More colour box tests.

tests/colourboxes_tests.py

@@ -8,9 +8,12 @@ class ColourboxesTest(unittest.TestCase):
     def test_generation(self):
         for args in ((1, 1),
                      (2, 2),
-                     (3, 3)):
+                     (3, 3),
+                     (4, 6)):
             boxes = generate_colour_boxes(*args)
-            print(boxes)
+            print()
+            for box in boxes:
+                print(box)
             self.assertTrue(makes_all_wells_white(boxes))
 
 if __name__ == '__main__':