Fixed the bugs

src/main/java/dotsandboxes/DotsAndBoxesGrid.java

@@ -111,9 +111,11 @@ public class DotsAndBoxesGrid {
         }
 
         // A box is complete if the north and south horizontals and the east and west verticals have all been drawn.
-        // FIXME: You'll need to fix this code (after writing a test first).
+        if (this.verticals[x][y] && this.verticals[x+1][y] && this.horizontals[x][y] && this.horizontals[x][y+1]){
             return true;
         }
+        return false;
+    }
 
     /** Tries to claim a box for a player. If the box is complete, sets the ownership and returns true. */
     private boolean claimBox(int x, int y, int p) {
@@ -139,7 +141,9 @@ public class DotsAndBoxesGrid {
             throw new IndexOutOfBoundsException(String.format("y was %d, which is out of range. Range is 0 to %d", y, height));
         }
 
-        // FIXME: You need to throw an exception if the line was already drawn.
+        if (this.horizontals[x][y]){
+            throw new IllegalStateException(String.format("Attempted redraw of preexisting line"));
+        }
 
         this.horizontals[x][y] = true;
 
@@ -170,7 +174,10 @@ public class DotsAndBoxesGrid {
             throw new IndexOutOfBoundsException(String.format("y was %d, which is out of range. Range is 0 to %d", y, height - 1));
         }
 
-        // You need to throw an exception if the line was already drawn.
+        if (this.verticals[x][y]){
+            throw new IllegalStateException(String.format("Attempted redraw of preexisting line"));
+        }
+
 
         this.verticals[x][y] = true;
         // Try to claim the north or south boxes