Testing Ruby

A fairly high-level intro to testing Ruby using RSpec, Factory Girl, and Autotest.

Transcript

1. TESTING RUBY USING RSPEC WITH FACTORY GIRL AND AUTOTEST Thursday, July 5, 12
2. Why Test? Ensure your code is correct Refactor with confidence Encourages lots of good practices Reference for how code works Thursday, July 5, 12
3. RUBY — TESTING Thursday, July 5, 12
4. THE EMILY WAY Thursday, July 5, 12
5. The Basics Write your test first Test behavior, not implementation “You ain’t gonna need it” Thursday, July 5, 12
6. Test First Test-Driven Development Figure out requirements before you start writing code Interface before implementation Thursday, July 5, 12
7. RED GREEN REFACTOR START Thursday, July 5, 12
8. Test Behavior Behavior-Driven Development Unit tests are sentences starting with “it should” Use mocks for outside collaborators Changing the implementation shouldn’t break the test Thursday, July 5, 12
9. YAGNI Write only as much code as you need Thursday, July 5, 12
10. YAGNI Write only as much code as you need THIS IS SURPRISINGLY HARD Thursday, July 5, 12
11. RSPEC Thursday, July 5, 12
12. Why RSpec? Tests are very easy to read Syntax encourages good practices Specify behavior instead of verifying state Tests as documentation Tests are more expressive and more maintainable Thursday, July 5, 12
13. describe  Array  do    context  "when  empty"  do        subject  {  Array.new  }        it  {  should  be_empty  }        its(:first){  should  be_nil  }        its(:length){  should  ==  0  }    end end Basic Syntax Thursday, July 5, 12
14. More Syntax let(:user){  User.new  } before{  set_current_user(user)  } it  "should  be  reasonable"  do    "foo".should_not  eq("bar") end it  "should  be  magic"  do    pending  "invent  magic" end Thursday, July 5, 12
15. Shared Examples shared_examples  "collections"  do  | klass|    it  "is  empty  when  first  created"  do        klass.new.should  be_empty    end end describe  Array  do    include_examples  "collections",  Array end Thursday, July 5, 12
16. Matchers it.should  eq(expected) it.should  ==  expected it.should  be(expected) it.should  equal(expected) it.should  be  >  minimum it.should  be_within(x).of(y) Thursday, July 5, 12
17. Predicate Matchers it.should  be_a_kind_of(klass) it.should  be_true it.should  be_empty it.should  be_present it.should  be_* Thursday, July 5, 12
18. Expect Matchers expect  {  ...  }.to  raise_error expect  {  ...  }.to  throw_symbol expect  {  ...  }.to  yield_control expect  {  ...  }.to  change{  it  } Thursday, July 5, 12
19. On Rails Different file layout than with Test::Unit Directories for model, controller, helper, and view specs Lots of Rails-specific matchers, etc. Thursday, July 5, 12
20. Model Classic unit test Test each model individually Ideally, isolate from the database Check validations, but indirectly Add a context for each non-trivial method Thursday, July 5, 12
21. Controller Did you get the right response code? Did the expected redirect happen? Were the correct instance variables set? Were the right flash messages displayed? Thursday, July 5, 12
22. Legacy Write tests for what you have before you change it Write a failing test before you fix a bug Don’t try to do it all at once Thursday, July 5, 12
23. FACTORY GIRL Thursday, July 5, 12
24. Why Factories? Fixtures quickly get hard to maintain “What did I call the fixture for my admin user without an email?” Create the right object when you need it Use templates to keep it DRY Thursday, July 5, 12
25. Syntax FactoryGirl.define  do    factory  :user  do        name  "John  Doe"        factory  :admin  do            admin  true        end    end end FactoryGirl.build(:user) Thursday, July 5, 12
26. AUTOTEST Thursday, July 5, 12
27. Why Autotest? Never forget to run your tests again Get nearly instant notification when you break something Run the right tests at the right time Thursday, July 5, 12
28. AND FINALLY... Thursday, July 5, 12
29. DO Write your tests first Use contexts Use shared example groups Test your edge cases Thursday, July 5, 12
30. DON’T Test the framework Test the implementation Get too clever Thursday, July 5, 12