add value checks in tests for svhn converters
add value checks in tests for svhn converters

glewis17/fuel,glewis17/fuel,mila-udem/fuel,hantek/fuel,janchorowski/fuel,capybaralet/fuel,hantek/fuel,dribnet/fuel,capybaralet/fuel,vdumoulin/fuel,chrishokamp/fuel,aalmah/fuel,harmdevries89/fuel,janchorowski/fuel,harmdevries89/fuel,udibr/fuel,markusnagel/fuel,chrishokamp/fuel,mila-udem/fuel,vdumoulin/fuel,dmitriy-serdyuk/fuel,dmitriy-serdyuk/fuel,aalmah/fuel,udibr/fuel,markusnagel/fuel,dribnet/fuel