@Test
public void testInsertChild() {

	Instance instance_1 = new Instance( "inst 1" );
	Instance instance_1_1 = new Instance( "inst 11" );
	Assert.assertNull( instance_1.getParent());
	Assert.assertNull( instance_1_1.getParent());
	Assert.assertEquals( 0, instance_1.getChildren().size());
	InstanceHelpers.insertChild( instance_1, instance_1_1 );
	Assert.assertEquals( 1, instance_1.getChildren().size());
	Assert.assertEquals( instance_1_1, instance_1.getChildren().iterator().next());
	Assert.assertEquals( instance_1, instance_1_1.getParent());
	Assert.assertTrue( instance_1.getChildren().contains( instance_1_1 ));
	Assert.assertNull( instance_1.getParent());
	Assert.assertNotSame( instance_1, instance_1_1 );
}