Fix bugs in boxComplete and draw methods

src/main/java/dotsandboxes/DotsAndBoxesGrid.java

@@ -109,12 +109,10 @@ public class DotsAndBoxesGrid {
     if (x >= width - 1 || x < 0 || y >= height - 1 || y < 0) {
         return false;
     }
-
-        // 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 getHorizontal(x, y) && getHorizontal(x, y + 1) && getVertical(x, y) && getVertical(x + 1, y);
 }
 
+
     /** 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) {
         if (boxComplete(x, y)) {
@@ -139,11 +137,12 @@ 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 (horizontals[x][y]) {
+        throw new IllegalStateException("Line already drawn");
+    }
 
     this.horizontals[x][y] = true;
 
-        // Try to claim the north or south boxes
     boolean claimN = claimBox(x, y-1, player);
     boolean claimS = claimBox(x, y, player);
     if (claimN || claimS) {
@@ -156,6 +155,7 @@ public class DotsAndBoxesGrid {
     }
 }
 
+
     /**
      * "Draws" a vertical line, from grid point (x, y) to (x, y + 1). (i.e. sets that line to true)
      * @param x
@@ -170,10 +170,11 @@ 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 (verticals[x][y]) {
+        throw new IllegalStateException("Line already drawn");
+    }
 
     this.verticals[x][y] = true;
-        // Try to claim the north or south boxes
     boolean claimE = claimBox(x, y, player);
     boolean claimW = claimBox(x-1, y, player);
     if (claimE || claimW) {
@@ -184,9 +185,7 @@ public class DotsAndBoxesGrid {
         notifyObservers();
         return false;
     }
-
 }
-
     public boolean gameComplete() {
         // Students who took COSC250 might recognise this style of code. This is Java's version of higher order functions.
         // The grid is complete if "for all rows, all the boxes in that row have a non-zero owner"