@Test
    public void twoEdgesCompareCorrectly() {
        Edge e = new Edge(null, null);
        Edge f = new Edge(null, null);
        Edge g = new Edge(null, null);
        e.setWeight(1);
        f.setWeight(1);
        g.setWeight(2);
        assertTrue(e.compareTo(g) < 0);
        assertTrue(g.compareTo(e) > 0);
        assertTrue(e.compareTo(f) == 0);
    }