jaroslav@43: package org.apidesign.apifest08.test;
jaroslav@43: 
jaroslav@43: import junit.framework.TestCase;
jaroslav@43: import org.apidesign.apifest08.currency.Convertor;
jaroslav@43: 
jaroslav@43: /** The exchange rates are not always the same. They are changing. Day by day,
jaroslav@43:  * hour by hour, minute by minute. For every bank it is important to always
jaroslav@43:  * have the actual exchange rate available in the system. That is why let's
jaroslav@43:  * create a pluggable convertor that will always have up to date value of its
jaroslav@43:  * exchange rate.
jaroslav@43:  * <p>
jaroslav@43:  * The quest for today is to allow 3rd party developer to write a convertor
jaroslav@43:  * that adjusts its exchange rate everytime it is queried. This convertor is
jaroslav@43:  * written by independent vendor, the vendor knows only your Convertor API,
jaroslav@43:  * he does not know how the whole system looks and how the convertor is supposed
jaroslav@43:  * to be used.
jaroslav@43:  */
jaroslav@43: public class Task3Test extends TestCase {
jaroslav@43:     public Task3Test(String testName) {
jaroslav@43:         super(testName);
jaroslav@43:     }
jaroslav@43: 
jaroslav@43:     @Override
jaroslav@43:     protected void setUp() throws Exception {
jaroslav@43:     }
jaroslav@43: 
jaroslav@43:     @Override
jaroslav@43:     protected void tearDown() throws Exception {
jaroslav@43:     }
jaroslav@43: 
jaroslav@43:     // Backward compatibly enhance your existing API to support following
jaroslav@43:     // usecases:
jaroslav@43:     //
jaroslav@43: 
jaroslav@43: 
jaroslav@43:     /** Without knowing anything about the surrounding system, write an
jaroslav@43:      * implementation of convertor that will return different rates everytime
jaroslav@43:      * it is queried. Convert USD to CZK and vice versa. Start with the rate of
jaroslav@43:      * 1USD = 16CZK and adjust it in favor of CZK by 0.01 CZK with every query.
jaroslav@43:      * As soon as you reach 1USD = 15CZK adjust it by 0.01 CZK in favor of USD
jaroslav@43:      * until you reach 1USD = 16CZK
jaroslav@43:      *
jaroslav@43:      * @return new instance of "online" USD and CZK convertor starting with rate 1USD = 16CZK
jaroslav@43:      */
jaroslav@43:     public static Convertor createOnlineCZKUSDConvertor() {
jaroslav@43:         // initial rate: 1USD = 16CZK
jaroslav@43:         // 2nd query 1USD = 15.99CZK
jaroslav@43:         // 3rd query 1USD = 15.98CZK
jaroslav@43:         // until 1USD = 15.00CZK
jaroslav@43:         // then 1USD = 15.01CZK
jaroslav@43:         // then 1USD = 15.02CZK
jaroslav@43:         // and so on and on up to 1USD = 16CZK
jaroslav@43:         // and then another round to 15, etc.
jaroslav@43:         return null;
jaroslav@43:     }
jaroslav@43: 
jaroslav@43:     public void testFewQueriesForOnlineConvertor() {
jaroslav@43:         Convertor c = createOnlineCZKUSDConvertor();
jaroslav@43:         doFewQueriesForOnlineConvertor(c);
jaroslav@43:     }
jaroslav@43: 
jaroslav@43:     static void doFewQueriesForOnlineConvertor(Convertor c) {
jaroslav@43:         // convert $5 to CZK using c:
jaroslav@43:         //assertEquals("Result is 80 CZK");
jaroslav@43: 
jaroslav@43:         // convert $8 to CZK using c:
jaroslav@43:         //assertEquals("Result is 127.92 CZK");
jaroslav@43: 
jaroslav@43:         // convert $1 to CZK using c:
jaroslav@43:         //assertEquals("Result is 15.98 CZK");
jaroslav@43: 
jaroslav@43:         // convert 15.97CZK to USD using c:
jaroslav@43:         //assertEquals("Result is 1$");
jaroslav@43: 
jaroslav@43:         fail("Implement me!");
jaroslav@43:     }
jaroslav@43: 
jaroslav@43:     /** Join the convertors and show they behave sane.
jaroslav@43:      */
jaroslav@43:     public void testOnlineConvertorComposition() throws Exception {
jaroslav@43:         Convertor c = Task2Test.merge(
jaroslav@43:             createOnlineCZKUSDConvertor(),
jaroslav@43:             Task1Test.createSKKtoCZK()
jaroslav@43:         );
jaroslav@43: 
jaroslav@43:         // convert 16CZK to SKK using c:
jaroslav@43:         // assertEquals("Result is 20 SKK");
jaroslav@43: 
jaroslav@43:         // convert 500SKK to CZK using c:
jaroslav@43:         // assertEquals("Result is 400 CZK");
jaroslav@43: 
jaroslav@43:         doFewQueriesForOnlineConvertor(c);
jaroslav@43:     }
jaroslav@43: }