anchor.diff:  Each test case follows the same structure:
   
   [source]
  +----
   test 'description of test' do
     # test logic
   end
  +----
   
   At the moment, the tests are quite primitive.
   Here's how a typical test operates:
  
positive.code: == Submitting a Pull Request
  
  . {fork-help-uri}[Fork the repository].
  . Run +bundle install+ to install dependencies.
  . {branch-help-uri}[Create a topic branch].
  . Add tests for your unimplemented feature or bug fix. (See <<writing-and-executing-tests>>)
  . Run +bundle exec rake+ to run the tests.
  If your tests pass, return to step 3.
  . Implement your feature or bug fix.
  . Run +bundle exec rake+ to run the tests.
  If your tests fail, return to step 5.
  . Add documentation for your feature or bug fix.
  . If your changes are not 100% documented, go back to step 7.
  
negative.code: = Contributing
  // settings:
  :idprefix:
  :idseparator: -
  :source-language: ruby
  :language: {source-language}
  // URIs:
  :repo-uri: https://github.com/asciidoctor/asciidoctor
  :base-help-uri: https://help.github.com/articles
  :issues-uri: {repo-uri}/issues
  