class Gem::Resolver::InstallerSet

def ensure_required_ruby_version_met(spec) # :nodoc:
  if rrv = spec.required_ruby_version
    ruby_version = Gem.ruby_version
    unless rrv.satisfied_by? ruby_version
      raise Gem::RuntimeRequirementNotMetError,
        "#{spec.full_name} requires Ruby version #{rrv}. The current ruby version is #{ruby_version}."
    end
  end
end