assertThat(transpose.edgeConnectingOrNull(N1, N2)).isEqualTo(E21);
    AbstractNetworkTest.validateNetwork(transpose);
  }

  @Test
  public void inducedSubgraph_graph() {
    Set<Integer> nodeSubset = ImmutableSet.of(N1, N2, N4);

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