Fix the balance checks for a funds transfer test

An AI agent wrote a test for transferFunds(from, to, amount) in your payments service. It mocked the database and asserted only that the call returned { success: true }, so a transfer that debits twice or credits nothing still passed. Your team now checks both balances after every transfer instead.

An assistant wrote transfer_violations(from_before_cents, to_before_cents, from_after_cents, to_after_cents, amount_cents). It is in the editor. It has a bug. Find it and fix it.

Input and output:

• from_before_cents and to_before_cents: the sender's and the receiver's balances before the transfer, as integer cents.
• from_after_cents and to_after_cents: the same two balances after the transfer, as integer cents. Any balance can be negative.
• amount_cents: the amount the transfer was asked to move, as integer cents. It can be 0 or negative.
• Return the list of violations, empty when the transfer is correct.

Rules the tests check:

• Run every check below, in this order, and add each one that applies:
  1. invalid_amount when amount_cents is 0 or less.
  2. source_debit_wrong when from_after_cents is not exactly from_before_cents minus amount_cents.
  3. destination_credit_wrong when to_after_cents is not exactly to_before_cents plus amount_cents.
  4. total_not_conserved when the two balances after do not add up to the same sum as the two balances before.
  5. source_overdrawn when from_after_cents is below 0.
• invalid_amount does not stop the other checks. They still use amount_cents as given.