dry-run error :: can't dup NilClass (TypeError)

[sgreen-r7]

I already found the cause to this error, however I just wanted to post this here incase anybody else comes across the same issue. After the upgrade from cucumber 2.3.3 to 2.4.0 I ran into the error/stacktrace below. The culprit scenario file had not be changed and started failing only after the upgrade to 2.4.0, and was found during a --dry-run.

code:ruby
Scenario Outline: Lorem ipsum dolor sit amet
Given consectetur adipiscing elit
When proin non varius est <page_size> maecenas eu magna tempus
Then consectetur nibh eu, cursus diam maecenas

Examples:
Examples:
  |page_size |page   |count |
  | 5        |  1    | 5    |
  | 10       |  2    | 10   |
  | 25       |  1    | 25   |

The error happens due to `Examples:` being listed twice for the `Scenario Outline`. And again I bring this up because we were not getting this error prior to upgrading to cucumber 2.4.0. 

Env: `ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin13]`
Command: `bundle exec cucumber --dry-run`
Error: `can't dup NilClass (TypeError)` 
Stacktrace:

``` code:ruby```
└─[2] <git:(master 7c34199✱✈) $> cucumber --dry-run
can't dup NilClass (TypeError)
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:31:in `dup'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:31:in `initialize'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:308:in `new'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:308:in `initialize'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:274:in `new'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:274:in `block in initialize'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:274:in `map'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:274:in `initialize'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:133:in `new'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:133:in `block in initialize'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:126:in `map'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:126:in `initialize'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:105:in `new'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:105:in `feature'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/ast_builder.rb:16:in `feature'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core/gherkin/parser.rb:28:in `document'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core.rb:27:in `block in parse'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core.rb:26:in `each'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core.rb:26:in `parse'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-core-1.5.0/lib/cucumber/core.rb:18:in `compile'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-2.4.0/lib/cucumber/runtime.rb:67:in `run!'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-2.4.0/lib/cucumber/cli/main.rb:32:in `execute!'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/gems/cucumber-2.4.0/bin/cucumber:8:in `<top (required)>'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/bin/cucumber:23:in `load'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/bin/cucumber:23:in `<main>'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/bin/ruby_executable_hooks:15:in `eval'
/Users/sgreen/.rvm/gems/ruby-2.2.2@nexpose-cucumber/bin/ruby_executable_hooks:15:in `<main>'

[brasmusson]

As Gherkin v3.2.0 (used in Cucumber-Ruby v2.3.3) does not allow empty Examples: sections, one would expect that the above feature should trigger a parser error in Gherkin v3.2.0. But what really happens is that the second Examples: line is parsed as a description (ast node) to the first Examples: line.

With Gherkin v4.0.0 the feature file is now (correctly) parsed as a scenario outline with two Examples: sections, one completely empty (which is allowed in Gherkin v4.0.0) and one with an examples table in it. As Gherkin now is allowing different variants of incomplete scenario outline, Cucumber-Ruby must also handle those cases, but as this issue points out - it does not do that yet.

[lock]

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