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| def assert_equal(expected, actual) | |
| print expected == actual ? "." : "Expected #{expected.inspect} but got #{actual.inspect}\n" | |
| end | |
| class SummingRule | |
| def initialize(item, price) | |
| @item = item | |
| @price = price | |
| end | |
| def apply(basket) | |
| basket.count(@item) * @price | |
| end | |
| end | |
| class DiscountRule | |
| def initialize(item, count, discount) | |
| @item = item | |
| @count = count | |
| @discount = discount | |
| end | |
| def apply(basket) | |
| (basket.count(@item) / @count) * -@discount | |
| end | |
| end | |
| class Checkout | |
| def initialize | |
| @basket = [] | |
| @rules = [ | |
| SummingRule.new("A", 50), | |
| SummingRule.new("B", 30), | |
| DiscountRule.new("A", 3, 20), | |
| DiscountRule.new("B", 2, 15) | |
| ] | |
| end | |
| def total | |
| total = 0 | |
| @rules.each do |rule| | |
| total += rule.apply(@basket) | |
| end | |
| total | |
| end | |
| def scan(item) | |
| @basket.push(item) | |
| end | |
| end | |
| checkout = Checkout.new | |
| assert_equal(0, checkout.total) | |
| checkout.scan("A") | |
| assert_equal(50, checkout.total) | |
| checkout.scan("B") | |
| assert_equal(80, checkout.total) | |
| checkout = Checkout.new | |
| checkout.scan("A") | |
| checkout.scan("A") | |
| checkout.scan("A") | |
| assert_equal(130, checkout.total) | |
| checkout = Checkout.new | |
| checkout.scan("B") | |
| checkout.scan("B") | |
| assert_equal(45, checkout.total) | |
| puts |
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