Fixed both bugs in code - inital test. Pending futher in-depth tests. Unit tests pass now.

src/main/java/dotsandboxes/DotsAndBoxesGrid.java

@@ -107,17 +107,57 @@ public class DotsAndBoxesGrid {
      * @return true if all four sides have been drawn.
      */
     public boolean boxComplete(int x, int y) {
-        //Tests for invalid box references.
+        //Tests for invalid box references.\
+        //not boundary
         if (x >= width - 1 || x < 0 || y >= height - 1 || y < 0) {
             return false;
         }
-        
+        else if (getHorizontal(x, y) && getHorizontal(x, (y-1)) && getVertical(x, y) && getVertical((x+1), y)) {
+            //south box
+            return true;
+        }
+        else if (getHorizontal(x, y) && getHorizontal(x, (y+1)) && getVertical(x, y) && getVertical((x+1), y)) {
+            //north box
+            return true;
+        }
+        else {
+            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 if box complete, false if not.
-        return true;
     }
 
+    public int boundaryLine(int x, int y) {
+        int boundaryFlag = 0;
+        if (x == 1) {
+            if (y > 1) {
+                boundaryFlag = 1;
+            }
+            //left vertical boundary.
+        }
+        else if (x == width) {
+            if (y > 1) {
+                boundaryFlag = 2;
+                //check u, d, l
+            }
+            //right vertical boundary
+        }
+        else if (y == 1) {
+            boundaryFlag = 3;
+            //bottom of grid
+            //u, l, r
+        }
+        else if (y == height) {
+            boundaryFlag = 4;
+            //top of grid
+            //d, l, r
+        }
+        else {
+            return boundaryFlag;
+        }
+        return boundaryFlag;
+    }
     /** 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)) {
@@ -141,23 +181,29 @@ public class DotsAndBoxesGrid {
         if (y >= height || y < 0) {
             throw new IndexOutOfBoundsException(String.format("y was %d, which is out of range. Range is 0 to %d", y, height));
         }
+        if (this.horizontals[x][y] == true) {
+            throw new IllegalStateException(String.format("Warning: This line has already been drawn by a player!"));
+        }
+        else {
+            this.horizontals[x][y] = true;
+
+            //Uses the coords from what was just drawn above to see if the drawn line will complete either a top or bottom box. Checking done through boxComplete called in claimBox.
+            boolean claimN = claimBox(x, y-1, player); //
+            boolean claimS = claimBox(x, y, player);
+            if (claimN || claimS) {
+                notifyObservers();
+                return true;
+            } else {
+                nextPlayer();
+                notifyObservers();
+                return false;
+            }
+        }
         
 
         // FIXME: You need to throw an exception if the line was already drawn.
 
-        this.horizontals[x][y] = true;
 
-        //Uses the coords from what was just drawn above to see if the drawn line will complete either a top or bottom box. Checking done through boxComplete called in claimBox.
-        boolean claimN = claimBox(x, y-1, player); //
-        boolean claimS = claimBox(x, y, player);
-        if (claimN || claimS) {
-            notifyObservers();
-            return true;
-        } else {
-            nextPlayer();
-            notifyObservers();
-            return false;
-        }
     }
 
     /**
@@ -173,21 +219,27 @@ public class DotsAndBoxesGrid {
         if (y >= height - 1 || y < 0) {
             throw new IndexOutOfBoundsException(String.format("y was %d, which is out of range. Range is 0 to %d", y, height - 1));
         }
+        if (this.verticals[x][y] == true) {
+            throw new IllegalStateException(String.format("This line has already been drawn by another player!"));
+        }
+        else {
+            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) {
+                notifyObservers();
+                return true;
+            } else {
+                nextPlayer();
+                notifyObservers();
+                return false;
+            }
+        }
 
         // You need to throw an exception if the line was 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) {
-            notifyObservers();
-            return true;
-        } else {
-            nextPlayer();
-            notifyObservers();
-            return false;
-        }
+
 
     }