bolt8

commit 73edeb4503c449cfdafd7a0817ce686b297960a8
parent 4af1d8ed7eac2b14b8d4ada83183237f1625ac11
Author: Jared Tobin <jared@jtobin.io>
Date:   Sun, 25 Jan 2026 09:43:27 +0400

test: add bounds check to flip_byte helper

Guard against out-of-bounds index to give a clear error message
rather than crashing on BS.index. Addresses review finding from
REVIEW-ebf75f4.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Diffstat:
M
test/Main.hs
 | 
10
++++++----

1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/test/Main.hs b/test/Main.hs
@@ -489,10 +489,12 @@ test_decrypt_short_packet = do
 
 -- flip one byte in a bytestring at given index
 flip_byte :: Int -> BS.ByteString -> BS.ByteString
-flip_byte i bs =
-  let (pre, post) = BS.splitAt i bs
-      b = BS.index post 0
-  in pre <> BS.cons (b `xor` 0xff) (BS.drop 1 post)
+flip_byte i bs
+  | i < 0 || i >= BS.length bs = error "flip_byte: index out of bounds"
+  | otherwise =
+      let (pre, post) = BS.splitAt i bs
+          b = BS.index post 0
+      in pre <> BS.cons (b `xor` 0xff) (BS.drop 1 post)
 
 -- utilities -----------------------------------------------------------------