# HG changeset patch
# User Jaroslav Tulach <jaroslav.tulach@apidesign.org>
# Date 1223761006 -7200
# Node ID a92eff6b426fff2ac04aa3db67ba33511f210117
# Parent  c1d43bc1e9c03a8185c9291076ded5b6f068b53b
Quest for task4

diff -r c1d43bc1e9c0 -r a92eff6b426f currency/test/org/apidesign/apifest08/test/Task4Test.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/currency/test/org/apidesign/apifest08/test/Task4Test.java	Sat Oct 11 23:36:46 2008 +0200
@@ -0,0 +1,132 @@
+package org.apidesign.apifest08.test;
+
+import java.util.Date;
+import junit.framework.TestCase;
+import org.apidesign.apifest08.currency.Convertor;
+
+/** The exchange rates are not always the same. They are changing. However
+ * as in order to predict the future, one needs to understand own past. That is
+ * why it is important to know the exchange rate as it was at any time during
+ * the past.
+ * <p>
+ * Today's quest is to enhance the convertor API to deal with dates.
+ * One shall be able to convert a currency at any date. Each currencies rate shall
+ * be associated with a range between two Date objects. In order
+ * to keep compatibility with old API that knew nothing about dates, the
+ * rates associated then are applicable "for eternity". Any use of existing
+ * convert methods that do not accept a Date argument, uses the current
+ * System.currentTimeMillis() as default date.
+ */
+public class Task4Test extends TestCase {
+    public Task4Test(String testName) {
+        super(testName);
+    }
+
+    @Override
+    protected void setUp() throws Exception {
+    }
+
+    @Override
+    protected void tearDown() throws Exception {
+    }
+
+    // Backward compatibly enhance your existing API to support following
+    // usecases:
+    //
+
+    /** Takes a convertor with any rates associated and creates new convertor
+     * that returns the same values as the old one for time between from to till.
+     * Otherwise it returns no results. This is just a helper method that
+     * shall call some real one in the API.
+     * 
+     * @param old existing convertor
+     * @param from initial date (inclusive)
+     * @param till final date (exclusive)
+     * @return new convertor
+     */
+    public static Convertor limitTo(Convertor old, Date from, Date till) {
+        return null;
+    }
+
+
+    public void testCompositionOfLimitedConvertors() throws Exception {
+        if (Boolean.getBoolean("ignore.failing")) {
+            // implement me! then delete this if statement
+            return;
+        }
+
+        Date d1 = null; // 2008-10-01 0:00 GMT
+        Date d2 = null; // 2008-10-02 0:00 GMT
+        Date d3 = null; // 2008-10-03 0:00 GMT
+        
+        Convertor c = Task2Test.merge(
+            limitTo(Task1Test.createCZKtoUSD(), d1, d2),
+            limitTo(Task1Test.createSKKtoCZK(), d2, d3)
+        );
+
+        // convert $5 to CZK using c:
+        // cannot convert as no rate is applicable to current date
+
+        // convert $8 to CZK using c:
+        // cannot convert as no rate is applicable to current date
+
+        // convert 1003CZK to USD using c:
+        // cannot convert as no rate is applicable to current date
+
+        // convert 16CZK using c:
+        // cannot convert as no rate is applicable to current date
+
+        // convert 500SKK to CZK using c:
+        // cannot convert as no rate is applicable to current date
+
+        // convert $5 to CZK using c at 2008-10-01 6:00 GMT:
+        // assertEquals("Result is 85 CZK");
+
+        // convert $8 to CZK using c at 2008-10-01 6:00 GMT:
+        // assertEquals("Result is 136 CZK");
+
+        // convert 1003CZK to USD using c at 2008-10-01 6:00 GMT:
+        // assertEquals("Result is 59 USD");
+
+        // convert 16CZK using c at 2008-10-02 9:00 GMT:
+        // assertEquals("Result is 20 SKK");
+
+        // convert 500SKK to CZK using c at 2008-10-02 9:00 GMT:
+        // assertEquals("Result is 400 CZK");
+
+        // convert 500SKK to CZK using c at 2008-10-01 6:00 GMT:
+        // cannot convert as no rate is applicable to current date
+    }
+
+    /** Create convertor that understands two currencies, CZK and
+     *  SKK. Make 100 SKK == 90 CZK.
+     *
+     * @return prepared convertor ready for converting SKK to CZK and CZK to SKK
+     */
+    public static Convertor createSKKtoCZK2() {
+        return null;
+    }
+
+    public void testDateConvetorWithTwoDifferentRates() throws Exception {
+        if (Boolean.getBoolean("ignore.failing")) {
+            // implement me! then delete this if statement
+            return;
+        }
+
+        Date d1 = null; // 2008-10-01 0:00 GMT
+        Date d2 = null; // 2008-10-02 0:00 GMT
+        Date d3 = null; // 2008-10-03 0:00 GMT
+
+        Convertor c = Task2Test.merge(
+            limitTo(createSKKtoCZK2(), d1, d2),
+            limitTo(Task1Test.createSKKtoCZK(), d2, d3)
+        );
+
+        // convert 500SKK to CZK using c at 2008-10-02 9:00 GMT:
+        // assertEquals("Result is 400 CZK");
+
+        // convert 500SKK to CZK using c at 2008-10-01 6:00 GMT:
+        // assertEquals("Result is 450 CZK");
+    }
+
+}