rails--rails/activesupport/lib/active_support/testing/isolation.rb

module ActiveSupport::Testing
  class ProxyTestResult
    def initialize
      @calls = []
    end

    def __replay__(result)
      @calls.each do |name, args|
        result.send(name, *args)
      end
    end

    def method_missing(name, *args)
      @calls << [name, args]
    end
  end

  module Isolation
    def self.forking_env?
      !ENV["NO_FORK"] && RUBY_PLATFORM !~ /mswin|mingw|java/
    end

    def run(result)
      unless defined?(@@ran_class_setup)
        self.class.setup
        @@ran_class_setup = true
      end

      yield(Test::Unit::TestCase::STARTED, name)

      @_result = result

      proxy = run_in_isolation do |proxy|
        super(proxy) { }
      end

      proxy.__replay__(@_result)

      yield(Test::Unit::TestCase::FINISHED, name)
    end

    module Forking
      def run_in_isolation(&blk)
        read, write = IO.pipe

        pid = fork do
          read.close
          proxy = ProxyTestResult.new
          yield proxy
          write.puts [Marshal.dump(proxy)].pack("m")
          exit!
        end

        write.close
        result = read.read
        Process.wait2(pid)
        Marshal.load(result.unpack("m")[0])
      end
    end

    module Subprocess
      # Crazy H4X to get this working in windows / jruby with
      # no forking.
      def run_in_isolation(&blk)
        require "tempfile"

        if ENV["ISOLATION_TEST"]
          proxy = ProxyTestResult.new
          yield proxy
          File.open(ENV["ISOLATION_OUTPUT"], "w") do |file|
            file.puts [Marshal.dump(proxy)].pack("m")
          end
          exit!
        else
          Tempfile.open("isolation") do |tmpfile|
            ENV["ISOLATION_TEST"]   = @method_name
            ENV["ISOLATION_OUTPUT"] = tmpfile.path

            load_paths = $-I.map {|p| "-I\"#{File.expand_path(p)}\"" }.join(" ")
            `#{Gem.ruby} #{load_paths} #{$0} #{ORIG_ARGV.join(" ")} -t\"#{self.class}\"`

            ENV.delete("ISOLATION_TEST")
            ENV.delete("ISOLATION_OUTPUT")

            return Marshal.load(tmpfile.read.unpack("m")[0])
          end
        end
      end
    end

    include forking_env? ? Forking : Subprocess
  end
end

# Only in subprocess for windows / jruby.
if ENV['ISOLATION_TEST']
  require "test/unit/collector/objectspace"
  class Test::Unit::Collector::ObjectSpace
    def include?(test)
      super && test.method_name == ENV['ISOLATION_TEST']
    end
  end
end