Testing Legacy Rails Apps
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Presentation at Rails Conf 2007 about adding tests to legacy ruby on rails applications.
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Testing Legacy Rails Apps
- 1. Testing Legacy Rails Applications Evan ‘rabble’ Henshaw-Plath Yahoo! Brickhouse anarchogeek.com - testingrails.com presentation slides - slideshare.net/rabble
- 2. Do We Have Legacy Already? Yes, thousands of rails apps have been built and deployed over the last three years. Many of us included few or no tests. The test-less apps still need debugging, which should be done with tests.
- 3. Testing == Health Food? “We started the tests, but haven’t been updating them” “Who has time for tests?” “Testing means writing twice as much code.”
- 5. no, really, it is
- 6. Starting
- 8. Get Rake Working brickhouse:~/code/legacy_testing rabble$ rake (in /Users/rabble/code/legacy_testing) /opt/local/bin/ruby -Ilib:test quot;/opt/local/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake/rake_test_loader.rbquot; /opt/local/bin/ruby -Ilib:test quot;/opt/local/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake/rake_test_loader.rbquot; #42000Unknown database 'legacy_testing_development' /opt/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/vendor/mysql.rb:523:in `read' /opt/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/vendor/mysql.rb:153:in `real_connect' /opt/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/connection_adapters/ mysql_adapter.rb:389:in `connect' /opt/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/connection_adapters/ mysql_adapter.rb:152:in `initialize'
- 9. Create your test db mysqladmin -uroot create railsapp_test
- 10. Use Migrations brickhouse:~/code/legacy_testing rabble$ rake db:migrate (in /Users/rabble/code/legacy_testing) == CreateArticles: migrating ==================== -- create_table(:articles) -> 0.2749s == CreateArticles: migrated (0.2764s) =============
- 11. Try Rake Again brickhouse:~/code/legacy_testing rabble$ rake (in /Users/rabble/code/legacy_testing) /opt/local/bin/ruby -Ilib:test quot;/opt/local/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake/rake_test_loader.rbquot; quot;test/unit/ article_test.rbquot; Loaded suite /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake/rake_test_loader Started . Finished in 0.316844 seconds. 1 tests, 1 assertions, 0 failures, 0 errors /opt/local/bin/ruby -Ilib:test quot;/opt/local/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake/rake_test_loader.rbquot; quot;test/ functional/blog_controller_test.rbquot; Loaded suite /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake/rake_test_loader Started . Finished in 0.243161 seconds. 1 tests, 1 assertions, 0 failures, 0 errors /opt/local/bin/ruby -Ilib:test quot;/opt/local/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake/rake_test_loader.rbquot;
- 13. Ok now we’re ready to get started
- 14. One Step At A Time
- 15. find a bug - write a test
- 16. refractor a method write a test
- 17. Treat Each Method As Box
- 18. Test One Thing At A Time
- 19. What Goes In? What Comes Out?
- 20. Running Tests rake & directly
- 21. Running Tests with rake rake test # Test all units and functionals rake test:functionals # Run the functional tests in test/functional rake test:integration # Run the integration tests in test/integration rake test:plugins # Run the plugin tests in vendor/plugins/**/test rake test:recent # Test recent changes rake test:uncommitted # Test changes since last checkin (svn only) rake test:units # Run the unit tests in test/unit
- 22. running tests directly Test::Unit automatic runner. Usage: blog_controller_test.rb [options] [-- untouched arguments] run them all ruby article_controller_test.rb give it a test name ruby article_controller_test.rb -n test_show try regular expressions ruby article_controller_test.rb -n /show/ get help: ruby --help
- 23. An Example def User.find_popular(n=20) sql = quot;select u.*, count(j.user_id) as popularity from users u, talks_users j where u.id = j.user_id group by j.user_id order by popularity desc limit #{n}quot; return User.find_by_sql(sql) end
- 24. An Example def User.find_popular(n=20) sql = quot;select u.*, count(j.user_id) as popularity from users u, talks_users j where u.id = j.user_id group by j.user_id order by popularity desc limit #{n}quot; return User.find_by_sql(sql) end def test_popular assert_nothing_raised { users = User.find_popular(2) } assert_equal 2, users.size, quot;find_popular should return two usersquot; assert users.first.popularity > users.last.popularity, quot;should sort popular usersquot; end $ ruby ./test/unit/user_test -n test_popular brickhouse:~/code/icalico/trunk/test/unit rabble$ ruby user_test.rb -n /popular/ Loaded suite user_test Started . Finished in 0.290563 seconds.
- 25. Refactor def self.find_popular(n=20) return conference.attendees.find(:all, :select => quot;users.*, count(talks_users.user_id) as popularityquot;, :joins => quot;LEFT JOIN talks_users on users.id = talks_users.user_idquot;, :group => quot;talks_users.user_idquot;, :order => 'popularity', :limit => n ) end $ ruby ./test/unit/user_test -n test_popular brickhouse:~/code/icalico/trunk/test/unit rabble$ ruby user_test.rb -n /popular/ Loaded suite user_test Started F Finished in 0.290563 seconds. 1) Failure: test_popular(UserTest) [user_test.rb:10]: Exception raised: Class: <NoMethodError> Message: <quot;You have a nil object when you didn't expect it!nThe error occured while evaluating nil.attendeesquot;> ---Backtrace--- /Users/rabble/code/icalico/trunk/config/../app/models/user.rb:35:in `find_popular' user_test.rb:10:in `test_popular' user_test.rb:10:in `test_popular' ---------------
- 26. Refactor def self.find_popular(n=20) return self.find(:all, :select => quot;users.*, count(talks_users.user_id) as popularityquot;, :conditions => [quot;users.conference_id = ? quot;, conference.id], :joins => quot;LEFT JOIN talks_users on users.id = talks_users.user_idquot;, :group => quot;talks_users.user_idquot;, :order => 'popularity', :limit => n ) end $ ruby ./test/unit/user_test -n test_popular brickhouse:~/code/icalico/trunk/test/unit rabble$ ruby user_test.rb -n /popular/ Loaded suite user_test Started . Finished in 0.290563 seconds.
