No Joy for Cucumber on V8

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Up tonight, I'd like to see if I can write some Cucumber scenarios in the v8 Javascript engine. Joseph Wilk recently wrote a blog post on how to do this, so hopefully it will prove straight forward.

I install therubyracer gem as normal:

gem install therubyracer

I also checkout the latest version of cucumber to be sure that I have the recent javascript bindings. The javascript example are located in the examples/javascript directory, along with a Rakefile to run them. Unfortunately, when I do run the examples, I find:

/home/cstrom/.rvm/rubies/ruby-1.8.7-p249/bin/ruby -I "/home/cstrom/repos/cuke.real/lib:lib" "/home/cstrom/repos/cuke.real/bin/cucumber" 
Uncaught Error: undefined method `ToString' for #: /home/cstrom/repos/cuke.real/bin/../lib/cucumber/js_support/js_dsl.js:12 (V8::JavascriptError)
/home/cstrom/.rvm/gems/ruby-1.8.7-p249/gems/therubyracer-0.7.0/lib/v8/context.rb:33:in `eval'
/home/cstrom/.rvm/gems/ruby-1.8.7-p249/gems/therubyracer-0.7.0/lib/v8/context.rb:38:in `evaluate'
/home/cstrom/.rvm/gems/ruby-1.8.7-p249/gems/therubyracer-0.7.0/lib/v8/context.rb:43:in `load'
/home/cstrom/.rvm/gems/ruby-1.8.7-p249/gems/therubyracer-0.7.0/lib/v8/context.rb:42:in `open'
/home/cstrom/.rvm/gems/ruby-1.8.7-p249/gems/therubyracer-0.7.0/lib/v8/context.rb:42:in `load'
/home/cstrom/repos/cuke.real/bin/../lib/cucumber/js_support/js_language.rb:31:in `send'
/home/cstrom/repos/cuke.real/bin/../lib/cucumber/js_support/js_language.rb:31:in `method_missing'
/home/cstrom/repos/cuke.real/bin/../lib/cucumber/js_support/js_language.rb:117:in `load_code_file'
/home/cstrom/repos/cuke.real/bin/../lib/cucumber/step_mother.rb:84:in `load_code_file'
/home/cstrom/repos/cuke.real/bin/../lib/cucumber/step_mother.rb:76:in `load_code_files'
/home/cstrom/repos/cuke.real/bin/../lib/cucumber/step_mother.rb:75:in `each'
/home/cstrom/repos/cuke.real/bin/../lib/cucumber/step_mother.rb:75:in `load_code_files'
/home/cstrom/repos/cuke.real/bin/../lib/cucumber/cli/main.rb:56:in `execute!'
/home/cstrom/repos/cuke.real/bin/../lib/cucumber/cli/main.rb:25:in `execute'
/home/cstrom/repos/cuke.real/bin/cucumber:8
rake aborted!
Command failed with status (1): [/home/cstrom/.rvm/rubies/ruby-1.8.7-p249/b...]

(See full trace by running task with --trace)

I am not sure what the deal is with the capital ToString. Converting it to toString has no effect. Converting it to to_s has some effect, but not enough. Eventually, I happen across an issue opened by Corey Haines on therubyracer's github issue tracker. Nice! That is the same backtrace I am getting and the problem looks to be solved by Charles Lowell himself.

After checking out Charles's fork of Cucumber, I am able to run the Cucumber feature, but the fibonnaci function seems to always return an empty array:

  @fibonacci
  Scenario Outline: Series                                 # features/fibonacci.feature:7
    When I ask Javascript to calculate fibonacci up to <n> # 
    Then it should give me <series>                        # 

    Examples:
      | n   | series                                 |
      | 1   | []                                     |
      Uncaught Expected <'[]'> but got <[]>: features/support/env.js:3 (V8::JavascriptError)
      features/fibonacci.feature:9:in `Then it should give me <series>'
      | 2   | [1, 1]                                 |
      Uncaught Expected <'[1, 1]'> but got <[]>: features/support/env.js:3 (V8::JavascriptError)
      features/fibonacci.feature:9:in `Then it should give me <series>'
      | 3   | [1, 1, 2]                              |
      Uncaught Expected <'[1, 1, 2]'> but got <[]>: features/support/env.js:3 (V8::JavascriptError)
      features/fibonacci.feature:9:in `Then it should give me <series>'
      | 4   | [1, 1, 2, 3]                           |
      Uncaught Expected <'[1, 1, 2, 3]'> but got <[]>: features/support/env.js:3 (V8::JavascriptError)
      features/fibonacci.feature:9:in `Then it should give me <series>'
      | 6   | [1, 1, 2, 3, 5]                        | 
      Uncaught Expected <'[1, 1, 2, 3, 5]'> but got <[]>: features/support/env.js:3 (V8::JavascriptError)
      features/fibonacci.feature:9:in `Then it should give me <series>'
      | 9   | [1, 1, 2, 3, 5, 8]                     | 
      Uncaught Expected <'[1, 1, 2, 3, 5, 8]'> but got <[]>: features/support/env.js:3 (V8::JavascriptError)
      features/fibonacci.feature:9:in `Then it should give me <series>'
      | 100 | [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89] | 
      Uncaught Expected <'[1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]'> but got <[]>: features/support/env.js:3 (V8::JavascriptError)
      features/fibonacci.feature:9:in `Then it should give me <series>'

This one has me stumped, unfortunately. The problem seems to be with the fibonnaci number passed into the scenario. It ought to be a string and mostly behaves like a string, but, when I throw the parseInt value

var fibonacciSeries = function(fibonacciLimit) {
  var result = Array();
  var currentfibonacciValue = fibonacci(1);
  var i = 2;
  throw " " + currentfibonacciValue + " " + fibonacciLimit + " " + typeof(fibonacciLimit) + " " + parseInt("" + fibonacciLimit.toString() + "", 10);
  while(currentfibonacciValue < parseInt(fibonacciLimit)) {
    result.push(currentfibonacciValue);
  throw result.join(",");

    currentfibonacciValue  = fibonacci(i);
    i++;
  }
//  result = [1,1];
  return "[" + result.join(", ") + "]";
}

I always end up with NaN:

 @fibonacci
  Scenario Outline: Series                                 # features/fibonacci.feature:7
    When I ask Javascript to calculate fibonacci up to <n> # 
    Then it should give me <series>                        # 

    Examples:
      | n   | series                                 |
      | 1   | []                                     |
      Uncaught  1 '1' string NaN: features/lib/fibonacci.js:9 (V8::JavascriptError)
      features/fibonacci.feature:8:in `When I ask Javascript to calculate fibonacci up to <n>'
      | 2   | [1, 1]                                 |
      Uncaught  1 '2' string NaN: features/lib/fibonacci.js:9 (V8::JavascriptError)
      features/fibonacci.feature:8:in `When I ask Javascript to calculate fibonacci up to <n>'
...

I am a bit disappointed to have to call it a night here. Tomorrow, I will pick it back up with fresh eyes and possibly look to install the pre-release version of therubyracer in the hopes of resolving this.


Day #122