@Test
public void isConnectedTest() {

    IAtomContainer singleBond = builder.newInstance(IAtomContainer.class);
    singleBond.addAtom(builder.newInstance(IAtom.class, "C"));
    singleBond.addAtom(builder.newInstance(IAtom.class, "C"));
    singleBond.addBond(0, 1, IBond.Order.SINGLE);
    SignatureQuotientGraph quotientGraph = new SignatureQuotientGraph(singleBond);
    Assert.assertTrue(quotientGraph.isConnected(0, 1));
}