assertThat(i.next()).isEqualTo(1);
    assertThat(i.hasNext()).isFalse();
  }

  public void testSingletonNullIteratorBasic() {
    Iterator<@Nullable Integer> i = singletonIterator(null);
    assertThat(i.hasNext()).isTrue();
    assertThat(i.next()).isEqualTo(null);
    assertThat(i.hasNext()).isFalse();
  }

  @GwtIncompatible // slow (~4s)