1.1 --- a/task1/solution07/src/org/apidesign/apifest08/currency/Convertor.java	Tue Sep 30 11:50:09 2008 +0200
     1.2 +++ b/task1/solution07/src/org/apidesign/apifest08/currency/Convertor.java	Tue Sep 30 11:59:32 2008 +0200
     1.3 @@ -20,7 +20,7 @@
     1.4       * When the need comes to extend the semantics, one subclasses the ConversionRequest and/or ConversionResult classes.
     1.5       * <p>
     1.6       * This method can be called as many times as you like.
     1.7 -     * A {@link Convertor} shall be considered immutable.
     1.8 +     * A {@link Convertor} shall be considered immutable wrt calls to {@link #convert(org.apidesign.apifest08.currency.Convertor.ConversionRequest).
     1.9       * This method of a single {@link Convertor} can be called from many threads concurrently.
    1.10       * @param req the conversion request; mustn't be null
    1.11       * @return the result of carrying out the conversion request; never null

     2.1 --- a/task1/solution07/test/org/apidesign/apifest08/test/Task1Test.java	Tue Sep 30 11:50:09 2008 +0200
     2.2 +++ b/task1/solution07/test/org/apidesign/apifest08/test/Task1Test.java	Tue Sep 30 11:59:32 2008 +0200
     2.3 @@ -26,12 +26,24 @@
     2.4      protected void tearDown() throws Exception {
     2.5      }
     2.6  
     2.7 +    //
     2.8 +    // Imagine that there are three parts of the whole system:
     2.9 +    // 1. there is someone who knows the current exchange rate
    2.10 +    // 2. there is someone who wants to do the conversion
    2.11 +    // 3. there is the API between 1. and 2. which allows them to communicate
    2.12 +    // Please design such API
    2.13 +    //
    2.14 +
    2.15      protected static final Currency CZK = Currency.getInstance( "CZK" );
    2.16      protected static final Currency SKK = Currency.getInstance( "SKK" );
    2.17      protected static final Currency USD = Currency.getInstance( "USD" );
    2.18      
    2.19      /** Create convertor that understands two currencies, CZK and
    2.20       *  USD. Make 1 USD == 17 CZK.
    2.21 +     *  USD. Make 1 USD == 17 CZK. This is a method provided for #1 group -
    2.22 +     *  e.g. those that know the exchange rate. They somehow need to create
    2.23 +     *  the objects from the API and tell them the exchange rate. The API itself
    2.24 +     *  knows nothing about any rates, before the createCZKtoUSD method is called.
    2.25       *
    2.26       * Creation of the convertor shall not require subclassing of any class
    2.27       * or interface on the client side.
    2.28 @@ -48,7 +60,11 @@
    2.29      }
    2.30  
    2.31      /** Create convertor that understands two currencies, CZK and
    2.32 -     *  SKK. Make 100 SKK == 80 CZK.
    2.33 +     *  SKK. Make 100 SKK == 80 CZK. Again this is method for the #1 group -
    2.34 +     *  it knows the exchange rate, and needs to use the API to create objects
    2.35 +     *  with the exchange rate. Anyone shall be ready to call this method without
    2.36 +     *  any other method being called previously. The API itself shall know
    2.37 +     *  nothing about any rates, before this method is called.
    2.38       *
    2.39       * Creation of the convertor shall not require subclassing of any class
    2.40       * or interface on the client side.
    2.41 @@ -64,6 +80,13 @@
    2.42          return new ContractImposingDelegatingConvertor( convertor ).test();
    2.43      }
    2.44  
    2.45 +    //
    2.46 +    // now the methods for group #2 follow:
    2.47 +    // this group knows nothing about exchange rates, but knows how to use
    2.48 +    // the API to do conversions. It somehow (by calling one of the factory
    2.49 +    // methods) gets objects from the API and uses them to do the conversions.
    2.50 +    //
    2.51 +
    2.52      /** Use the convertor from <code>createCZKtoUSD</code> method and do few conversions
    2.53       * with it.
    2.54       */
    2.55 @@ -118,5 +141,37 @@
    2.56          assertEquals( CZK, a2.getCurrency() );
    2.57      }
    2.58  
    2.59 +    /** Verify that the CZK to USD convertor knows nothing about SKK.
    2.60 +    */
    2.61 +    public void testCannotConvertToSKKwithCZKUSDConvertor() throws Exception {
    2.62 +        final Convertor c = createCZKtoUSD();
    2.63 +        
    2.64 +        // convert $5 to SKK, the API shall say this is not possible
    2.65 +        final Convertor.ConversionResult r1 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 5, USD ), SKK ) );
    2.66 +        final MonetaryAmount a1 = r1.getNetAmount();
    2.67 +        assertNull( a1 );
    2.68 +
    2.69 +        // convert 500 SKK to CZK, the API shall say this is not possible
    2.70 +        final Convertor.ConversionResult r2 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 5, SKK ), CZK ) );
    2.71 +        final MonetaryAmount a2 = r2.getNetAmount();
    2.72 +        assertNull( a2 );
    2.73 +    }
    2.74 +
    2.75 +    /** Verify that the CZK to SKK convertor knows nothing about USD.
    2.76 +    */
    2.77 +    public void testCannotConvertToUSDwithCZKSKKConvertor() throws Exception {
    2.78 +        final Convertor c = createSKKtoCZK();
    2.79 +        
    2.80 +        // convert $5 to SKK, the API shall say this is not possible
    2.81 +        final Convertor.ConversionResult r1 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 5, USD ), SKK ) );
    2.82 +        final MonetaryAmount a1 = r1.getNetAmount();
    2.83 +        assertNull( a1 );
    2.84 +        
    2.85 +        // convert 500 CZK to USD, the API shall say this is not possible
    2.86 +        final Convertor.ConversionResult r2 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 5, CZK ), USD ) );
    2.87 +        final MonetaryAmount a2 = r2.getNetAmount();
    2.88 +        assertNull( a2 );
    2.89 +    }
    2.90 +
    2.91  }
    2.92