@Test
	public void getVertexSetNeigourhoodTest2(){
		VertexSet s = new VertexSet();
		s.addVertex(city_graph.getCity(0));
		s.addVertex(city_graph.getCity(1));
		VertexSet v = city_graph.getVertexSetNeighbourhood(s);
		
		VertexSet expect = new VertexSet();
		expect.addVertex(city_graph.getCity(9));
		expect.addVertex(city_graph.getCity(3));
		expect.addVertex(city_graph.getCity(6));
		expect.addVertex(city_graph.getCity(2));
		
		assertTrue(v.equals(expect));
	}