Add examples of tests using the Rule keyword

Note: the writer tests is currently disabled, not sure this is really needed.

Author: vincent-psarga

lib/cucumber/core/gherkin/writer.rb

@@ -48,7 +48,7 @@ class Feature
 
           default_keyword 'Feature'
 
-          elements :background, :scenario, :scenario_outline
+          elements :background, :rule, :scenario, :scenario_outline
 
           def build(source = [])
             elements.inject(source + statements) { |acc, el| el.build(acc) + [NEW_LINE] }
@@ -89,6 +89,24 @@ def statements
           end
         end
 
+        class Rule
+          include HasElements
+          include HasOptionsInitializer
+          include HasDescription
+          include Indentation.level 2
+
+          default_keyword 'Rule'
+
+          elements :scenario
+
+          private
+          def statements
+            prepare_statements comments_statement,
+              name_statement,
+              description_statement
+          end
+        end
+
         class Scenario
           include HasElements
           include HasOptionsInitializer

spec/cucumber/core/gherkin/parser_spec.rb

@@ -89,6 +89,44 @@ def self.source(&block)
           end
         end
 
+        context "when scenario is inside a rule" do
+          source do
+            feature do
+              rule do
+                scenario do
+                  step 'text'
+                end
+              end
+            end
+          end
+
+          it "passes on the pickle" do
+            expect( receiver ).to receive(:pickle)
+            parse
+          end
+        end
+
+        context "when there are multiple rules and scenarios" do
+          source do
+            feature do
+              rule do
+                scenario do
+                  step 'text'
+                end
+              end
+              rule do
+                scenario do
+                  step 'text'
+                end
+              end
+            end
+          end
+
+          it "passes on the pickles" do
+            expect( receiver ).to receive(:pickle).twice
+            parse
+          end
+        end
       end
     end
   end

spec/cucumber/core/gherkin/writer_spec.rb

@@ -233,6 +233,27 @@ module Cucumber::Core::Gherkin
           end
         end
       end
+
+      context 'with rules' do
+        xit 'can have a description' do
+          source = gherkin do
+            feature do
+              rule name: "Simple", description: "My castle, my rule" do
+                scenario name: "My scenario"
+              end
+            end
+          end
+
+          expect( source.body ).to eq <<-END.unindent
+          Feature:
+
+            Rule: Simple
+              My castle, my rules
+
+              Scenario: My scenario
+          END
+        end
+      end
     end
 
     it 'generates a complex feature' do