Presented at the Ruby Drink-up of Sophia Antipolis on the 25th of January 2012 by Muriel Salvan (@MurielSalvan).

1. Piloting processes through standard I/O in Ruby Jan 25 th 2012 Muriel Salvan Open Source Lead developer and architect X-Aeon Solutions http://x-aeon.com

4. Kernel::open

5. systemu

6. PTY::spawn

7. ChildProcess

8. Open3::popen3

9. ProcessPilot

10. Aruba (used with Cucumber )

12. This is Line 2, after sleep 1

13. Enter string 1: My String 1

14. String 1 entered: My String 1

15. This is Line 1 on STDERR, before sleep 1

16. This is Line 2 on STDERR, after sleep 1

17. Enter string 2 from STDERR: My String 2

18. String 2 entered: My String 2

19. This is Line 3, before sleep 1

20. This is Line 4, after sleep 1 Output : Output on STDOUT only Output : Output on STDERR only Output : Output for interactive tests only Input : Input taken from STDIN sleep 1 sleep 1 sleep 1 Input from stdin Input from stdin

21. IO::popen IO . popen ( 'ruby test.rb' , 'r+' ) do | io | io . write ( "My String 1 My String 2 " ) io . close_write puts "stdout: #{io.read}” end

23. stderr support only for Ruby > 1.9

24. stderr support does not work on Windows

25. Does not work with Ruby programs that don't explicitly turn off stdout internal cache

26. Kernel::open Kernel :: open ( '|ruby test.rb', 'r+' ) do | io | puts io . gets # stdout Line 1 puts io . gets # stdout Line 2 puts io . read ( 31 ) # stdout Prompt sleep 1 io . write ( "My String 1 " ) puts io . gets # stdout String 1 sleep 1 io . write ( "My String 2 " ) puts io . gets # stdout Line 3 puts io . gets # stdout Line 4 end

28. Does not work with Ruby programs that don't explicitly turn off stdout internal cache

29. systemu require 'systemu' status, stdout, stderr = systemu ( 'ruby test.rb' , 0 => "My String 1 My String 2 " ) puts "stdout: #{stdout}" puts "stderr: #{stderr}"

31. stdin must be given to the process at startup time => No real time

32. stdout/err can only be accessed when process has exited => No real time

33. PTY::spawn require 'pty' PTY ::spawn ( 'ruby test.rb' ) do | stdout, stdin, pid | puts stdout. gets # stdout Line 1 puts stdout. gets # stdout Line 2 puts stdout. read ( 31 ) # stdout Prompt sleep 1 stdin. write ( "My String 1 " ) puts stdout. gets # Extra for input echoed puts stdout. gets # stdout String 1 puts stdout. gets # Should be on stderr puts stdout. gets # Should be on stderr puts stdout. read ( 43 ) # Should be on stderr sleep 1 stdin. write ( "My String 2 " ) puts stdout. gets # Extra for input echoed puts stdout. gets # Should be on stderr puts stdout. gets # stdout Line 3 puts stdout. gets # stdout Line 4 end

35. Mix stdout and stderr in the same IO => No stderr support

36. Echoes all input from stdin to stdout

37. ChildProcess require 'childprocess' require 'tempfile' lProcess = ChildProcess. build ( 'ruby' , 'test.rb' ) lProcess. duplex = true Tempfile . open ( 'stdout' ) do | oStdOUT | lProcess. io . stdout = oStdOUT Tempfile . open ( 'stderr' ) do | oStdERR | lProcess. io . stderr = oStdERR lProcess. start stdout = File . open ( oStdOUT. path , 'r' ) stderr = File . open ( oStdERR. path , 'r' ) stdin = lProcess. io . stdin waitfor ( stdout, 'This is Line 2' ) # Need active wait sleep 1 stdin. write ( "My String 1 " ) waitfor ( stderr, 'This is Line 2' ) # Need active wait sleep 1 stdin. write ( "My String 2 " ) waitfor ( stdout, 'This is Line 4' ) # Need active wait end end

39. Need active blocking read on stdout and stderr to wait for next line

40. Very unstable on native Windows

41. Does not work with Ruby programs that don't explicitly turn off stdout internal cache

42. Open3::popen3 require 'open3' Open3 ::popen3 ( 'ruby test.rb' ) do | stdin, stdout, stderr, wait_thr | puts stdout. gets # stdout Line 1 puts stdout. gets # stdout Line 2 puts stdout. read ( 31 ) # stdout Prompt sleep 1 stdin. write ( "My String 1 " ) puts stdout. gets # stdout String 1 puts stderr. gets # stderr Line 1 puts stderr. gets # stderr Line 2 puts stderr. read ( 43 ) # stderr Prompt sleep 1 stdin. write ( "My String 2 " ) puts stderr. gets # stderr String 2 puts stdout. gets # stdout Line 3 puts stdout. gets # stdout Line 4 end

44. Works on any OS

46. ProcessPilot require 'processpilot/processpilot' ProcessPilot ::pilot ( 'ruby' , 'test.rb' ) do | stdin, stdout, stderr, childproc | puts stdout. gets # stdout Line 1 puts stdout. gets # stdout Line 2 puts stdout. read ( 31 ) # stdout Prompt sleep 1 stdin. write ( "My String 1 " ) puts stdout. gets # stdout String 1 puts stderr. gets # stderr Line 1 puts stderr. gets # stderr Line 2 puts stderr. read ( 43 ) # stderr Prompt sleep 1 stdin. write ( "My String 2 " ) puts stderr. gets # stderr String 2 puts stdout. gets # stdout Line 3 puts stdout. gets # stdout Line 4 end

48. Works on any OS

49. Works with all Ruby programs , even if they don't explicitly turn off stdout internal cache

50. Provides time-out mechanisms in its API

52. Aruba When I run `ruby test.rb` interactively And I type "My String 1" And I type "My String 2" Then the stdout should contain : """ This is Line 1, before sleep 1 This is Line 2, after sleep 1 Enter string 1: String 1 entered: My String 1 This is Line 3, before sleep 1 This is Line 4, after sleep 1 """ And the stderr should contain : " "" This is Line 1 on STDERR, before sleep 1 This is Line 2 on STDERR, after sleep 1 Enter string 2 from STDERR: String 2 entered: My String 2 """

54. Works on any OS

56. No easy way to test for lines sequence between stdout and stderr flows

58. Kernel::open

59. systemu

60. PTY::spawn

61. ChildProcess

62. Open3::popen3

63. ProcessPilot

64. Aruba (used with Cucumber ) This presentation is available under CC-BY license by Muriel Salvan

65. Q/A