### Question:
ForwardIborRateComputationFn implements RateComputationFn<IborRateComputation> { @Override public PointSensitivityBuilder rateSensitivity( IborRateComputation computation, LocalDate startDate, LocalDate endDate, RatesProvider provider) { IborIndexRates rates = provider.iborIndexRates(computation.getIndex()); return rates.ratePointSensitivity(computation.getObservation()); } ForwardIborRateComputationFn(); @Override double rate(
      IborRateComputation computation,
      LocalDate startDate,
      LocalDate endDate,
      RatesProvider provider); @Override PointSensitivityBuilder rateSensitivity(
      IborRateComputation computation,
      LocalDate startDate,
      LocalDate endDate,
      RatesProvider provider); @Override double explainRate(
      IborRateComputation computation,
      LocalDate startDate,
      LocalDate endDate,
      RatesProvider provider,
      ExplainMapBuilder builder); static final ForwardIborRateComputationFn DEFAULT; }### Answer:
@Test public void test_rateSensitivity() { IborIndexRates mockIbor = mock(IborIndexRates.class); SimpleRatesProvider prov = new SimpleRatesProvider(); prov.setIborRates(mockIbor); when(mockIbor.ratePointSensitivity(GBP_LIBOR_3M_COMP.getObservation())).thenReturn(SENSITIVITY); ForwardIborRateComputationFn obsFn = ForwardIborRateComputationFn.DEFAULT; assertThat(obsFn.rateSensitivity(GBP_LIBOR_3M_COMP, ACCRUAL_START_DATE, ACCRUAL_END_DATE, prov)).isEqualTo(SENSITIVITY); }