diff --git a/src/test/java/dotsandboxes/DotsAndBoxesGridTest.java b/src/test/java/dotsandboxes/DotsAndBoxesGridTest.java
index 1946beda974d180686c65c0259a7b881e9a4eb5a..42c759cc77e3e9fc601ed838e5ed3add140ba3dc 100644
--- a/src/test/java/dotsandboxes/DotsAndBoxesGridTest.java
+++ b/src/test/java/dotsandboxes/DotsAndBoxesGridTest.java
@@ -28,4 +28,26 @@ public class DotsAndBoxesGridTest {
     }
 
     // FIXME: You need to write tests for the two known bugs in the code.
+
+    /* Test a grid with lines forming a complete box */
+    @Test
+    public void testIfBoxComplete() {
+        logger.info("test a grid with lines forming a complete box");
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(4, 3, 1);
+        assertFalse(grid.boxComplete(0, 0));
+
+    }
+
+    /* Test if drawing a duplicate line throws IllegalStateException */
+    @Test
+    public void testDrawDuplicateLine() {
+        logger.info("Test if drawing a duplicate line throws IllegalStateException");
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(5, 3, 2);
+        grid.drawHorizontal(1, 1, 1);
+
+        assertThrows(IllegalStateException.class, () -> {
+            grid.drawHorizontal(1, 1, 1);
+        });
+    }
+
 }