Bug 200645 Can't save custom aggregate function's information into model in computed column page
model/org.eclipse.birt.report.model.tests/test/org/eclipse/birt/report/model/api/ComputedColumnHandleTest.java
public void testSimpleListProperties( ) throws Exception
	{
		createDesign( );
		DataItemHandle data = designHandle.getElementFactory( ).newDataItem(
				"data1" ); 
		designHandle.getBody( ).add( data );
		ComputedColumn column = StructureFactory.createComputedColumn( );
		column.setName( "column 1" ); 
		column.setExpression( "expression 1" ); 
		
		column.setAggregateOn( "agg 1" ); 
		column.addAggregateOn( "agg 2" ); 
		assertEquals( 2, column.getAggregateOnList( ).size( ) );
		column.clearAggregateOnList( );
		assertEquals( 0, column.getAggregateOnList( ).size( ) );
		ComputedColumnHandle columnHandle = data.addColumnBinding( column,
				false );
		AggregationArgument argument = new AggregationArgument( );
		argument.setName( "arg_1" ); 
		argument.setValue( "argument 1" ); 
		columnHandle.addArgument( argument );
		Iterator iter = columnHandle.argumentsIterator( );
		assertTrue( iter.hasNext( ) );
		columnHandle.removeArgument( argument );
		iter = columnHandle.argumentsIterator( );
		assertFalse( iter.hasNext( ) );
		columnHandle.addAggregateOn( "group 1" ); 
		List aggregates = columnHandle.getAggregateOnList( );
		assertEquals( 1, aggregates.size( ) );
		columnHandle.removeAggregateOn( "group 1" );