:new: Add some tests for message-registry
:new: Add some tests for message-registry

AtomLinter/Linter,levity/linter,DanPurdy/linter,steelbrain/linter,shawninder/linter,blakeembrey/linter,JohnMurga/linter,e-jigsaw/Linter,atom-community/linter,AsaAyers/linter,Arcanemagus/linter