You have to test multiple versions of your gem's dependencies. You used Appraisal. It's super affective!

So, it seems like you've finished writing your awesome gem. However, are you sure that your gem is working perfectly against multiple versions of its dependency? Are you sure that you didn't break any backward compatibility? In this talk, I'm going to show you the approach we have been taken to test our gems against multiple versions of dependencies, such as testing against Rails 3.2 and Rails 3.1. I'm also going to introduce you to our gem called "Appraisal" which helps you generating Gemfiles to be used with Bundler, and also guide it to running your test suite against those multiple Gemfiles. Lastly, I'm going to show you how you can config Travis CI to test your gem against those multiple versions of dependencies.

Presented at RubyKaigi 2013 on May 30, 2013.

Video is available at http://vimeo.com/69748748

Transcript

1. You have to test multiple versions of your gem’s dependencies. You used Appraisal. It’s super effective!
2. ϖϨϜɹγνϟψΪτ Prem Sichanugrist Developer at thoughtbot @sikachu /sikachu
4. Published your gem?
5. Fully tested?
6. Works with older version of dependencies?
7. Works with older version of dependencies?
8. Why testing with multiple versions?
9. People doesn’t update their project’s dependencies
10. People install your gem
11. Your gem is only tested against newer version of its dependency
12. “This gem doesn’t work”
14. Works with latest version != Works with old versions
15. ~>
16. SemVer Semantic Versioning
17. ~> 3.2
18. ~> 3.2
19. ~> 3.2
20. People don’t follow SemVer
21. People don’t follow SemVer
23. Supported Rails Versions • 3.1.x • 3.2.x
24. Supported Rails Versions • 3.1.x • 3.2.x • 4.0.0
25. Supported Rails Versions • 3.0.x • 3.1.x • 3.2.x • 4.0.0
26. Supported Rails Versions • 2.3.x • 3.0.x • 3.1.x • 3.2.x • 4.0.0
27. How?
28. Before Bundler
29. Uninstall and reinstall
30. $ gem uninstall activesupport $ gem install activesupport -v 3.1.12 $ rake $ gem install activesupport $ rake
31. ·͍ͣ (Bad)
32. Why was this so bad? • Time consuming • Can’t test against multiple versions at once • Doesn’t handle dependency of dependency • Dependency hell • $ rm -Rf $GEM_HOME
33. Test in isolation
34. Gemset
35. rbenv (with rbenv-gemset)
36. $ rvm gemset create rails-3-2 $ rvm gemset use rails-3-2 $ gem install rails -v 3.2.13 $ rake $ rvm gemset create rails-3-1 $ rvm gemset use rails-3-1 $ gem install rails -v 3.1.12 $ rake # ...
37. $ rvm @rails-3-1,@rails-3-2 do rake
39. This is good, but ... • Waste of space; gems are not shared • Contributors need to use Ruby manager that supports Gemset • May need to have bootstrap script to setup gemsets
41. Multiple Gemfiles
42. !"" Gemfile !"" rails-3-1.gemfile !"" rails-3-2.gemfile ...
43. rails-3-1.gemfile: source "http://rubygems.org" gem "rails", "~> 3.1.12" gem "rspec"
44. rails-3-2.gemfile: source "http://rubygems.org" gem "rails", "~> 3.2.13" gem "rspec"
45. $ bundle install --gemfile=rails-3-2.gemfile $ export BUNDLE_GEMFILE=rails-3-2.gemfile $ bundle exec rake $ bundle install --gemfile=rails-3-1.gemfile $ export BUNDLE_GEMFILE=rails-3-1.gemfile $ bundle exec rake
48. Still hard to maintain
49. Still have to edit Gemfiles by hand
50. Have to specify dependencies over and over
51. Adding new dependency
52. Adding new dependency ... edit multiple files!
53. No easy way to test all the versions at once
55. “There should be a better way to do this”
56. Appraisal
57. Set multiple versions of dependencies in one place
58. Merge dependencies and generate Gemfiles
59. Setup environment for Bundler
61. Demo
62. Gemfile: source "http://rubygems.org" gem "rails" gem "rspec" gem "appraisal"
63. Gemfile: source "http://rubygems.org" gemspec
64. Appraisals: appraise "rails-3-1" do gem "rails", "~> 3.1.12" end appraise "rails-3-2" do gem "rails", "~> 3.2.13" end
65. Rakefile: require "bundler/setup" require "appraisal" task "test" do # ... end
66. Rakefile: require "bundler/setup" require "appraisal" task "test" do # ... end
67. # Generate Gemfiles $ rake appraisal:gemfiles # Install dependencies $ rake appraisal:install
68. # Run "test" task against all versions $ rake appraisal test # Run "test" task against a single version $ rake appraisal:rails-3-1 test
69. Appraisal • Allow you to set dependencies in a single place • Generate sub-Gemfiles for you • Install multiple versions of dependencies • Setup Bundler to use the correct version of dependency
71. Show that your gem is working with multiple versions of dependency
72. .travis.yml: gemfile: - gemfiles/rails_3_1.gemfile - gemfiles/rails_3_2.gemfile
76. Remember
78. Test it against multiple versions of its dependencies
79. Test it against multiple versions of its dependencies by using Appraisal x
82. RUBYKAIGI Promo code: $20 off first month of Prime http://learn.thoughtbot.com ͋Γ͕ͱ͏͍͟͝·͢ʂ