01_slide.md

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BDD (or TDD, or software development, or whatever)

• with Ragel

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Externalize Evidence of Operation

• Make assertions on the collected evidence

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• 1st passing test example (spec side-by-side w/ ragel)

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• changes (spec side-by-side w/ ragel)

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• coupla refactorings as we learned more

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• shared examples

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• pretty_formatter.feature

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What the Tests Told Us

.notes Event based design of Gherkin came about out of need to easily test lexer .notes Remember regex == state machine, so inherently event driven .notes Acceptance: when Ragel finishes its work and the current state is not less than the final lexer state

• Parameterize the Lexer's ctor with a listener
• (Dependency Injection)
• Compose listeners for flexibility and additional layers of responsibility
• Test using a Test Spy listener: SexpRecorder

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@@@ Ruby
class Lexer
  %%{
    machine lexer;
    action do_action {
      # Send the appropriate messages to the listener
    }
    main := 'foo' $do_action;
  }%%

  def initialize(listener)
    @listener = listener
    %% write data;
  end

  def scan(text)
    data = text.unpack("c*")

    %% write init;
    %% write exec;
  end
end

!SLIDE .notes We know not really sexps but annoying pedants is more fun than being correct

@@@ Ruby
class SexpRecorder
  def initialize
    @sexps = []
  end

  def method_missing(event, *args)
    @sexps << [event] + args
  end

  def to_sexp
    @sexps
  end
end

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Feature: Autocuke

  Scenario: Motivation
    Given plain text is boring
    Then a GUI must be the answer

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@@@ Ruby
recorder = SexpRecorder.new
Lexer.new(recorder).scan(feature)

recorder.to_sexp.should == [
  [:feature,  "Feature",  "Autocuke",                 1],
  [:scenario, "Scenario", "Motivation",               2],
  [:step,     "Given",    "plain text is boring",     3],
  [:step,     "Then",     "a GUI must be the answer", 4]
]

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A Real Test

@@@ Ruby
it "should parse steps with inline py_string" do
  scan("Given I have a string\n\"\"\"\nhello\nworld\n\"\"\"")
  @listener.to_sexp.should == [
    [:step, "Given ", "I have a string", 1],
    [:py_string, "hello\nworld", 2],
    [:eof]
  ]
end

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Cucumber

@@@ Cucumber
Given a Gherkin parser
When the following text is parsed:
  """
  Feature: Advanced Lulzfinding Mechanism
    Scenario: Monty Python
      Given the following excerpt:
        \"\"\"
        WOMAN:  Who are the Britons?
        ARTHUR:  Well, we all are. we're all Britons and I am your king.
        WOMAN:  I didn't know we had a king.  I thought we were an autonomous
            collective.
        DENNIS:  You're fooling yourself.  We're living in a dictatorship.
            A self-perpetuating autocracy in which the working classes--
        WOMAN:  Oh there you go, bringing class into it again.
        DENNIS:  That's what it's all about if only people would--
        ARTHUR:  Please, please good people.  I am in haste.  Who lives
            in that castle?  
        \"\"\"
      When I read it
      Then I should be amused
  """
Then there should be no parse errors

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@@@ Ruby
Given /^a Gherkin parser$/ do 
  @parser = Gherkin::Parser.new(@listener)
end

Given "the following text is parsed:" do |text|
  @parser.parse(text)
end

Then "there should be no parse errors" do
  @listener.errors.should == []
end

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• utf8_pack
• 1.8/1.9 and UTF8