add unit test

src/test/java/dotsandboxes/DotsAndBoxesGridTest.java

@@ -32,13 +32,13 @@ public class DotsAndBoxesGridTest {
     public void testBoxCompletionDetection() {
         DotsAndBoxesGrid grid = new DotsAndBoxesGrid(4, 3, 2);
         
-        // Draw only three sides of a box (not completing it)
+        // Draw four sides of a box (not completing it)
         grid.drawHorizontal(0, 0, 1); // Top
         grid.drawVertical(0, 0, 1);   // Left
         grid.drawHorizontal(0, 1, 1); // Bottom
+        grid.drawVertical(1,0,1); //Right
         
-        // Check if the box at (0, 0) is incorrectly identified as completed
-        assertTrue(grid.boxComplete(0, 0), "The box should not be completed.");
+        assertTrue(grid.boxComplete(0, 0), "The box should be completed.");
     }