Added unit tests to DotsAndBoxesGridTest.java

src/test/java/dotsandboxes/DotsAndBoxesGridTest.java

@@ -28,4 +28,29 @@ public class DotsAndBoxesGridTest {
     }
 
     // FIXME: You need to write tests for the two known bugs in the code.
+    @Test
+    public void testBoxComplete() {
+        logger.info("Test whether the program recognises completed boxes");
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(3, 3, 1);
+        grid.drawHorizontal(0, 0, 1);
+        grid.drawHorizontal(0, 1, 1);
+        grid.drawVertical(0, 0, 1);
+        grid.drawVertical(1, 0, 1);
+        assertAll(
+                () -> assertTrue(grid.boxComplete(0, 0)),
+                () -> assertFalse(grid.boxComplete(1, 0))
+        );
+    }
+
+    @Test
+    public void testIllegalLine() {
+        logger.info("Ensure lines cannot be drawn over existing lines");
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(3, 3, 1);
+        grid.drawHorizontal(0, 0, 1);
+        grid.drawVertical(0, 0, 1);
+        assertAll(
+                () -> assertThrows(IllegalStateException.class, () -> grid.drawHorizontal(0, 0, 1), "The horizontal line was not drawn"),
+                () -> assertThrows(IllegalStateException.class, () -> grid.drawVertical(0, 0, 1), "The vertical line was not drawn")
+        );
+    }
 }