Test coverage of Raman simulation

[jktjkt]

Hi @aleFerrari , the Raman simulation is currently not covered by automated tests (this is visible in the coverage report saying "codecov/project 65.59% (-13.82%) compared to 71d6a11*).

It would be nice if there is a simple test checking that the simulation engine works well. I think that the scenario should be kept reasonably simple, with just a few signals being checked and with a simplified topology (just one link). I'll be happy to help.

[aleFerrari]

Ok, I will do it. If it is ok will fork from the develop branch.

[cgkelly]

I have tried the Raman simulation by defining a RamanFiber span, and defining the Raman pump powers and frequencies.
I get the expected Raman gain, but I do not see any gain ripple due to the spacing of the Raman pumps. (I'm not seeing any gain ripple in general, but this is a broader topic even for EDFA only spans that I'm looking into).

[jktjkt]

I have tried the Raman simulation by defining a RamanFiber span, and defining the Raman pump powers and frequencies.
I get the expected Raman gain, but I do not see any gain ripple due to the spacing of the Raman pumps. (I'm not seeing any gain ripple in general, but this is a broader topic even for EDFA only spans that I'm looking into).

@cgkelly , I've created a bugreport for this at #398 .