nil was converted to "" and the matching regex would return [] and then be converted to nil with max usage.
Example exception:
```
NoMethodError (undefined method `<=' for nil:NilClass)
lib/text_sentinel.rb:71:in `seems_unpretentious?'
lib/validators/quality_title_validator.rb:13:in `validate_each'
lib/topic_creator.rb:25:in `valid?'
```
This change both speeds up specs (less strings to allocate) and helps catch
cases where methods in Discourse are mutating inputs.
Overall we will be migrating everything to use #frozen_string_literal: true
it will take a while, but this is the first and safest move in this direction
Since rspec-rails 3, the default installation creates two helper files:
* `spec_helper.rb`
* `rails_helper.rb`
`spec_helper.rb` is intended as a way of running specs that do not
require Rails, whereas `rails_helper.rb` loads Rails (as Discourse's
current `spec_helper.rb` does).
For more information:
https://www.relishapp.com/rspec/rspec-rails/docs/upgrade#default-helper-files
In this commit, I've simply replaced all instances of `spec_helper` with
`rails_helper`, and renamed the original `spec_helper.rb`.
This brings the Discourse project closer to the standard usage of RSpec
in a Rails app.
At present, every spec relies on loading Rails, but there are likely
many that don't need to. In a future pull request, I hope to introduce a
separate, minimal `spec_helper.rb` which can be used in tests which
don't rely on Rails.
Joffrey JAFFEUX
Sam Saffron
Erick Guan
Arpit Jalan
Guo Xiang Tan
Rafael dos Santos Silva
Andy Waite
Jeff Wong
Robin Ward
Luciano Sousa
Nathan Nontell
Neil Lalonde
Michael Brown
Régis Hanol
Gosha Arinich
Jeremy Banks
Alexander