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package org.apidesign.apifest08.test;
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import java.math.BigDecimal;
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import junit.framework.TestCase;
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import org.apidesign.apifest08.currency.Convertor;
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import org.apidesign.apifest08.currency.ConvertorCurrency;
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import org.apidesign.apifest08.currency.ExchangeRateProvider;
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import org.apidesign.apifest08.currency.IExchangeRateEngine;
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/** The exchange rates are not always the same. They are changing. Day by day,
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* hour by hour, minute by minute. For every bank it is important to always
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* have the actual exchange rate available in the system. That is why let's
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* create a pluggable convertor that will always have up to date value of its
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* exchange rate.
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* <p>
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* The quest for today is to allow 3rd party developer to write a convertor
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* that adjusts its exchange rate everytime it is queried. This convertor is
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* written by independent vendor, the vendor knows only your Convertor API,
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* he does not know how the whole system looks and how the convertor is supposed
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* to be used.
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*/
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public class Task3Test extends TestCase {
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private static ConvertorCurrency currencyCZK = ConvertorCurrency.getInstance("CZK");
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private static ConvertorCurrency currencySKK = ConvertorCurrency.getInstance("SKK");
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private static ConvertorCurrency currencyUSD = ConvertorCurrency.getInstance("USD");
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public Task3Test(String testName) {
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super(testName);
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}
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@Override
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protected void setUp() throws Exception {
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}
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@Override
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protected void tearDown() throws Exception {
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}
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// Backward compatibly enhance your existing API to support following
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// usecases:
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//
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/** Without knowing anything about the surrounding system, write an
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* implementation of convertor that will return different rates everytime
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* it is queried. Convert USD to CZK and vice versa. Start with the rate of
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* 1USD = 16CZK and adjust it in favor of CZK by 0.01 CZK with every query.
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* As soon as you reach 1USD = 15CZK adjust it by 0.01 CZK in favor of USD
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* until you reach 1USD = 16CZK
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*
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* @return new instance of "online" USD and CZK convertor starting with rate 1USD = 16CZK
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*/
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public static Convertor createOnlineCZKUSDConvertor() {
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// initial rate: 1USD = 16CZK
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// 2nd query 1USD = 15.99CZK
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// 3rd query 1USD = 15.98CZK
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// until 1USD = 15.00CZK
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// then 1USD = 15.01CZK
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// then 1USD = 15.02CZK
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// and so on and on up to 1USD = 16CZK
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// and then another round to 15, etc.
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IExchangeRateEngine engine = BouncingExchangeRateEngine.create(
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currencyUSD, new BigDecimal(1),
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currencyCZK,
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new BigDecimal(16),new BigDecimal(15),
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new BigDecimal("-0.01"));
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ExchangeRateProvider exRateProvider = ExchangeRateProvider.createExchangeRateProvider(engine);
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Convertor convertor = Convertor.createConvertor(exRateProvider);
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return convertor;
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}
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public void testFewQueriesForOnlineConvertor() {
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if (Boolean.getBoolean("ignore.failing")) {
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// implement me!
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return;
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}
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Convertor c = createOnlineCZKUSDConvertor();
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doFewQueriesForOnlineConvertor(c);
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}
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static void doFewQueriesForOnlineConvertor(Convertor c) {
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// convert $5 to CZK using c:
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assertEquals("Result is 80 CZK", new BigDecimal("80.00"), c.convertWithReversibleRates(currencyUSD, currencyCZK, new BigDecimal(5)).getConverted());
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// convert $8 to CZK using c:
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assertEquals("Result is 127.92 CZK", new BigDecimal("127.92"), c.convertWithReversibleRates(currencyUSD, currencyCZK, new BigDecimal(8)).getConverted());
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// convert $1 to CZK using c:
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assertEquals("Result is 15.98 CZK", new BigDecimal("15.98"), c.convertWithReversibleRates(currencyUSD, currencyCZK, new BigDecimal(1)).getConverted());
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// convert 15.97CZK to USD using c:
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assertEquals("Result is 15.98 CZK", new BigDecimal("1.00"), c.convertWithReversibleRates(currencyCZK, currencyUSD , new BigDecimal("15.97")).getConverted());
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//fail("Implement me!");
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}
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/** Join the convertors and show they behave sane.
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*/
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public void testOnlineConvertorComposition() throws Exception {
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if (Boolean.getBoolean("ignore.failing")) {
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// implement me!
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return;
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}
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Convertor c = Task2Test.merge(
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createOnlineCZKUSDConvertor(),
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Task1Test.createSKKtoCZK()
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);
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// convert 16CZK to SKK using c:
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assertEquals("Result is 20 CZK", new BigDecimal("20.00"), c.convertWithReversibleRates(currencyCZK, currencySKK , new BigDecimal("16")).getConverted());
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// convert 500SKK to CZK using c:
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assertEquals("Result is 400 CZK", new BigDecimal("400.00"), c.convertWithReversibleRates(currencySKK, currencyCZK , new BigDecimal("500")).getConverted());
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doFewQueriesForOnlineConvertor(c);
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}
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// public void testBouncing() {
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// Convertor c=createOnlineCZKUSDConvertor();
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//
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// IExchangeRateEngine engine = BouncingExchangeRateEngine.create(
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// currencyUSD, new BigDecimal(1),
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// currencyCZK,
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// new BigDecimal("16.00"),new BigDecimal("15.00"),
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// new BigDecimal("-0.01"));
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//
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// for (int i=0;i<300;i++) {
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// System.out.println(engine.getExchangeRate(currencyUSD, currencyCZK).getToValue());
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// }
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// }
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}
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