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
aggregates = columnHandle.getAggregateOnList( );
		assertEquals( 0, aggregates.size( ) );
		
		columnHandle.setAggregateOn( "agg 1" ); 
		columnHandle.addAggregateOn( "agg 2" ); 
		assertEquals( 2, columnHandle.getAggregateOnList( ).size( ) );
		columnHandle.clearAggregateOnList( );
		assertEquals( 0, columnHandle.getAggregateOnList( ).size( ) );
	}
	/**
	 * To test add arguments on the ComputedColumn structure.
	 * 
	 * @throws Exception
	 */
	public void testArguments( ) throws Exception
	{
		createDesign( );
		DataItemHandle data = designHandle.getElementFactory( ).newDataItem(
				"data1" ); 
		designHandle.getBody( ).add( data );
		ComputedColumn column = StructureFactory.createComputedColumn( );
		AggregationArgument argument = StructureFactory
				.createAggregationArgument( );
		argument.setName( "argu1" ); 
		argument.setValue( "value1" ); 
		column.addArgument( argument );
		argument = StructureFactory.createAggregationArgument( );
		argument.setName( "argu2" ); 
		argument.setValue( "value2" ); 
		column.addArgument( argument );