validate_ruby!

# File lib/bundler/definition.rb, line 474
    def validate_ruby!
      return unless ruby_version

      if diff = ruby_version.diff(Bundler::RubyVersion.system)
        problem, expected, actual = diff

        msg = case problem
              when :engine
                "Your Ruby engine is #{actual}, but your Gemfile specified #{expected}"
              when :version
                "Your Ruby version is #{actual}, but your Gemfile specified #{expected}"
              when :engine_version
                "Your #{Bundler::RubyVersion.system.engine} version is #{actual}, but your Gemfile specified #{ruby_version.engine} #{expected}"
              when :patchlevel
                if !expected.is_a?(String)
                  "The Ruby patchlevel in your Gemfile must be a string"
                else
                  "Your Ruby patchlevel is #{actual}, but your Gemfile specified #{expected}"
                end
        end

        raise RubyVersionMismatch, msg
      end
    end