## mark a section (Learn more)

def test_change_quantity_for_product @cart = carts(:first) @item = @cart.line_items[0] assert_no_difference @cart.line_items, :count do assert_difference @item, :quantity, 1, true do assert_difference @cart, :total_in_cents, @item.price_in_cents do @cart.update_products(@item.product.id => 1) end end end assert_total end

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