Move change category detection to a helper

danger/documentation/Dangerfile

 # frozen_string_literal: true
 
-# All the files/directories that should be reviewed by the Docs team.
-DOCS_FILES = [
-  'doc/'
-].freeze
-
-def docs_paths_requiring_review(files)
-  files.select do |file|
-    DOCS_FILES.any? { |pattern| file.start_with?(pattern) }
-  end
-end
-
-docs_paths_to_review = docs_paths_requiring_review(helper.all_changed_files)
+docs_paths_to_review =  helper.changes_by_category[:documentation]
 
 unless docs_paths_to_review.empty?
   message 'This merge request adds or changes files that require a ' \

danger/plugins/helper.rb

@@ -30,5 +30,22 @@ module Danger
         .to_a
         .sort
     end
+
+    # @return [Hash<String,Array<String>>]
+    def changes_by_category
+      all_changed_files.inject(Hash.new { |h, k| h[k] = [] }) do |hsh, file|
+        hsh[category_for_file(file)] << file
+      end
+    end
+
+    def category_for_file(file)
+      _, category = CATEGORIES.find { |regexp, _| regexp.match?(file) }
+
+      category || :unknown
+    end
+
+    CATEGORIES = {
+      %r{\Adoc/} => :documentation
+    }
   end
 end