Add feature for CoffeeScript support (close #29)

features/coffeescript_support.feature

@@ -0,0 +1,11 @@
+Feature: CoffeeScript support
+  In order to use the JS dialect I'm most comfortable with
+  As a step definition implementor
+  I want to use CoffeeScript for writing step definitions
+
+  Scenario: CoffeeScript step definition
+    Given a mapping written in CoffeeScript
+    When Cucumber executes a scenario using that mapping
+    Then the feature passes
+    And the mapping is run
+

features/step_definitions/cucumber_js_mappings.rb

@@ -1,6 +1,7 @@
 module CucumberJsMappings
-  STEP_DEFINITIONS_FILE = "features/step_definitions/cucumber_steps.js"
-  FEATURE_FILE          = "features/a_feature.feature"
+  STEP_DEFINITIONS_FILE          = "features/step_definitions/cucumber_steps.js"
+  COFFEE_SCRIPT_DEFINITIONS_FILE = "features/step_definitions/cucumber_steps.coffee"
+  FEATURE_FILE                   = "features/a_feature.feature"
 
   attr_accessor :support_code
 
@@ -112,6 +113,18 @@ def write_main_step_definitions_file
     append_to_file(STEP_DEFINITIONS_FILE, "};\nmodule.exports = stepDefinitions;")
   end
 
+  def write_coffee_script_definition_file
+    append_to_file COFFEE_SCRIPT_DEFINITIONS_FILE, <<-EOF
+fs = require('fs')
+stepDefinitions = () ->
+  this.defineStep(/^a mapping$/, (callback) ->
+    fs.writeFileSync('a_mapping.step', '')
+    callback()
+  )
+module.exports = stepDefinitions
+EOF
+  end
+
   def get_file_contents(file_path)
     file_realpath = File.expand_path(file_path, File.dirname(__FILE__))
     File.open(file_realpath, 'rb') do |f|

features/step_definitions/cucumber_steps.rb

@@ -0,0 +1,19 @@
+# This file contains step definitions which are relevant to
+# Cucumber.js feature suite only.
+
+Given /^a mapping written in CoffeeScript$/ do
+  write_coffee_script_definition_file
+end
+
+When /^Cucumber executes a scenario using that mapping$/ do
+  write_feature <<-EOF
+Feature:
+  Scenario:
+    Given a mapping
+EOF
+  run_feature
+end
+
+Then /^the mapping is run$/ do
+  assert_passed "a mapping"
+end