- 27. build test from logs ./log/development.log Processing ArticlesController#show (for 0.0.0.0 at 2006-07-20 11:28:23) [GET] Session ID: Parameters: {quot;actionquot;=>quot;showquot;, quot;idquot;=>quot;2quot;, quot;controllerquot;=>quot;articlesquot;} Article Load (0.002371) SELECT * FROM articles LIMIT 1 Rendering within layouts/articles Rendering articles/show Article Columns (0.007194) SHOW FIELDS FROM articles Completed in 0.10423 (9 reqs/sec) | Rendering: 0.08501 (81%) | DB: 0.01022 (9%) | 200 OK [http://test.host/articles/show/1]
- 28. the functional test ./test/functional/article_controller_test.rb require File.dirname(__FILE__) + '/../test_helper' require 'articles_controller' # Re-raise errors caught by the controller. class ArticlesController def rescue_action(e) raise e end end class ArticlesControllerTest < Test::Unit::TestCase def setup @controller = ArticlesController.new @request = ActionController::TestRequest.new @response = ActionController::TestResponse.new end # Replace this with your real tests. def test_truth assert true end end
- 29. get the params ./log/development.log Processing ArticlesController#show (for 0.0.0.0 at 2006-07-20 11:28:23) [GET] Session ID: Parameters: {quot;actionquot;=>quot;showquot;, quot;idquot;=>quot;2quot;, quot;controllerquot;=>quot;articlesquot;} Article Load (0.002371) SELECT * FROM articles LIMIT 1 Rendering within layouts/articles Rendering articles/show Article Columns (0.007194) SHOW FIELDS FROM articles Completed in 0.10423 (9 reqs/sec) | Rendering: 0.08501 (81%) | DB: 0.01022 (9%) | 200 OK [http://test.host/articles/show/1]
- 30. what to test? 1. Assert that the page action rendered and returned successful HTTP response code, i.e. 200. 2. Assert that the correct template was rendered. 3. Assert that action assigns a value to the @article variable. 4. Assert that the right @article object was loaded.
- 31. writing the test ./test/functional/article_controller_test.rb def test_show get :show, {quot;actionquot;=>quot;showquot;, quot;idquot;=>quot;2quot;, quot;controllerquot;=>quot;articlesquot;} #confirm that the http response was a 200 (i.e. success) assert_response :success #confirm that the correct template was used for this action assert_template 'articles/show' #confirm that the variable @article was assigned a value assert assigns( :article ) #confirm that the @article object loaded has the id we want assert_equal 2, assigns( :article ).id end
- 32. running the test rabble:~/code/tblog/test/functional evan$ ruby articles_controller_test.rb -n test_show Loaded suite articles_controller_test Started F Finished in 0.625045 seconds. 1) Failure: test_show(ArticlesControllerTest) [articles_controller_test.rb:27]: <2> expected but was <1>. 1 tests, 4 assertions, 1 failures, 0 errors
- 33. fix the bug The old code app/controller/articles_controller.rb: def show @article = Article.find(:first) end The fix is easy, we update it so the Article.find method app/controller/articles_controller.rb: def show @article = Article.find(params[:id]) end
- 34. running the test rabble:~/code/tblog/test/functional evan$ ruby articles_controller_test.rb -n test_show Loaded suite articles_controller_test Started . Finished in 0.426828 seconds. 1 tests, 3 assertions, 0 failures, 0 errors
- 35. test coverage
- 36. rake stats brickhouse:~/code/icalico/trunk rabble$ rake stats (in /Users/rabble/code/icalico/trunk) +----------------------+-------+-------+---------+---------+-----+-------+ | Name | Lines | LOC | Classes | Methods | M/C | LOC/M | +----------------------+-------+-------+---------+---------+-----+-------+ | Helpers | 107 | 81 | 0| 9| 0| 7| | Controllers | 517 | 390 | 10 | 52 | 5| 5| | Components | 0| 0| 0| 0| 0| 0| | Functional tests | 416 | 299 | 18 | 58 | 3| 3| | Models | 344 | 250 | 8| 37 | 4| 4| | Unit tests | 217 | 159 | 9| 25 | 2| 4| | Libraries | 257 | 162 | 4| 32 | 8| 3| | Integration tests | 0| 0| 0| 0| 0| 0| +----------------------+-------+-------+---------+---------+-----+-------+ | Total | 1858 | 1341 | 49 | 213 | 4| 4| +----------------------+-------+-------+---------+---------+-----+-------+ Code LOC: 883 Test LOC: 458 Code to Test Ratio: 1:0.5
- 38. rcov test coverage what needs to be tested?
- 39. rcov test coverage what gets executed when you run tests
- 41. rcov test coverage per file reports
- 43. autotest because sometimes our tests can run themselves
- 44. autotest
- 46. You can go deeper
- 48. zentest
- 49. focus on the bugs
- 51. Get Your Feet Wet Next: Evan ‘rabble’ Henshaw-Plath Yahoo! Brickhouse anarchogeek.com Heckle testingrails.com slides: slideshare.net/rabble