Fixes #742, #847, #807. This commit resolve ExcessivePublicCount, NullAssignment, DetachedTestCase and https://gitlab.univ-nantes.fr/naomod/mde/projet-2019/issues/742 and https://gitlab.univ-nantes.fr/naomod/mde/projet-2019/issues/847 and https://gitlab.univ-nantes.fr/naomod/mde/projet-2019/issues/807