Fixed bugs related to this issue branch

src/main/java/dotsandboxes/DotsAndBoxesGrid.java

@@ -113,7 +113,11 @@ 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).
-        return true;
+        if (getHorizontal(x,y) && getHorizontal(x,y+1) && getVertical(x,y) && getVertical(x+1,y)) {
+            return true;
+        }
+
+        return false;
     }
 
     /** Tries to claim a box for a player. If the box is complete, sets the ownership and returns true. */
@@ -141,6 +145,10 @@ public class DotsAndBoxesGrid {
         }
 
         // FIXME: You need to throw an exception if the line was already drawn.
+        if (this.horizontals[x][y]) {
+            // Line already drawn, throw exception as requested
+            throw new RuntimeException("Line cannot be drawn twice.");
+        }
 
         this.horizontals[x][y] = true;
 
@@ -172,6 +180,10 @@ public class DotsAndBoxesGrid {
         }
 
         // You need to throw an exception if the line was already drawn.
+        if (this.verticals[x][y]) {
+            // Line already drawn, throw exception as requested
+            throw new RuntimeException("Line cannot be drawn twice.");
+        }
 
         this.verticals[x][y] = true;
         // Try to claim the north or south boxes