# HG changeset patch
# User japod@localhost
# Date 1222768772 -7200
# Node ID 83e731257bdc774ed9892f7b639ab8506140006c
# Parent  37c9921c653e4801c1696ba1a41af0111ada8424
updating solution 07 to 1.5

diff -r 37c9921c653e -r 83e731257bdc task1/solution07/src/org/apidesign/apifest08/currency/Convertor.java
--- a/task1/solution07/src/org/apidesign/apifest08/currency/Convertor.java	Tue Sep 30 11:50:09 2008 +0200
+++ b/task1/solution07/src/org/apidesign/apifest08/currency/Convertor.java	Tue Sep 30 11:59:32 2008 +0200
@@ -20,7 +20,7 @@
      * When the need comes to extend the semantics, one subclasses the ConversionRequest and/or ConversionResult classes.
      * <p>
      * This method can be called as many times as you like.
-     * A {@link Convertor} shall be considered immutable.
+     * A {@link Convertor} shall be considered immutable wrt calls to {@link #convert(org.apidesign.apifest08.currency.Convertor.ConversionRequest).
      * This method of a single {@link Convertor} can be called from many threads concurrently.
      * @param req the conversion request; mustn't be null
      * @return the result of carrying out the conversion request; never null
diff -r 37c9921c653e -r 83e731257bdc task1/solution07/test/org/apidesign/apifest08/test/Task1Test.java
--- a/task1/solution07/test/org/apidesign/apifest08/test/Task1Test.java	Tue Sep 30 11:50:09 2008 +0200
+++ b/task1/solution07/test/org/apidesign/apifest08/test/Task1Test.java	Tue Sep 30 11:59:32 2008 +0200
@@ -26,12 +26,24 @@
     protected void tearDown() throws Exception {
     }
 
+    //
+    // Imagine that there are three parts of the whole system:
+    // 1. there is someone who knows the current exchange rate
+    // 2. there is someone who wants to do the conversion
+    // 3. there is the API between 1. and 2. which allows them to communicate
+    // Please design such API
+    //
+
     protected static final Currency CZK = Currency.getInstance( "CZK" );
     protected static final Currency SKK = Currency.getInstance( "SKK" );
     protected static final Currency USD = Currency.getInstance( "USD" );
     
     /** Create convertor that understands two currencies, CZK and
      *  USD. Make 1 USD == 17 CZK.
+     *  USD. Make 1 USD == 17 CZK. This is a method provided for #1 group -
+     *  e.g. those that know the exchange rate. They somehow need to create
+     *  the objects from the API and tell them the exchange rate. The API itself
+     *  knows nothing about any rates, before the createCZKtoUSD method is called.
      *
      * Creation of the convertor shall not require subclassing of any class
      * or interface on the client side.
@@ -48,7 +60,11 @@
     }
 
     /** Create convertor that understands two currencies, CZK and
-     *  SKK. Make 100 SKK == 80 CZK.
+     *  SKK. Make 100 SKK == 80 CZK. Again this is method for the #1 group -
+     *  it knows the exchange rate, and needs to use the API to create objects
+     *  with the exchange rate. Anyone shall be ready to call this method without
+     *  any other method being called previously. The API itself shall know
+     *  nothing about any rates, before this method is called.
      *
      * Creation of the convertor shall not require subclassing of any class
      * or interface on the client side.
@@ -64,6 +80,13 @@
         return new ContractImposingDelegatingConvertor( convertor ).test();
     }
 
+    //
+    // now the methods for group #2 follow:
+    // this group knows nothing about exchange rates, but knows how to use
+    // the API to do conversions. It somehow (by calling one of the factory
+    // methods) gets objects from the API and uses them to do the conversions.
+    //
+
     /** Use the convertor from <code>createCZKtoUSD</code> method and do few conversions
      * with it.
      */
@@ -118,5 +141,37 @@
         assertEquals( CZK, a2.getCurrency() );
     }
 
+    /** Verify that the CZK to USD convertor knows nothing about SKK.
+    */
+    public void testCannotConvertToSKKwithCZKUSDConvertor() throws Exception {
+        final Convertor c = createCZKtoUSD();
+        
+        // convert $5 to SKK, the API shall say this is not possible
+        final Convertor.ConversionResult r1 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 5, USD ), SKK ) );
+        final MonetaryAmount a1 = r1.getNetAmount();
+        assertNull( a1 );
+
+        // convert 500 SKK to CZK, the API shall say this is not possible
+        final Convertor.ConversionResult r2 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 5, SKK ), CZK ) );
+        final MonetaryAmount a2 = r2.getNetAmount();
+        assertNull( a2 );
+    }
+
+    /** Verify that the CZK to SKK convertor knows nothing about USD.
+    */
+    public void testCannotConvertToUSDwithCZKSKKConvertor() throws Exception {
+        final Convertor c = createSKKtoCZK();
+        
+        // convert $5 to SKK, the API shall say this is not possible
+        final Convertor.ConversionResult r1 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 5, USD ), SKK ) );
+        final MonetaryAmount a1 = r1.getNetAmount();
+        assertNull( a1 );
+        
+        // convert 500 CZK to USD, the API shall say this is not possible
+        final Convertor.ConversionResult r2 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 5, CZK ), USD ) );
+        final MonetaryAmount a2 = r2.getNetAmount();
+        assertNull( a2 );
+    }
+
 }