Fix tests for Ruby 1.8.7.
Fix tests for Ruby 1.8.7.

kerrizor/rails-erd,sferik/rails-erd,sferik/rails-erd,voormedia/rails-erd,voormedia/rails-erd,mallikarjunayaddala/rails-erd,qiujuer/rails-erd,nalabjp/rails-erd,asux/rails-erd,mallikarjunayaddala/rails-erd,kerrizor/rails-erd,nalabjp/rails-erd,qiujuer/rails-erd