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package org.apidesign.apifest08.test;
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japod@6
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japod@6
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import java.util.Currency;
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japod@6
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import junit.framework.TestCase;
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japod@6
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japod@6
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import org.apidesign.apifest08.currency.Convertor;
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japod@20
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import org.apidesign.apifest08.currency.exceptions.InvalidCurrencyException;
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import org.apidesign.apifest08.currency.exceptions.UnknownConvertorException;
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japod@6
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/**
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* Finish the Convertor API, and then write bodies of methods inside of this class to match the given tasks. To fullfil
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japod@6
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* your task, use the API define in the <code>org.apidesign.apifest08.currency</code> package. Do not you reflection, or
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japod@6
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* other hacks as your code shall run without any runtime permissions.
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*/
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japod@6
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public class Task1Test extends TestCase {
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public Task1Test(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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japod@20
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//
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// Imagine that there are three parts of the whole system:
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// 1. there is someone who knows the current exchange rate
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// 2. there is someone who wants to do the conversion
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// 3. there is the API between 1. and 2. which allows them to communicate
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// Please design such API
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//
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japod@20
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japod@6
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/**
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* Create convertor that understands two currencies, CZK and USD. Make 1 USD == 17 CZK. This is a method provided for
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* #1 group - e.g. those that know the exchange rate. They somehow need to create the objects from the API and tell
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* them the exchange rate. The API itself knows nothing about any rates, before the createCZKtoUSD method is called.
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* Creation of the convertor shall not require subclassing of any class or interface on the client side.
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* @return prepared convertor ready for converting USD to CZK and CZK to USD
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*/
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public static Convertor createCZKtoUSD() {
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// set exchange rates
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Convertor.setConvertorRates(Currency.getInstance("USD"), Currency.getInstance("CZK"), 17d, 1d);
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// create new instance
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Convertor convertor = null;
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try {
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convertor = Convertor.getConvertorInstance(Currency.getInstance("USD"), Currency.getInstance("CZK"));
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} catch (UnknownConvertorException e) {
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e.printStackTrace();
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}
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return convertor;
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}
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/**
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* Create convertor that understands two currencies, CZK and SKK. Make 100 SKK == 80 CZK. Again this is method for the
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* #1 group - it knows the exchange rate, and needs to use the API to create objects with the exchange rate. Anyone
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* shall be ready to call this method without any other method being called previously. The API itself shall know
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* nothing about any rates, before this method is called. Creation of the convertor shall not require subclassing of
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* any class or interface on the client side.
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* @return prepared convertor ready for converting SKK to CZK and CZK to SKK
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*/
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public static Convertor createSKKtoCZK() {
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// set exchange rates
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Convertor.setConvertorRates(Currency.getInstance("SKK"), Currency.getInstance("CZK"), 80d, 100d);
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// create new instance
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Convertor convertor = null;
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try {
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convertor = Convertor.getConvertorInstance(Currency.getInstance("SKK"), Currency.getInstance("CZK"));
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} catch (UnknownConvertorException e) {
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e.printStackTrace();
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}
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return convertor;
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}
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//
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// now the methods for group #2 follow:
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// this group knows nothing about exchange rates, but knows how to use
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// the API to do conversions. It somehow (by calling one of the factory
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// methods) gets objects from the API and uses them to do the conversions.
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//
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/**
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* Use the convertor from <code>createCZKtoUSD</code> method and do few conversions with it.
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*/
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public void testCurrencyCZKUSD() throws Exception {
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Convertor c = createCZKtoUSD();
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// convert $5 to CZK using c:
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double result = c.convert(5, Currency.getInstance("USD"), Currency.getInstance("CZK"));
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assertEquals("Result is not 85 CZK", 85.0, result);
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// convert $8 to CZK
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result = c.convert(8, Currency.getInstance("USD"), Currency.getInstance("CZK"));
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assertEquals("Result is not 136 CZK", 136.0, result);
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// convert 1003CZK to USD
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result = c.convert(1003, Currency.getInstance("CZK"), Currency.getInstance("USD"));
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assertEquals("Result is not 59 USD", 59.0, result);
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}
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/**
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* Use the convertor from <code>createSKKtoCZK</code> method and do few conversions with it.
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*/
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public void testCurrencySKKCZK() throws Exception {
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Convertor c = createSKKtoCZK();
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// convert 16CZK using c:
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double result = c.convert(16, Currency.getInstance("CZK"), Currency.getInstance("SKK"));
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assertEquals("Result is not 20 SKK", 20.0, result);
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// convert 500SKK to CZK
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result = c.convert(500, Currency.getInstance("SKK"), Currency.getInstance("CZK"));
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assertEquals("Result is not 400 CZK", 400.0, result);
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}
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/**
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* Verify that the CZK to USD convertor knows nothing about SKK.
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*/
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public void testCannotConvertToSKKwithCZKUSDConvertor() throws Exception {
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Convertor c = createCZKtoUSD();
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boolean exceptionThrown = false;
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// convert $5 to SKK, the API shall say this is not possible
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try {
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c.convert(5, Currency.getInstance("USD"), Currency.getInstance("SKK"));
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exceptionThrown = false;
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} catch (InvalidCurrencyException e) {
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exceptionThrown = true;
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}
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assertEquals("It should be impossible to convert to SKK with USD->CZK convertor", true, exceptionThrown);
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// convert 500 SKK to CZK, the API shall say this is not possible
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try {
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c.convert(500, Currency.getInstance("SKK"), Currency.getInstance("CZK"));
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exceptionThrown = false;
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} catch (InvalidCurrencyException e) {
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exceptionThrown = true;
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}
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assertEquals("It should be impossible to convert from SKK with USD->CZK convertor", true, exceptionThrown);
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}
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/**
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* Verify that the CZK to SKK convertor knows nothing about USD.
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*/
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public void testCannotConvertToSKKwithSKKCZKConvertor() throws Exception {
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Convertor c = createSKKtoCZK();
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boolean exceptionThrown = false;
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// convert $5 to SKK, the API shall say this is not possible
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try {
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c.convert(5, Currency.getInstance("USD"), Currency.getInstance("SKK"));
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exceptionThrown = false;
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} catch (InvalidCurrencyException e) {
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exceptionThrown = true;
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}
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assertEquals("It should be impossible to convert form USD with SKK->CZK convertor", true, exceptionThrown);
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// convert 500 CZK to USD, the API shall say this is not possible
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try {
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c.convert(500, Currency.getInstance("CZK"), Currency.getInstance("USD"));
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exceptionThrown = false;
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} catch (InvalidCurrencyException e) {
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exceptionThrown = true;
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}
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assertEquals("It should be impossible to convert to USD with SKK->CZK convertor", true, exceptionThrown);
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}
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}
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