# Spot the bug: Ruby on Rails

> One snippet. Find the bug, or prove there isn't one.

Daily challenge: 2026-08-19 (UTC) · Mid-Level

```ruby
class CartCalculator
  def total_with_discount(items, discount_rate)
    subtotal = items.sum(&:price)
    discount = subtotal * discount_rate
    subtotal - discount
  end
end
```

## Your verdict

- Security flaw
- Logic bug
- Code style
- No issue

One attempt per day. The answer shows up right after.

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