@Test
public void shouldProduceAListOfGoldbachCompositions() throws Exception {

    List<SimpleEntry<Integer, List<Integer>>> compositions = P36.goldbach_list(IntStream.rangeClosed(9, 20));
    assertThat(compositions, hasSize(6));
    assertThat(compositions, hasItems(
            new SimpleEntry<>(10, Arrays.asList(3, 7)),
            new SimpleEntry<>(12, Arrays.asList(5, 7)),
            new SimpleEntry<>(14, Arrays.asList(3, 11)),
            new SimpleEntry<>(16, Arrays.asList(3, 13)),
            new SimpleEntry<>(18, Arrays.asList(5, 13)),
            new SimpleEntry<>(20, Arrays.asList(3, 17))
    ));
}