiome());
+        if (Objects.isNull(hasWrongBiome)) {
+            return false;
+        }
+        return hasWrongBiome;
     }
 }

src/test/java/MonsterTest.java

@@ -9,7 +9,6 @@ import static org.hamcrest.MatcherAssert.*;
 import static org.hamcrest.Matchers.*;
 import static org.mockito.Mockito.*;
 
-
 public class MonsterTest {
 
     private Shade defaultShade;