Only include React::Rails::TestHelper in test environment

[Aesthetikx]

Based on this discussion in the rails repository I determined that the latest version of react-rails (2.5.0, not present in 2.4.7) inadvertently causes action_controller/test_case to be required, which breaks ActionController::Live streaming in development and presumably production environments.

/home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/actionpack-5.2.3/lib/action_controller/test_case.rb:23:in `<module:Live>'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/actionpack-5.2.3/lib/action_controller/test_case.rb:18:in `<module:ActionController>'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/actionpack-5.2.3/lib/action_controller/test_case.rb:13:in `<top (required)>'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/actionpack-5.2.3/lib/action_dispatch/testing/integration.rb:614:in `<module:Behavior>'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/actionpack-5.2.3/lib/action_dispatch/testing/integration.rb:610:in `<class:IntegrationTest>'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/actionpack-5.2.3/lib/action_dispatch/testing/integration.rb:600:in `<module:ActionDispatch>'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/actionpack-5.2.3/lib/action_dispatch/testing/integration.rb:12:in `<top (required)>'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
  /home/john/.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/react-rails-2.5.0/lib/react/rails/railtie.rb:61:in `block (2 levels) in <class:Railtie>'

This change only includes React::Rails::TestHelper in the test environment.

[pcarn]

+1, this fixed my problem

[BookOfGreg]

Thank you for confirming this does not occur in the 2.4 branch, that helps me know there is no backport needed.
I'll look into why Chrome is breaking the test suite again, Google probably changed how the webdrivers work (again!) and then get this through as a point release as soon as I'm able to test it myself as the code and attached discussion seems sensible.
I remember copying that include code from another gem so yeah this is probably affecting a fair amount of the community.

[pcarn]

@BookOfGreg Can this be merged soon so we can use it? Thanks!

[BookOfGreg]

I need the ChromeDriver fix first. #1004
The tests won't run without it.
I'd love some help!

[BookOfGreg]

@Aesthetikx @pcarn I re-ran the tests with master merged (#1005 , Finished work on #1004 ) and tests passed there.

Released in 2.6.0

[kwstannard]

Noting here for posterity and search crawlers that this was a breaking change for us, causing a NoMethodError #flash on ActionDispatch::Request.

https://github.com/rails/rails/blob/v5.2.6/actionpack/lib/action_controller/metal/request_forgery_protection.rb#L170

We were able to just remove csrf protection on our API controllers to get around the failure as I am under the impression that csrf is not needed for APIs.

I consider this to be a problem with Rails though. It is not reasonable to expect this change to have caused that error.