@Test
public void getKnownGeneIdentifiers() throws Exception {

    Set<GeneIdentifier> geneIdentifiers = ImmutableSet.copyOf(TestGeneFactory.buildGeneIdentifiers());
    Mockito.when(geneFactory.getGeneIdentifiers()).thenReturn(geneIdentifiers);
    assertThat(instance.getKnownGeneIdentifiers(), equalTo(geneIdentifiers));
}