### Question:
CompoundNetworkHandler implements INetworkHandler { @Override public void fillGradientsResponse(Gradients gradients) { for(INetworkHandler handler : networkHandlers) { handler.fillGradientsResponse(gradients); } } CompoundNetworkHandler(INetworkHandler... networkHandlers); @Override void notifyGradientCalculation(); @Override void notifyIterationDone(); @Override void performFit(FeaturesLabels featuresLabels); @Override void performGradientsComputation(FeaturesLabels featuresLabels); @Override void fillGradientsResponse(Gradients gradients); @Override void applyGradient(Gradients gradients, long batchSize); @Override INDArray[] recurrentStepOutput(Observation observation); @Override INDArray[] batchOutput(INDArray batch); @Override void resetState(); @Override INetworkHandler clone(); @Override void copyFrom(INetworkHandler from);  }### Answer:
@Test public void when_callingFillGradientsResponse_expect_fillGradientsResponseIsCalledOnHandlers() { setup(false); Gradients gradientsMock = mock(Gradients.class); sut.fillGradientsResponse(gradientsMock); verify(handler1, times(1)).fillGradientsResponse(gradientsMock); verify(handler2, times(1)).fillGradientsResponse(gradientsMock); }