tags shouldn't be used mutliple times for a scenario

README.md

@@ -36,6 +36,7 @@ Detailed usage within the [disable_tags](https://github.com/funkwerk/gherkin_lin
  - [missing test action](https://github.com/funkwerk/gherkin_lint/blob/master/features/missing_test_action.feature)
  - [missing verification](https://github.com/funkwerk/gherkin_lint/blob/master/features/missing_verification.feature)
  - [same tag for all scenarios](https://github.com/funkwerk/gherkin_lint/blob/master/features/same_tag_for_all_scenarios.feature)
+ - [tag used multiple times](https://github.com/funkwerk/gherkin_lint/blob/master/features/tag_used_multiple_times.feature)
  - [too clumsy](https://github.com/funkwerk/gherkin_lint/blob/master/features/too_clumsy.feature)
  - [too long step](https://github.com/funkwerk/gherkin_lint/blob/master/features/too_long_step.feature)
  - [too many different tags](https://github.com/funkwerk/gherkin_lint/blob/master/features/too_many_different_tags.feature)

Rakefile

@@ -11,7 +11,7 @@ end
 
 desc 'Publishes the Gem'
 task :push do
-  sh 'gem push gherkin_lint-0.5.0.gem'
+  sh 'gem push gherkin_lint-0.6.0.gem'
 end
 
 desc 'Checks ruby style'

features/tag_used_multiple_times.feature

@@ -0,0 +1,51 @@
+Feature: Tag Used Multiple Times
+  As a Business Analyst
+  I want to use tags just once
+  so that redundancy is minimized.
+
+  Background: Prepare Testee
+    Given a file named "lint.rb" with:
+      """
+      $LOAD_PATH << '../../lib'
+      require 'gherkin_lint'
+
+      linter = GherkinLint::GherkinLint.new
+      linter.enable %w(TagUsedMultipleTimes)
+      linter.analyze 'lint.feature'
+      exit linter.report
+
+      """
+
+  Scenario Outline: Tag used twice
+    Given a file named "lint.feature" with:
+      """
+      <feature tag>
+      Feature: Test
+        @tag <scenario tag>
+        Scenario: A
+      """
+    When I run `ruby lint.rb`
+    Then it should fail with exactly:
+      """
+      TagUsedMultipleTimes - Tag @tag used multiple times
+        lint.feature (4): Test.A
+
+      """
+
+    Examples: Invalid Tag Combinations
+      | feature tag | scenario tag |
+      | @tag        |              |
+      |             | @tag         |
+
+  Scenario: Just unique tags
+    Given a file named "lint.feature" with:
+      """
+      Feature: Test
+        @tag_a @tag_b
+        Scenario: A
+      """
+    When I run `ruby lint.rb`
+    Then it should pass with exactly:
+      """
+
+      """

gherkin_lint.gemspec

@@ -1,7 +1,7 @@
 Gem::Specification.new do |s|
   s.name        = 'gherkin_lint'
-  s.version     = '0.5.0'
-  s.date        = '2016-08-31'
+  s.version     = '0.6.0'
+  s.date        = '2016-10-14'
   s.summary     = 'Gherkin Lint'
   s.description = 'Lint Gherkin Files'
   s.authors     = ['Stefan Rohe']

lib/gherkin_lint.rb

@@ -18,6 +18,7 @@
 require 'gherkin_lint/linter/missing_test_action'
 require 'gherkin_lint/linter/missing_verification'
 require 'gherkin_lint/linter/same_tag_for_all_scenarios'
+require 'gherkin_lint/linter/tag_used_multiple_times'
 require 'gherkin_lint/linter/too_clumsy'
 require 'gherkin_lint/linter/too_long_step'
 require 'gherkin_lint/linter/too_many_different_tags'
@@ -52,6 +53,7 @@ class GherkinLint
       InvalidFileName,
       InvalidStepFlow,
       SameTagForAllScenarios,
+      TagUsedMultipleTimes,
       TooClumsy,
       TooManyDifferentTags,
       TooManySteps,

lib/gherkin_lint/linter/tag_used_multiple_times.rb

@@ -0,0 +1,21 @@
+require 'gherkin_lint/linter'
+
+module GherkinLint
+  # service class to lint for tags used multiple times
+  class TagUsedMultipleTimes < Linter
+    def lint
+      scenarios do |file, feature, scenario|
+        references = [reference(file, feature, scenario)]
+        total_tags = tags(feature) + tags(scenario)
+        double_used_tags = total_tags.find_all { |a| total_tags.count(a) > 1 }.uniq!
+        next if double_used_tags.nil?
+        add_error(references, "Tag #{double_used_tags.join(' and ')} used multiple times")
+      end
+    end
+
+    def tags(element)
+      return [] unless element.include? :tags
+      element[:tags].map { |a| a[:name] }
+    end
+  end
+end