@Test
public void serviceReturnsEmptyFrequencyDataWhenSpecifiedFrequencyDataIsUnavailable() {

    Mockito.when(defaultFrequencyDao.getFrequencyData(variant)).thenReturn(FrequencyData.empty());
    FrequencyData result = instance.getVariantFrequencyData(variant, EnumSet.of(FrequencySource.LOCAL));
    assertThat(result, equalTo(FrequencyData.empty()));
}