[Fix #1794] Check if there are tokens before accessing them

[schmijos]

This PR fixes a problem occurring if rubocop scans empty files containing only new lines (#1794). I extracted the function determining the __END__ token into an own method which respects empty token lists.

I'm not sure what to expect from autocorrection though.

[jonas054]

You should expect autocorrect to give ['', ''].join("\n") for EnforcedStyle: final_newline and ['', '', ''].join("\n") for EnforcedStyle: final_blank_line, so please add those examples.

Could you also add an example for a file containing only newlines and __END__? I know it's a weird case, but it's possible so we should support it.

[bbatsov]

Squash the commits into one and mention the bugfix in the changelog.

[schmijos]

@bbatsov Do you know what's wrong with the build? Running bundle exec rspec && bundle exec rubocop on my local machine results in all green.

[jonas054]

The same error exists on master. It seems that the Documentation cop doesn't work with parser 2.2.2.0. You can reproduce the error locally if you run bundle update first.

[bbatsov]

Rebase this on top of the current master.

[bbatsov]

Ah, you'll need to rebase again unfortunately.

[schmijos]

Ok, did it.

[bbatsov]

👍 Thanks!