Provide tests for scenarios identifying fibers

The simulator requires unit and integration tests in general. A specific set of scenarios provided by naoyuki.tamura in an email to H Siddiqui on 2018-08-13 and copied helps to focus such tests.

Unit and integration tests should be created for these scenarios.

[...] can you now tell which fiber spectrum on a simulated 2D image is from which fiber at which position on the telescope focal plane, with what input from the sky on it (e.g. sky only or object and sky), and can the pipeline correctly handle that set of information? Is the simulator ready to be given data of fiber-to-target allocation so that you can simulate spectra of astronomical objects from individual fibers?