Add unit tests for bugs

src/test/java/dotsandboxes/DotsAndBoxesGridTest.java

@@ -28,4 +28,60 @@ public class DotsAndBoxesGridTest {
     }
 
     // FIXME: You need to write tests for the two known bugs in the code.
+    @Test
+    public void testBoxCompleteAlgorithm() {
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(15, 8, 2);
+
+        assertFalse(grid.boxComplete(0, 0));
+        grid.drawVertical(0, 0, 1);
+        assertFalse(grid.boxComplete(0, 0));
+
+        assertFalse(grid.boxComplete(1, 0));
+        grid.drawVertical(1, 0, 1);
+        assertFalse(grid.boxComplete(1, 0));
+
+        assertFalse(grid.boxComplete(0, 0));
+        grid.drawHorizontal(0, 0, 1);
+        assertFalse(grid.boxComplete(0, 0));
+
+        assertFalse(grid.boxComplete(0, 1));
+        grid.drawHorizontal(0, 1, 1);
+        assertTrue(grid.boxComplete(0, 0));
+
+        assertFalse(grid.boxComplete(5, 5));
+        grid.drawHorizontal(5, 5, 1);
+        assertFalse(grid.boxComplete(5, 5));
+
+        assertFalse(grid.boxComplete(5, 6));
+        grid.drawHorizontal(5, 6, 1);
+        assertFalse(grid.boxComplete(5, 6));
+
+        assertFalse(grid.boxComplete(5, 5));
+        grid.drawVertical(5, 5, 1);
+        assertFalse(grid.boxComplete(5, 5));
+
+        assertFalse(grid.boxComplete(4, 5));
+        grid.drawVertical(6, 5, 1);
+        assertFalse(grid.boxComplete(6, 5));
+
+        assertTrue(grid.boxComplete(5, 5));
+    }
+
+    @Test
+    public void testDrawAlreadyDrawnLine() {
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(2, 2, 2);
+
+        // Draw a line at (0, 0) and claim a box
+        grid.drawHorizontal(0, 0, 1);
+
+        // Try to draw the same line again, it should throw an IllegalStateException
+        assertThrows(IllegalStateException.class, () -> grid.drawHorizontal(0, 0, 1));
+
+        // Draw a vertical line at (0, 0) and claim a box
+        grid.drawVertical(0, 0, 1);
+
+        // Try to draw the same vertical line again, it should throw an IllegalStateException
+        assertThrows(IllegalStateException.class, () -> grid.drawVertical(0, 0, 1));
+    }
+
 }