Better test for context-global-exception

[inkhey]

From:

        # FIXME - G.M - 17-05-2018 - Verify if:
        # - other view that work/raise an other exception do not go
        # into this code for handle this exceptions.
        # - response come clearly from there, not from web framework:
        #  Check not only http code, but also body.

Check those FIXME issue in test_context_exception_handling in order to have a better code for testing this feature.