From eef8d55d86742a3fd46ddfc5540cebfcb2ec012e Mon Sep 17 00:00:00 2001
From: John Brick <johnpixel128@gmail.com>
Date: Thu, 19 Mar 2026 13:10:35 +0300
Subject: [PATCH] fix(A1Z26): return empty string instead of empty array for
 empty input (#2257)

---
 src/core/operations/A1Z26CipherDecode.mjs    |  2 +-
 tests/operations/index.mjs                   |  1 +
 tests/operations/tests/A1Z26CipherDecode.mjs | 33 ++++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 tests/operations/tests/A1Z26CipherDecode.mjs

diff --git a/src/core/operations/A1Z26CipherDecode.mjs b/src/core/operations/A1Z26CipherDecode.mjs
index 0b097c2b..cc9aafbf 100644
--- a/src/core/operations/A1Z26CipherDecode.mjs
+++ b/src/core/operations/A1Z26CipherDecode.mjs
@@ -76,7 +76,7 @@ class A1Z26CipherDecode extends Operation {
         const delim = Utils.charRep(args[0] || "Space");
 
         if (input.length === 0) {
-            return [];
+            return "";
         }
 
         const bites = input.split(delim);
diff --git a/tests/operations/index.mjs b/tests/operations/index.mjs
index fb03a5f7..3585e270 100644
--- a/tests/operations/index.mjs
+++ b/tests/operations/index.mjs
@@ -14,6 +14,7 @@
 import { setLongTestFailure, logTestReport } from "../lib/utils.mjs";
 
 import TestRegister from "../lib/TestRegister.mjs";
+import "./tests/A1Z26CipherDecode.mjs";
 import "./tests/AESKeyWrap.mjs";
 import "./tests/AlternatingCaps.mjs";
 import "./tests/AvroToJSON.mjs";
diff --git a/tests/operations/tests/A1Z26CipherDecode.mjs b/tests/operations/tests/A1Z26CipherDecode.mjs
new file mode 100644
index 00000000..97020e0b
--- /dev/null
+++ b/tests/operations/tests/A1Z26CipherDecode.mjs
@@ -0,0 +1,33 @@
+/**
+ * A1Z26 Cipher Decode tests
+ *
+ * @author brick-pixel
+ * @copyright Crown Copyright 2026
+ * @license Apache-2.0
+ */
+import TestRegister from "../../lib/TestRegister.mjs";
+
+TestRegister.addTests([
+    {
+        "name": "A1Z26 Cipher Decode: basic decode",
+        "input": "8 5 12 12 15",
+        "expectedOutput": "hello",
+        "recipeConfig": [
+            {
+                "op": "A1Z26 Cipher Decode",
+                "args": ["Space"]
+            }
+        ]
+    },
+    {
+        "name": "A1Z26 Cipher Decode: empty input returns empty string",
+        "input": "",
+        "expectedOutput": "",
+        "recipeConfig": [
+            {
+                "op": "A1Z26 Cipher Decode",
+                "args": ["Space"]
+            }
+        ]
+    }
+]);