assertThat(graph.hasEdgeConnecting(EndpointPair.ordered(1, 2))).isFalse();
    assertThat(graph.hasEdgeConnecting(EndpointPair.ordered(2, 1))).isFalse();
  }

  @Test
  public void edgeValueOrDefault_directed_correct() {
    graph = ValueGraphBuilder.directed().build();
    graph.putEdgeValue(1, 2, "A");
    assertThat(graph.edgeValueOrDefault(EndpointPair.ordered(1, 2), "default")).isEqualTo("A");
  }

  @Test

            IllegalArgumentException.class, () -> graph.edgeValue(EndpointPair.ordered(2, 1)));
    assertThat(e).hasMessageThat().contains(ENDPOINTS_MISMATCH);
  }

  @Test
  public void edgeValueOrDefault_directed_correct() {
    graph = ValueGraphBuilder.directed().build();
    graph.putEdgeValue(1, 2, "A");
    assertThat(graph.edgeValueOrDefault(EndpointPair.ordered(1, 2), "default")).isEqualTo("A");
  }

  @Test