Refactor AssignArgument spec
Refactor AssignArgument spec

rmosolgo/graphql-ruby,xuorig/graphql-ruby,nevesenin/graphql-ruby,rmosolgo/graphql-ruby,nevesenin/graphql-ruby,rmosolgo/graphql-ruby,nevesenin/graphql-ruby,nevesenin/graphql-ruby,xuorig/graphql-ruby,rmosolgo/graphql-ruby,xuorig/graphql-ruby