Crypto Square: adding test for empty text after normalized (#2129)

* adding test for empty text after normalized

* Update exercises/crypto-square/canonical-data.json

Co-authored-by: Katrina Owen <[email protected]>

Co-authored-by: Katrina Owen <[email protected]>

Author: izmirli

exercises/crypto-square/canonical-data.json

@@ -10,6 +10,15 @@
       },
       "expected": ""
     },
+    {
+      "uuid": "aad04a25-b8bb-4304-888b-581bea8e0040",
+      "description": "normalization results in empty plaintext",
+      "property": "ciphertext",
+      "input": {
+        "plaintext": "... --- ..."
+      },
+      "expected": ""
+    },
     {
       "uuid": "64131d65-6fd9-4f58-bdd8-4a2370fb481d",
       "description": "Lowercase",