assertThat(expected).hasMessageThat().contains("1, 2");
  }

  public void testOnlyElementMany() {
    IllegalArgumentException expected =
        assertThrows(
            IllegalArgumentException.class,
            () -> Stream.of(1, 2, 3, 4, 5, 6).collect(onlyElement()));
    assertThat(expected).hasMessageThat().contains("1, 2, 3, 4, 5, ...");
  }

        assertThrows(
            IllegalArgumentException.class, () -> networkAsMutableNetwork.addEdge(N4, N5, E12));
    assertThat(e).hasMessageThat().contains(ERROR_REUSE_EDGE);
    e = assertThrows(IllegalArgumentException.class, () -> addEdge(N2, N1, E12));
    assertThat(e).hasMessageThat().contains(ERROR_REUSE_EDGE);
  }

  @Test
  public void addEdge_parallelEdge_notAllowed() {
    assume().that(graphIsMutable()).isTrue();

        assertThrows(IllegalStateException.class, service::awaitRunning);
    assertThat(expected).hasCauseThat().hasMessageThat().isEqualTo("kaboom!");
    executionThread.join();

    assertTrue(service.startUpCalled);
    assertEquals(Service.State.FAILED, service.state());
    assertThat(service.failureCause()).hasMessageThat().isEqualTo("kaboom!");
  }

  private class ThrowOnStartUpService extends AbstractExecutionThreadService {

    assertThat(throwable).isInstanceOf(clazz);
    if (params.length == 1) {
      assertThat(throwable).hasMessageThat().isNull();
    } else if (params.length == 2) {
      assertThat(throwable).hasMessageThat().isEmpty();
    } else {
      assertThat(throwable)
          .hasMessageThat()
          .isEqualTo(Strings.lenientFormat("", Arrays.copyOfRange(params, 2, params.length)));
    }
  }

  /**

    assertThat(throwable).isInstanceOf(clazz);
    if (params.length == 1) {
      assertThat(throwable).hasMessageThat().isNull();
    } else if (params.length == 2) {
      assertThat(throwable).hasMessageThat().isEmpty();
    } else {
      assertThat(throwable)
          .hasMessageThat()
          .isEqualTo(Strings.lenientFormat("", Arrays.copyOfRange(params, 2, params.length)));
    }
  }

  /**

            () -> networkAsMutableNetwork.addEdge(N1, N2, EDGE_NOT_IN_GRAPH));
    assertThat(e).hasMessageThat().contains(ERROR_PARALLEL_EDGE);
    e =
        assertThrows(
            IllegalArgumentException.class,
            () -> networkAsMutableNetwork.addEdge(N2, N1, EDGE_NOT_IN_GRAPH));
    assertThat(e).hasMessageThat().contains(ERROR_PARALLEL_EDGE);
  }

  @Test

        assertThrows(IllegalArgumentException.class, () -> range.intersection(Range.open(3, 5)));
    assertThat(expected).hasMessageThat().contains("connected");
    expected =
        assertThrows(IllegalArgumentException.class, () -> range.intersection(Range.closed(0, 2)));
    assertThat(expected).hasMessageThat().contains("connected");
  }

  public void testIntersection_deFactoEmpty() {
    {

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

  @Test
  public void edgeValue_undirected_correct() {

      assertThat(e).hasMessageThat().isEqualTo("Cannot get() on a pending future.");
    }
  }

  static void verifyTimedGetOnPendingFuture(Future<?> future) {
    try {
      future.get(0, SECONDS);
      fail();
    } catch (Exception e) {
      assertThat(e).isInstanceOf(IllegalStateException.class);
      assertThat(e).hasMessageThat().isEqualTo("Cannot get() on a pending future.");
    }
  }

    equivalenceMock.replay();

    try {
      tester.addEquivalenceGroup(group1Item1, group1Item2).test();
    } catch (AssertionFailedError expected) {
      assertThat(expected)
          .hasMessageThat()
          .contains(
              "TestObject{group=1, item=2} [group 1, item 2] must be equivalent to "
                  + "TestObject{group=1, item=1} [group 1, item 1]");
      return;
    }
    fail();