src/test/java/wtf/metio/reguloj/shoppingcart/ShoppingCartTest.java

   1 /*
   2  * This file is part of reguloj. It is subject to the license terms in the LICENSE file found in the top-level
   3  * directory of this distribution and at http://creativecommons.org/publicdomain/zero/1.0/. No part of reguloj,
   4  * including this file, may be copied, modified, propagated, or distributed except according to the terms contained
   5  * in the LICENSE file.
   6  */
   7
   8 package wtf.metio.reguloj.shoppingcart;
   9
  10 import java.util.ArrayList;
  11 import java.util.Collection;
  12 import java.util.List;
  13 import org.junit.jupiter.api.Assertions;
  14 import org.junit.jupiter.api.BeforeEach;
  15 import org.junit.jupiter.api.Test;
  16 import wtf.metio.reguloj.Rule;
  17 import wtf.metio.reguloj.RuleEngine;
  18
  19 class ShoppingCartTest {
  20
  21   private static final Product TEST_PRODUCT = new Product("xPhone 37");
  22
  23   private Collection<Rule<Cart>> rules;
  24   private RuleEngine<Cart> ruleEngine;
  25
  26   @BeforeEach
  27   void setUp() {
  28     final var standardPrice = Rule.<Cart>called("single purchase uses standard price")
  29         .when(cart -> true) // always fires thus can be used as a fallback
  30         .then(cart -> cart.prices().add(new Price(TEST_PRODUCT, 100)));
  31     final var reducedPrice = Rule.<Cart>called("multiple purchases get reduced price")
  32         .when(cart -> cart.topic().size() > 1) // only fires for multiple products
  33         .then(cart -> cart.prices().add(new Price(TEST_PRODUCT, 75 * cart.topic().size())));
  34     // the order is important here, so we use a List
  35     rules = List.of(reducedPrice, standardPrice);
  36     // since we control the order, we can only run the first rule that fires
  37     ruleEngine = RuleEngine.firstWins();
  38   }
  39
  40   @Test
  41   void shouldCalculatePrice() {
  42     // given
  43     final var cart = new Cart(List.of(TEST_PRODUCT), new ArrayList<>());
  44
  45     // when
  46     ruleEngine.infer(rules, cart);
  47
  48     // then
  49     assertPrice(cart, 100);
  50   }
  51
  52   @Test
  53   void shouldCalculatePriceForMultipleProducts() {
  54     // given
  55     final var cart = new Cart(List.of(TEST_PRODUCT, TEST_PRODUCT), new ArrayList<>());
  56
  57     // when
  58     ruleEngine.infer(rules, cart);
  59
  60     // then
  61     assertPrice(cart, 150);
  62   }
  63
  64   private void assertPrice(final Cart cart, final int expectedPrice) {
  65     Assertions.assertAll("prices",
  66         () -> Assertions.assertNotNull(cart.prices()),
  67         () -> Assertions.assertEquals(1, cart.prices().size()),
  68         () -> Assertions.assertEquals(expectedPrice, cart.prices().get(0).price())
  69     );
  70   }
  71
  72 }