@Test
public void equals() {

    VisualisationGraph graph1 = new VisualisationGraph();
    VisualisationGraph graph2 = new VisualisationGraph();
    assertTrue("2 fresh visualization (empty) graphs should be equal", graph1.equals(graph2));
    graph1.addNode("https://www.philippheinisch.de", "1.1.1.1");
    graph1.addEdge("https://www.philippheinisch.de", "https://www.bibleserver.com/");
    graph2.addEdge("https://www.philippheinisch.de", "https://www.bibleserver.com/");
    assertTrue("Adding a node pair (even over different circumstances should not de-equals the graphs!", graph1.equals(graph2));
    graph1.optimizeArrays();
    assertFalse("Nut optimazing the Arrays aof only one Graph should result in a nom equal result", graph1.equals(graph2));
    graph2.optimizeArrays();
    ;
    graph1.addNode("https://philippheinisch.de/aboutMe.html");
    graph2.addNode("https://philippheinisch.de/aboutMe.html");
    assertTrue("Final test with extend the arrays: new node", graph1.equals(graph2));
}