@Test
public void testIsRoot() {

    assertTrue("expect isRoot " + container1, graph.isRoot(container1));
    assertFalse("expect not isRoot " + cont1sub1, graph.isRoot(cont1sub1));
    assertFalse("expect not isRoot " + cont1emb1, graph.isRoot(cont1emb1));
    assertTrue("expect isRoot " + container2, graph.isRoot(container2));
    assertFalse("expect not isRoot " + cont2sub1, graph.isRoot(cont2sub1));
    assertFalse("expect not isRoot " + cont2emb1, graph.isRoot(cont2emb1));
    graph.startedScan();
    assertTrue("expect isRoot " + container1, graph.isRoot(container1));
    assertTrue("expect isRoot " + cont1sub1, graph.isRoot(cont1sub1));
    assertTrue("expect isRoot " + cont1emb1, graph.isRoot(cont1emb1));
    assertTrue("expect isRoot " + container2, graph.isRoot(container2));
    assertTrue("expect isRoot " + cont2sub1, graph.isRoot(cont2sub1));
    assertTrue("expect isRoot " + cont2emb1, graph.isRoot(cont2emb1));
}