Require visible scars in Cannon receipts

tests/test_cannon_canon.py

@@ -15,8 +15,10 @@ class CannonCanonTests(unittest.TestCase):
         forms = self.data["forms"]
         self.assertEqual(len(forms), 4)
         self.assertEqual(len({form["id"] for form in forms}), 4)
+        self.assertEqual(len({form["scar"] for form in forms}), 4)
         for form in forms:
             self.assertTrue(form["power"])
+            self.assertTrue(form["scar"])
             self.assertTrue(form["cost"])
             self.assertGreaterEqual(len(form["palette"]), 3)