Controller tests no longer accept ActionDispatch::Http::UploadedFile

[kirs]

In the process of upgrading to Rails 5, I've discovered a piece of code that worked fine on 4.2 and no longer works on 5-0-stable:

class PostsController < ApplicationController
  def upload
    raise "content: #{params[:file]}, class: #{params[:file].class}"
  end
end

class PostsControllerTest < ActionController::TestCase
  test "upload" do
    artwork = ActionDispatch::Http::UploadedFile.new(
      filename: 'artwork.jpeg',
      content_type: 'image/jpeg',
      tempfile: StringIO.new,
    )

    post :upload, params: { file: artwork }
  end
end

$ rails test test/controllers/posts_controller_test.rb
# Running:
Error:
PostsControllerTest#test_upload:
RuntimeError: content: #<ActionDispatch::Http::UploadedFile:0x007fb0c877acd8>, class: String
    app/controllers/posts_controller.rb:16:in `upload'
    test/controllers/posts_controller_test.rb:18:in `block in <class:PostsControllerTest>'

As you see, submitting a form with ActionDispatch::Http::UploadedFile instance gets the upload casted to String.

The reason why it happens is here: https://github.com/rails/rails/blob/5-0-stable/actionpack/lib/action_controller/test_case.rb#L137

It makes sense that Rails 5 is expecting Rack::Test::UploadedFile in test env, but I think that we shouldn't have break code that worked on 4.2. It seems like a regression to me.

cc @tenderlove since you've introduced that line.

[kirs]

The reason why I cannot use Rack::Test::UploadedFile in my test suite is that it only accepts a path to real file. In my test case, I want to test how the controller behaves with an empty file (ActionDispatch::Http::UploadedFile.new(tempfile: StringIO.new))

[maclover7]

👍 Makes sense to me, can you open up a PR?

[kirs]

@maclover7 I had a chat with @rafaelfranca and it turns out that we can't send a valid file just with StringIO.new, because upload should also contain filename and mime type.

I'm going to close the issue.

[jaredbeck]

Using ::Rack::Test::UploadedFile instead of ::ActionDispatch::Http::UploadedFile worked for me, thanks. The constructor is a bit different, but no problem.

It would be great if someone could add this to the upgrade guide:
http://guides.rubyonrails.org/upgrading_ruby_on_rails.html#upgrading-from-rails-4-2-to-rails-5-0

[maclover7]

@jaredbeck opened #27954

[sergey-alekseev]

@maclover7 @jaredbeck can you explain why you added

If you are using ActionDispatch::Http::UploadedFile in your tests to upload files, you will need to change to use the similar Rack::Test::UploadedFile class instead.

to the "Upgrading from Rails 4.2 to Rails 5.0" guide?

ActionDispatch::Http::UploadedFile works fine with a real file. As @kirs mentioned above

we can't send a valid file just with StringIO.new, because upload should also contain filename and mime type

As I understand that's the reason of the issue and that's why he closed it. Correct me if I'm wrong.