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
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2. Why Test?
   Ensure your code is correct
   Refactor with confidence
   Encourages lots of good practices
   Reference for how code works
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3. RUBY — TESTING
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4. THE EMILY WAY
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5. The Basics
   Write your test first
   Test behavior, not implementation
   “You ain’t gonna need it”
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6. Test First
   Test-Driven Development
   Figure out requirements before you
   start writing code
   Interface before implementation
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7. RED
   GREEN
   REFACTOR
   START
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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
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9. YAGNI
   Write only as much code
   as you need
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10. YAGNI
    Write only as much code
    as you need
    THIS IS SURPRISINGLY HARD
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11. RSPEC
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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
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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
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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
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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
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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)
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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_*
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18. Expect Matchers
    expect  {  ...  }.to  raise_error
    expect  {  ...  }.to  throw_symbol
    expect  {  ...  }.to  yield_control
    expect  {  ...  }.to  change{  it  }
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19. On Rails
    Different file layout than
    with Test::Unit
    Directories for model, controller,
    helper, and view specs
    Lots of Rails-specific matchers, etc.
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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
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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?
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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
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23. FACTORY GIRL
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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
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25. Syntax
    FactoryGirl.define  do
       factory  :user  do
           name  "John  Doe"
           factory  :admin  do
               admin  true
           end
       end
    end
    FactoryGirl.build(:user)
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26. AUTOTEST
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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
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28. AND FINALLY...
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29. DO
    Write your tests first
    Use contexts
    Use shared example groups
    Test your edge cases
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30. DON’T
    Test the framework
    Test the implementation
    Get too clever
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