expectedClosure.putEdge(N2, N2);
    expectedClosure.putEdge(N2, N3);
    expectedClosure.putEdge(N2, N4);
    expectedClosure.putEdge(N3, N1);
    expectedClosure.putEdge(N3, N2);
    expectedClosure.putEdge(N3, N3);
    expectedClosure.putEdge(N3, N4);
    expectedClosure.putEdge(N4, N1);
    expectedClosure.putEdge(N4, N2);
    expectedClosure.putEdge(N4, N3);
    expectedClosure.putEdge(N4, N4);

n2{margin-top:-.5rem!important}.mr-n2,.mx-n2{margin-right:-.5rem!important}.mb-n2,.my-n2{margin-bottom:-.5rem!important}.ml-n2,.mx-n2{margin-left:-.5rem!important}.m-n3{margin:-1rem!important}.mt-n3,.my-n3{margin-top:-1rem!important}.mr-n3,.mx-n3{margin-right:-1rem!important}.mb-n3,.my-n3{margin-bottom:-1rem!important}.ml-n3,.mx-n3{margin-left:-1rem!important}.m-n4{margin:-1.5rem!important}.mt-n4,.my-n4{margin-top:-1.5rem!important}.mr-n4,.mx-n4{margin-right:-1.5rem!important}.mb-n4,.my-n4{margi...

    MutableGraph<Integer> g1 = builder.build();
    MutableGraph<Integer> g2 = builder.build();

    // for g1, add 1->2 first, then 3->1
    g1.putEdge(N1, N2);
    g1.putEdge(N3, N1);

    // for g2, add 3->1 first, then 1->2
    g2.putEdge(N3, N1);
    g2.putEdge(N1, N2);

    assertThat(g1).isEqualTo(g2);
  }

  @Test
  public void equivalent_edgeDirectionsDiffer() {
    graph.putEdge(N1, N2);

  }

  @Test
  public void removeEdge_oneOfMany() {
    assume().that(graphIsMutable()).isTrue();

    putEdge(N1, N2);
    putEdge(N1, N3);
    putEdge(N1, N4);
    assertThat(graphAsMutableGraph.removeEdge(N1, N3)).isTrue();
    assertThat(graph.adjacentNodes(N1)).containsExactly(N2, N4);
  }

  @Test
  public void removeEdge_nodeNotPresent() {

  @Test
  public void equivalent_connectionsDiffer() {
    network.addEdge(N1, N2, E12);
    network.addEdge(N1, N3, E13);

    MutableNetwork<Integer, String> g2 = createNetwork(edgeType);
    // connect E13 to N1 and N2, and E12 to N1 and N3 => not equivalent
    g2.addEdge(N1, N2, E13);
    g2.addEdge(N1, N3, E12);

    assertThat(network).isNotEqualTo(g2);
  }

  @Test
  public void equivalent_connectionsDiffer() {
    network.addEdge(N1, N2, E12);
    network.addEdge(N1, N3, E13);

    MutableNetwork<Integer, String> g2 = createNetwork(edgeType);
    // connect E13 to N1 and N2, and E12 to N1 and N3 => not equivalent
    g2.addEdge(N1, N2, E13);
    g2.addEdge(N1, N3, E12);

    assertThat(network).isNotEqualTo(g2);
  }

  }

  @Test
  public void removeEdge_oneOfMany() {
    assume().that(graphIsMutable()).isTrue();

    putEdge(N1, N2);
    putEdge(N1, N3);
    putEdge(N1, N4);
    assertThat(graphAsMutableGraph.removeEdge(N1, N3)).isTrue();
    assertThat(graph.adjacentNodes(N1)).containsExactly(N2, N4);
  }

  @Test
  public void removeEdge_nodeNotPresent() {

    assertThat(networkAsMutableNetwork.addEdge(N2, N3, E23)).isTrue();
    assertThat(network.nodes()).containsExactly(N1, N5, N4, N2, N3);
    assertThat(network.edges()).containsExactly(E15, E41, E23);
    assertThat(network.edgesConnecting(N1, N5)).containsExactly(E15);
    assertThat(network.edgesConnecting(N4, N1)).containsExactly(E41);
    assertThat(network.edgesConnecting(N2, N3)).containsExactly(E23);

!important;\n}\n\n.mb-n2,\n.my-n2 {\n  margin-bottom: -0.5rem !important;\n}\n\n.ml-n2,\n.mx-n2 {\n  margin-left: -0.5rem !important;\n}\n\n.m-n3 {\n  margin: -1rem !important;\n}\n\n.mt-n3,\n.my-n3 {\n  margin-top: -1rem !important;\n}\n\n.mr-n3,\n.mx-n3 {\n  margin-right: -1rem !important;\n}\n\n.mb-n3,\n.my-n3 {\n  margin-bottom: -1rem !important;\n}\n\n.ml-n3,\n.mx-n3 {\n  margin-left: -1rem !important;\n}\n\n.m-n4 {\n  margin: -1.5rem !important;\n}\n\n.mt-n4,\n.my-n4 {\n  margin-top: -1.5rem !impor...

!important;\n}\n\n.mb-n2,\n.my-n2 {\n  margin-bottom: -0.5rem !important;\n}\n\n.ml-n2,\n.mx-n2 {\n  margin-left: -0.5rem !important;\n}\n\n.m-n3 {\n  margin: -1rem !important;\n}\n\n.mt-n3,\n.my-n3 {\n  margin-top: -1rem !important;\n}\n\n.mr-n3,\n.mx-n3 {\n  margin-right: -1rem !important;\n}\n\n.mb-n3,\n.my-n3 {\n  margin-bottom: -1rem !important;\n}\n\n.ml-n3,\n.mx-n3 {\n  margin-left: -1rem !important;\n}\n\n.m-n4 {\n  margin: -1.5rem !important;\n}\n\n.mt-n4,\n.my-n4 {\n  margin-top: -1.5rem !impor...