@Test
    public void testToConnectionMapCsvOnMoreConnectedMasses() {
        graph.addMasses(mass1, mass2, mass3, mass4);
        graph.addSpring(mass1, mass2);
        graph.addSpring(mass2, mass3);
        graph.addSpring(mass4, mass3); // mass4 -> mass3 | Important since this tests if
        graph.addSpring(mass4, mass2); // mass4 -> mass2 | the springs are sorted first!
        graph.getSprings().get(0).setConnectionType(FIXED_CONSTRAINT);

        result = GraphConverter.toConnectionMapCsv(graph);
        assertEquals(CONNECTION_MAP_PREAMBLE
                + "1,0," + FIXED_CONSTRAINT + "\n"
                + "2,1,1\n"
                + "3,1,1\n" // here, it has to be in acending order
                + "3,2,1\n",
                result);
    }