assertThat(graph.nodes()).containsExactly("A");
    assertThat(graph.edges()).isEmpty();
  }

  @Test
  public void immutableValueGraphBuilder_putEdgeFromNodes() {
    ImmutableValueGraph<String, Integer> graph =
        ValueGraphBuilder.directed()
            .<String, Integer>immutable()
            .putEdgeValue("A", "B", 10)
            .build();