Issue has been fixed through commit 378c7bf3

Closes #1 (closed) 378c7bf3

src/main/java/dotsandboxes/DotsAndBoxesGrid.java

@@ -112,7 +112,8 @@ 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).
-        return true;
+        return (this.horizontals[x][y] && this.horizontals[x][y+1] && this.verticals[x][y] && this.verticals[x+1][y]);
+       
     }
 
     /** Tries to claim a box for a player. If the box is complete, sets the ownership and returns true. */
@@ -140,7 +141,9 @@ public class DotsAndBoxesGrid {
         }
 
         // FIXME: You need to throw an exception if the line was already drawn.
-
+        if (this.horizontals[x][y]) {
+            throw new IllegalStateException(String.format("horizontal line at [%d][%d] has been drawn already", x, y));
+        }
         this.horizontals[x][y] = true;
 
         // Try to claim the north or south boxes
@@ -171,7 +174,9 @@ public class DotsAndBoxesGrid {
         }
 
         // You need to throw an exception if the line was already drawn.
-
+        if (this.verticals[x][y]) {
+            throw new IllegalStateException(String.format("Vertical line at [%d][%d] has been drawn already", x, y));
+        }
         this.verticals[x][y] = true;
         // Try to claim the north or south boxes
         boolean claimE = claimBox(x, y, player);