assertThat(graph.hasEdgeConnecting(endpoints.nodeU(), endpoints.nodeV())).isTrue();
        }
      }
    }

    sanityCheckSet(graph.edges());
    assertThat(graph.edges()).doesNotContain(EndpointPair.of(graph, new Object(), new Object()));
    assertThat(graph.edges()).isEqualTo(allEndpointPairs);
  }

  /**
   * Verifies that the {@code Set} returned by {@code nodes} has the expected mutability property

          assertThat(graph.hasEdgeConnecting(endpoints.nodeU(), endpoints.nodeV())).isTrue();
        }
      }
    }

    sanityCheckSet(graph.edges());
    assertThat(graph.edges()).doesNotContain(EndpointPair.of(graph, new Object(), new Object()));
    assertThat(graph.edges()).isEqualTo(allEndpointPairs);
  }

  /**
   * Verifies that the {@code Set} returned by {@code nodes} has the expected mutability property