### Question:
Pedigree { @JsonIgnore public int size() { return individuals.size(); } private  Pedigree(Collection<Individual> individuals); static Pedigree of(Collection<Individual> individuals); static Pedigree of(Individual... individuals); static Pedigree justProband(String id); static Pedigree empty(); @JsonIgnore boolean containsId(String id); @JsonIgnore Individual getIndividualById(String individualId); Set<Individual> getIndividuals(); @JsonIgnore Set<String> getIdentifiers(); @JsonIgnore int size(); @JsonIgnore boolean isEmpty(); @JsonIgnore int numFamilies(); @Override boolean equals(Object o); @Override int hashCode(); @Override String toString();  }### Answer:
@Test public void testSize() { assertThat(Pedigree.empty().size(), equalTo(0)); assertThat(Pedigree.justProband("Nemo").size(), equalTo(1)); assertThat(Pedigree.of(PROBAND, MOTHER, FATHER).size(), equalTo(3)); }