Using a Custom System Under Development (SUD)

Why ?

The system under development is a bridge between your Fixtures and the system your testing.
If you want to change the way GreenPepper is finding/instanciating your fixtures, or if you need to hook the document execution then you can define a Custom System Under Development.

Using custom types

All the examples in the documents are in strings, but fixtures want to process and return other data types.

GreenPepper provides a mechanism to help conversion from String to other data types and back again.

so an example that look likes

Will match a class with the following method

public class SomeFixture {
   public SomeFixture(Ammount ammount) {...}

   public setColor(RGB color) ...
   public someBool(boolean yesNo)..
   public Ratio answer()...
}

Lets look at how GreenPepper will match these.

Converters

Converters are class implementing the interface com.greenpepper.converter.TypeConverter in java or GreenPepper.Converters.ITypeConverter in C#

public interface TypeConverter
{
    boolean canConvertTo( Class type );

    Object parse( String value, Class type );

    String toString( Object value );
}

namespace GreenPepper.Converters
{
    public interface ITypeConverter
    {
        bool CanConvertTo(Type type);

        object ValueOf(string value, Type type);

        string ToString(object value);
    }
}

GreenPepper provides out of the box type converters for the following types

• Integer
• Long
• Float
• Double
• Date
• Boolean
• Array
• String

or their simpler form int, long ...

(order is important see adding a new type converter below)

The ArrayConverter calls recursively the other converters depending on the component type the array holds.

Adding a new type converter

The com.greenpepper.GreenPepper class provides a method to add your own type converter

public static void register( TypeConverter converter)

public static void Register( ITypeConverter converter)

The better place to register your custom type is in a custom system under developement :

public static class CustomSystemUnderDevelopment extends DefaultSystemUnderDevelopment
    {
        public CustomSystemUnderDevelopment( String... params )
        {
           GreenPepper.register(new MyCustomTypeConverter());
        }
    }

The converters are always check in an LIFO manners. If two converters can process a data type the last one that has been register will be used. That way, you can provides your own converters in place of the standard GreenPepper converters. 

Self conversion

Instead of registering a TypeConverter, you can uses self converting types.

Self converting type implies that you add a static parse method to your class.

public static T parse(String val);
// And then to revert back to a string,
public static String toString(T value)

public static T ValueOf(string text)
// And then to revert back to a string,
public static String ToString(T value)

Your class does not have to provides both of them.

Rules of conversion 

From example to fixture

1. First GreenPepper  will look for a registered TypeConverter that can handles the type.
2. Second GreenPepper will verify if the type is can self convert (ie public static T parse(String) or public static T ValueOf(string))
3. An UnsupportedOperationException will be thrown

From fixture return value to String

1. First GreenPepper  will look for a registered TypeConverter that can handles the type. 
2. Second GreenPepper will verify if the type is can self revert (ie public static String toString(T) or public static T ToString(string))
3. Use the toString() or ToString() method on the data itself.

Changing how GreenPepper is finding your Fixtures

public static class CustomSystemUnderDevelopment extends DefaultSystemUnderDevelopment  {
        public CustomSystemUnderDevelopment( String... params )
        {
           super.addImport("com.mycompany.fixtures");
           super.addImport("com.mycompany.specials.fixtures");
        }
}

Changing Fixture instanciation mechanism (Spring example)

package com.greenpepper.extensions.spring;

import ...;

public class SpringSystemUnderDevelopment extends DefaultSystemUnderDevelopment
{
    private BeanFactory beanFactory;

    public SpringSystemUnderDevelopment(String... applicationCtxes)
    {
        this.beanFactory = new GreenPepperXMLAplicationContext(applicationCtxes).getBeanFactory();
    }

    public SpringSystemUnderDevelopment(BeanFactory beanFactory)
    {
        this.beanFactory = beanFactory;
    }

    @Override
    public Fixture getFixture(String fixtureName, String... params) throws Throwable
    {
        Fixture fixture;
        if (params.length != 0)
        {
            fixture = super.getFixture(fixtureName, params);
        }
        else
        {
            try
            {
                fixture = new DefaultFixture(beanFactory.getBean(fixtureName));
            }
            catch (NoSuchBeanDefinitionException e)
            {
                fixture = new DefaultFixture(instantiateAsAutowiredBean(fixtureName));
            }
        }

        return fixture;
    }

    private Object instantiateAsAutowiredBean(String fixtureName) throws Exception
    {
        Class fixtureClass = loadType(fixtureName).getUnderlyingClass();

        BeanDefinition beanDef = new RootBeanDefinition(fixtureClass, RootBeanDefinition.AUTOWIRE_AUTODETECT);

        DefaultListableBeanFactory fallFactory = new DefaultListableBeanFactory(beanFactory);
        fallFactory.registerBeanDefinition(fixtureName, beanDef);

        return fallFactory.getBean(fixtureName);
    }
}

Hooking document execution

 public static class CustomSystemUnderDevelopment extends DefaultSystemUnderDevelopment
    {
        public CustomSystemUnderDevelopment( String... params )
        {
           
        }

       public void onStartDocument(Document document)
       {
          //this method is called before GreenPepper execute a document
       }

       public void onEndDocument(Document document)
       {
          //this method is called after GreenPepper has executed the document              
       }
    }