Add #to_envelope for gherkin document

CHANGELOG.md

@@ -9,6 +9,9 @@ This document is formatted according to the principles of [Keep A CHANGELOG](htt
 Please visit [cucumber/CONTRIBUTING.md](https://github.com/cucumber/cucumber/blob/master/CONTRIBUTING.md) for more info on how to contribute to Cucumber.
 
 ## [Unreleased]
+### Added
+- Added `#to_envelope` for `Cucumber::Core::Gherkin::Document` ([#329](https://github.com/cucumber/cucumber-ruby-core/pull/329))
+
 ### Changed
 - Refactored the internal base `Event` class to reduce complexity and make it more flexible for future use (No user facing changes)
 

lib/cucumber/core/gherkin/document.rb

@@ -7,17 +7,27 @@ class Document
         attr_reader :uri, :body, :language
 
         def initialize(uri, body, language = nil)
-          @uri      = uri
-          @body     = body
+          @uri = uri
+          @body = body
           @language = language || 'en'
         end
 
+        def ==(other)
+          to_s == other.to_s
+        end
+
         def to_s
           body
         end
 
-        def ==(other)
-          to_s == other.to_s
+        def to_envelope
+          Cucumber::Messages::Envelope.new(
+            source: Cucumber::Messages::Source.new(
+              uri: uri,
+              data: body,
+              media_type: 'text/x.cucumber.gherkin+plain'
+            )
+          )
         end
       end
     end