System Acceptance & Security Testing Center

Purchase 20 pairs of Size 20 → stock must increase by 20 in ledger.

Sell 3 pairs → stock must decrease by 3 in ledger.

Return 1 pair → stock must increase by 1 in ledger.

Exchange Size 20 for Size 21 → Size 20 (+1), Size 21 (-1) in single atomic operation.

Transfer 5 pairs from Warehouse A to B → A decreases by 5, B increases by 5.

Stock adjustment → ledger and audit log must both record difference and reason.

Attempt to sell unavailable SKU → system must follow configured negative-stock policy.

Generate stock valuation → result must match inventory ledger balances.

Verify that exactly 1 owner account exists with full administrative privileges.

Password hashes must be salted and correctly validated with Argon2id format.

Failed login returns generic 'Invalid user ID or password' without exposing account existence.

First-time login locks access and routes owner to /first-login with zero business data leaked.

5 repeated failed logins trigger temporary account lockout duration.

User logout destroys the active session and logs audit trail record.

Authenticated owner has unrestricted access to all 12 ERP and POS modules.

Audit database records: zero plaintext passwords exist in state or storage.

All stock movements, logins, and setting updates create permanent immutable audit logs.

Void and reversal workflows used instead of hard record deletions.