@Test
public void testGetSemanticProperties() {

	SingleInputSemanticProperties origProps = new SingleInputSemanticProperties();
	origProps.addForwardedField(0, 1);
	origProps.addForwardedField(2, 2);
	origProps.addForwardedField(3, 4);
	origProps.addForwardedField(6, 0);
	origProps.addReadFields(new FieldSet(0, 2, 4, 7));
	GroupCombineOperatorBase<?,?,?> op = mock(GroupCombineOperatorBase.class);
	when(op.getSemanticProperties()).thenReturn(origProps);
	when(op.getKeyColumns(0)).thenReturn(new int[]{3,2});
	when(op.getParameters()).thenReturn(new Configuration());
	GroupCombineNode node = new GroupCombineNode(op);
	SemanticProperties filteredProps = node.getSemanticPropertiesForLocalPropertyFiltering();
	assertTrue(filteredProps.getForwardingTargetFields(0, 0).size() == 0);
	assertTrue(filteredProps.getForwardingTargetFields(0, 2).size() == 1);
	assertTrue(filteredProps.getForwardingTargetFields(0, 2).contains(2));
	assertTrue(filteredProps.getForwardingTargetFields(0, 3).size() == 1);
	assertTrue(filteredProps.getForwardingTargetFields(0, 3).contains(4));
	assertTrue(filteredProps.getForwardingTargetFields(0, 6).size() == 0);
	assertTrue(filteredProps.getForwardingSourceField(0, 1) < 0);
	assertTrue(filteredProps.getForwardingSourceField(0, 2) == 2);
	assertTrue(filteredProps.getForwardingSourceField(0, 4) == 3);
	assertTrue(filteredProps.getForwardingSourceField(0, 0) < 0);
	assertTrue(filteredProps.getReadFields(0).size() == 4);
	assertTrue(filteredProps.getReadFields(0).contains(0));
	assertTrue(filteredProps.getReadFields(0).contains(2));
	assertTrue(filteredProps.getReadFields(0).contains(4));
	assertTrue(filteredProps.getReadFields(0).contains(7));
}