graph.putEdgeValue(1, 2, "A");
    assertThat(graph.edgeValue(EndpointPair.unordered(1, 2))).hasValue("A");
  }

  @Test
  public void edgeValue_undirected_backwards() {
    graph = ValueGraphBuilder.undirected().build();
    graph.putEdgeValue(1, 2, "A");
    assertThat(graph.edgeValue(EndpointPair.unordered(2, 1))).hasValue("A");
  }

  @Test
  public void edgeValue_undirected_mismatch() {

    assertThat(findLast(Stream.of())).isEmpty();
    assertThat(findLast(Stream.of("a", "b", "c", "d"))).hasValue("d");

    // test with a large, not-subsized Spliterator
    List<Integer> list =
        IntStream.rangeClosed(0, 10000).boxed().collect(Collectors.toCollection(LinkedList::new));
    assertThat(findLast(list.stream())).hasValue(10000);

    // no way to find out the stream is empty without walking its spliterator

    Iterable<String> list = newArrayList("cool", "pants");
    assertThat(Iterables.tryFind(list, Predicates.equalTo("cool"))).hasValue("cool");
    assertThat(Iterables.tryFind(list, Predicates.equalTo("pants"))).hasValue("pants");
    assertThat(Iterables.tryFind(list, Predicates.alwaysTrue())).hasValue("cool");
    assertThat(Iterables.tryFind(list, Predicates.alwaysFalse())).isAbsent();
    assertCanIterateAgain(list);
  }

    Iterable<String> list = newArrayList("cool", "pants");
    assertThat(Iterables.tryFind(list, Predicates.equalTo("cool"))).hasValue("cool");
    assertThat(Iterables.tryFind(list, Predicates.equalTo("pants"))).hasValue("pants");
    assertThat(Iterables.tryFind(list, Predicates.alwaysTrue())).hasValue("cool");
    assertThat(Iterables.tryFind(list, Predicates.alwaysFalse())).isAbsent();
    assertCanIterateAgain(list);
  }

    assertThat(Iterators.tryFind(iterator, Predicates.equalTo("cool"))).hasValue("cool");
  }

  public void testTryFind_lastElement() {
    Iterable<String> list = Lists.newArrayList("cool", "pants");
    Iterator<String> iterator = list.iterator();
    assertThat(Iterators.tryFind(iterator, Predicates.equalTo("pants"))).hasValue("pants");
  }

  public void testTryFind_alwaysTrue() {

      @SuppressWarnings("unchecked")
      K castKey = (K) key;
      @SuppressWarnings("unchecked") // similar to the above
      V castValue = (V) value;

      alertListenerIfPresent(castKey, castValue, RemovalCause.EXPLICIT);
      remove(key);
      return true;
    }
    return false;
  }

  @Override
  public boolean replace(K key, V oldValue, V newValue) {

    assertThat(Iterators.tryFind(iterator, Predicates.equalTo("cool"))).hasValue("cool");
  }

  public void testTryFind_lastElement() {
    Iterable<String> list = Lists.newArrayList("cool", "pants");
    Iterator<String> iterator = list.iterator();
    assertThat(Iterators.tryFind(iterator, Predicates.equalTo("pants"))).hasValue("pants");
  }

  public void testTryFind_alwaysTrue() {