}

  @Test
  public void edges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.edges()).containsExactly(E11);
  }

  @Test
  public void incidentEdges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.incidentEdges(N1)).containsExactly(E11);

  }

  @Test
  public void edges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.edges()).containsExactly(E11);
  }

  @Test
  public void incidentEdges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.incidentEdges(N1)).containsExactly(E11);

  }

  @Test
  public void adjacentNodes_selfLoop() {
    assume().that(graph.allowsSelfLoops()).isTrue();

    putEdge(N1, N1);
    putEdge(N1, N2);
    assertThat(graph.adjacentNodes(N1)).containsExactly(N1, N2);
  }

  @Test
  public void predecessors_selfLoop() {
    assume().that(graph.allowsSelfLoops()).isTrue();

    putEdge(N1, N1);
    assertThat(graph.predecessors(N1)).containsExactly(N1);

  }

  @Test
  public void edges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.edges()).containsExactly(E11);
  }

  @Test
  public void incidentEdges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.incidentEdges(N1)).containsExactly(E11);

  }

  @Test
  public void adjacentNodes_selfLoop() {
    assume().that(graph.allowsSelfLoops()).isTrue();

    putEdge(N1, N1);
    putEdge(N1, N2);
    assertThat(graph.adjacentNodes(N1)).containsExactly(N1, N2);
  }

  @Test
  public void predecessors_selfLoop() {
    assume().that(graph.allowsSelfLoops()).isTrue();

    putEdge(N1, N1);
    assertThat(graph.predecessors(N1)).containsExactly(N1);

    MutableGraph<Integer> directedGraph = GraphBuilder.directed().allowsSelfLoops(false).build();
    directedGraph.putEdge(N1, N2);
    directedGraph.putEdge(N1, N3);
    directedGraph.putEdge(N2, N3);
    directedGraph.addNode(N4);

    MutableGraph<Integer> expectedClosure = GraphBuilder.directed().allowsSelfLoops(true).build();
    expectedClosure.putEdge(N1, N1);
    expectedClosure.putEdge(N1, N2);

    assertThat(networkString).contains("isDirected: " + network.isDirected());
    assertThat(networkString).contains("allowsParallelEdges: " + network.allowsParallelEdges());
    assertThat(networkString).contains("allowsSelfLoops: " + network.allowsSelfLoops());

    int nodeStart = networkString.indexOf("nodes:");
    int edgeStart = networkString.indexOf("edges:");
    String nodeString = networkString.substring(nodeStart, edgeStart);

  }

  @Test
  public void edges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.edges()).containsExactly(E11);
  }

  @Test
  public void incidentEdges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.incidentEdges(N1)).containsExactly(E11);

      }

      @Override
      public boolean isDirected() {
        return AbstractNetwork.this.isDirected();
      }

      @Override
      public boolean allowsSelfLoops() {
        return AbstractNetwork.this.allowsSelfLoops();
      }

      @Override
      public Set<N> adjacentNodes(N node) {
        return AbstractNetwork.this.adjacentNodes(node);
      }

      @Override

      }

      @Override
      public boolean isDirected() {
        return AbstractNetwork.this.isDirected();
      }

      @Override
      public boolean allowsSelfLoops() {
        return AbstractNetwork.this.allowsSelfLoops();
      }

      @Override
      public Set<N> adjacentNodes(N node) {
        return AbstractNetwork.this.adjacentNodes(node);
      }

      @Override