1 package org.apidesign.apifest08.test;
3 import java.util.ArrayList;
4 import java.util.Collection;
5 import junit.framework.TestCase;
6 import org.apidesign.apifest08.currency.Convertor;
7 import org.apidesign.apifest08.currency.CurrencyValue;
8 import org.apidesign.apifest08.currency.ExchangeRateValue;
10 /** There are many currencies around the world and many banks manipulate
11 * with more than one or two at the same time. As banks are usually the
12 * best paying clients, which is true even in case of your Convertor API,
13 * it is reasonable to listen to their requests.
15 * The quest for today is to enhance your existing convertor API to hold
16 * information about many currencies and allow conversions between any of them.
17 * Also, as conversion rates for diferent currencies usually arise from various
18 * bank departments, there is another important need. There is a need to
19 * compose two convertors into one by merging all the information about
20 * currencies they know about.
22 public class Task2Test extends TestCase {
24 public Task2Test(String testName) {
29 protected void setUp() throws Exception {
33 protected void tearDown() throws Exception {
36 // As in Task1Test, keep in mind, that there are three parts
37 // of the whole system:
38 // 1. there is someone who knows the current exchange rate
39 // 2. there is someone who wants to do the conversion
40 // 3. there is the API between 1. and 2. which allows them to communicate
42 // Please backward compatibly enhance your existing API to support following
45 /** Create convertor that understands two currencies, CZK and
46 * SKK. Make 100 SKK == 75 CZK. This is method for the group of users that
47 * knows the exchange rate, and needs to use the API to create objects
48 * with the exchange rate. Anyone shall be ready to call this method without
49 * any other method being called previously. The API itself shall know
50 * nothing about any rates, before this method is called.
52 public static Convertor<Double, String> createTripleConvertor() {
53 // Rates: 1USD = 15CZK
54 // Rates: 1USD = 20SKK
55 // Rates: 75CZK = 100SKK
56 Collection<ExchangeRateValue<Double, String>> exchangeRates =
57 new ArrayList<ExchangeRateValue<Double, String>>();
58 exchangeRates.add(ExchangeRateValue.getExchangeRate(
59 CurrencyValue.getCurrencyValue(1d, "USD"),
60 CurrencyValue.getCurrencyValue(15d, "CZK")));
61 exchangeRates.add(ExchangeRateValue.getExchangeRate(
62 CurrencyValue.getCurrencyValue(1d, "USD"),
63 CurrencyValue.getCurrencyValue(20d, "SKK")));
64 exchangeRates.add(ExchangeRateValue.getExchangeRate(
65 CurrencyValue.getCurrencyValue(75d, "CZK"),
66 CurrencyValue.getCurrencyValue(100d, "SKK")));
67 return Convertor.getConvertorDoubleString(exchangeRates);
70 /** Define convertor that understands three currencies. Use it.
72 public void testConvertorForUSDandCZKandSKK() throws Exception {
73 Convertor<Double, String> c = createTripleConvertor();
75 CurrencyValue<Double, String> result;
76 // convert $5 to CZK using c:
77 // assertEquals("Result is 75 CZK");
78 result = c.convert("CZK", CurrencyValue.getCurrencyValue(5d, "USD"));
79 assertEquals(CurrencyValue.getCurrencyValue(75d, "CZK"), result);
81 // convert $5 to SKK using c:
82 // assertEquals("Result is 100 SKK");
83 result = c.convert("SKK", CurrencyValue.getCurrencyValue(5d, "USD"));
84 assertEquals(CurrencyValue.getCurrencyValue(100d, "SKK"), result);
86 // convert 200SKK to CZK using c:
87 // assertEquals("Result is 150 CZK");
88 result = c.convert("CZK", CurrencyValue.getCurrencyValue(200d, "SKK"));
89 assertEquals(CurrencyValue.getCurrencyValue(150d, "CZK"), result);
91 // convert 200SKK to USK using c:
92 // assertEquals("Result is 10 USD");
93 result = c.convert("USD", CurrencyValue.getCurrencyValue(200d, "SKK"));
94 assertEquals(CurrencyValue.getCurrencyValue(10d, "USD"), result);
97 /** Merge all currency rates of convertor 1 with convertor 2.
98 * Implement this using your API, preferably this method just delegates
99 * into some API method which does the actual work, without requiring
100 * API clients to code anything complex.
102 public static Convertor<Double, String> merge(Convertor<Double, String> one, Convertor<Double, String> two) {
103 return Convertor.mergeConvertorsDoubleString(one, two);
106 /** Join the convertors from previous task, Task1Test and show that it
107 * can be used to do reasonable conversions.
109 public void testConvertorComposition() throws Exception {
110 Convertor<Double, String> c = merge(
111 Task1Test.createCZKtoUSD(),
112 Task1Test.createSKKtoCZK());
114 CurrencyValue<Double, String> result;
115 // convert $5 to CZK using c:
116 // assertEquals("Result is 85 CZK");
117 result = c.convert("CZK", CurrencyValue.getCurrencyValue(5d, "USD"));
118 assertEquals(CurrencyValue.getCurrencyValue(85d, "CZK"), result);
120 // convert $8 to CZK using c:
121 // assertEquals("Result is 136 CZK");
122 result = c.convert("CZK", CurrencyValue.getCurrencyValue(8d, "USD"));
123 assertEquals(CurrencyValue.getCurrencyValue(136d, "CZK"), result);
125 // convert 1003CZK to USD using c:
126 // assertEquals("Result is 59 USD");
127 result = c.convert("USD", CurrencyValue.getCurrencyValue(1003d, "CZK"));
128 assertEquals(CurrencyValue.getCurrencyValue(59d, "USD"), result);
130 // convert 16CZK using c:
131 // assertEquals("Result is 20 SKK");
132 result = c.convert("SKK", CurrencyValue.getCurrencyValue(16d, "CZK"));
133 assertEquals(CurrencyValue.getCurrencyValue(20d, "SKK"), result);
135 // convert 500SKK to CZK using c:
136 // assertEquals("Result is 400 CZK");
137 result = c.convert("CZK", CurrencyValue.getCurrencyValue(500d, "SKK"));
138 assertEquals(CurrencyValue.getCurrencyValue(400d, "CZK"), result);