### Question:
AddFixedCurve implements Curve, ImmutableBean, Serializable { @Override public UnitParameterSensitivity yValueParameterSensitivity(double x) { return spreadCurve.yValueParameterSensitivity(x); } private  AddFixedCurve(
      Curve fixedCurve,
      Curve spreadCurve); static AddFixedCurve of(Curve fixedCurve, Curve spreadCurve); @Override CurveMetadata getMetadata(); @Override AddFixedCurve withMetadata(CurveMetadata metadata); @Override int getParameterCount(); @Override double getParameter(int parameterIndex); @Override ParameterMetadata getParameterMetadata(int parameterIndex); @Override AddFixedCurve withParameter(int parameterIndex, double newValue); @Override AddFixedCurve withPerturbation(ParameterPerturbation perturbation); @Override double yValue(double x); @Override UnitParameterSensitivity yValueParameterSensitivity(double x); @Override double firstDerivative(double x); @Override ImmutableList<Curve> split(); @Override AddFixedCurve withUnderlyingCurve(int curveIndex, Curve curve); static AddFixedCurve.Meta meta(); @Override AddFixedCurve.Meta metaBean(); Curve getFixedCurve(); Curve getSpreadCurve(); @Override boolean equals(Object obj); @Override int hashCode(); @Override String toString();  }### Answer:
@Test public void yParameterSensitivity() { for (int i = 0; i < X_SAMPLE.length; i++) { UnitParameterSensitivity dComputed = ADD_FIXED_CURVE.yValueParameterSensitivity(X_SAMPLE[i]); UnitParameterSensitivity dExpected = SPREAD_CURVE.yValueParameterSensitivity(X_SAMPLE[i]); assertThat(dComputed.compareKey(dExpected) == 0).isTrue(); assertThat(dComputed.getSensitivity().equalWithTolerance(dExpected.getSensitivity(), TOLERANCE_Y)).isTrue(); } }