Add unit tests for bugs

1. Test boxComplete detects completed boxes and returns false for incomplete boxes.

2. Test horizontal and vertical draw methods throw exceptions for already-drawn lines.

src/main/java/dotsandboxes/Main.java

@@ -11,7 +11,7 @@ public class Main {
         JFrame mainWindow = new JFrame("Dots and Boxes");
         DotsAndBoxesGrid grid = new DotsAndBoxesGrid(15, 8, 2);
 
-        // Updated with name and student numer
+        // Updated with name and student number
         JLabel label = new JLabel("Name: Chelsea Allen (220155519)");
 
         JPanel borderPane = new JPanel(new BorderLayout());

src/test/java/dotsandboxes/DotsAndBoxesGridTest.java

@@ -27,5 +27,70 @@ public class DotsAndBoxesGridTest {
         assertTrue(true);
     }
 
-    // FIXME: You need to write tests for the two known bugs in the code.
+    /*
+     * Test if boxComplete returns true for complete box
+     */
+    @Test
+    public void testBoxCompleteDetectsCompletedBoxes() {
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(15, 8, 2);
+        grid.drawHorizontal(0,0,1);
+        grid.drawHorizontal(0,1,1);
+        grid.drawVertical(0,0,1);
+        grid.drawVertical(1,0,1);
+        assertTrue(grid.boxComplete(0, 0));
+    }
+
+    /*
+     * 3 tests to determine if boxComplete returns false for incomplete box (no lines, 1 line, 2 lines)
+     */
+    @Test
+    public void testBoxCompleteNoLinesDrawn() {
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(20, 10, 2);
+        assertFalse(grid.boxComplete(0, 0));
+    }
+
+    @Test
+    public void testBoxCompleteOneLineDrawn() {
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(20, 10, 2);
+        grid.drawHorizontal(0, 0, 1);
+        assertFalse(grid.boxComplete(0, 0));
+    }
+
+    @Test
+    public void testBoxCompleteTwoLinesDrawn() {
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(20, 10, 2);
+        grid.drawHorizontal(0, 0, 1);
+        grid.drawVertical(0, 0, 1);
+        assertFalse(grid.boxComplete(0, 0));
+    }
+
+    /*
+     * Test if horizontal draw method throws exception for already-drawn lines
+     */
+    @Test
+    public void testDrawHorizontalDetectsRedrawnLines() {
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(20, 10, 2);
+
+        // draw a horizontal line at (0, 0) and claim a box
+        grid.drawHorizontal(0, 0, 1);
+
+        // attempt to draw the same line, should throw an IllegalStateException
+        assertThrows(IllegalStateException.class, () -> grid.drawHorizontal(0, 0, 1));
+
+    }
+
+    /*
+     * Test if vertical draw method throws exception for already-drawn lines
+     */
+    @Test
+    public void testDrawVerticalDetectsRedrawnLines() {
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(20, 10, 2);
+
+        // draw a vertical line at (0, 0) and claim a box
+        grid.drawVertical(0, 0, 1);
+
+        // attempt to draw the same line, should throw an IllegalStateException
+        assertThrows(IllegalStateException.class, () -> grid.drawVertical(0, 0, 1));
+
+    }
 }