@Test
public void testAddDataSetElement()
{

    DataSet dsA = new DataSet( "DataSetA" );
    DataSet dsB = new DataSet( "DataSetB" );
    DataElement deA = new DataElement( "DataElementA" );
    DataElement deB = new DataElement( "DataElementB" );
    dsA.addDataSetElement( deA );
    dsA.addDataSetElement( deB );
    dsB.addDataSetElement( deA );
    assertEquals( 2, dsA.getDataSetElements().size() );
    assertEquals( 1, dsB.getDataSetElements().size() );
    assertEquals( 2, deA.getDataSetElements().size() );
    assertEquals( 1, deB.getDataSetElements().size() );
}