Rspec fails after Rails version update

I got into a new project that hasn't been touched for a couple of years prior, the clients want me and my team to update Ruby/Rails from Rails 4 to the newest possible version without breaking the way the product works.

After an update to Rails 5 however, about a third of the Rspec tests started breaking. Most of those were easily solvable, but I can't find any information if somebody has encountered an error like that in the past.

The error itself is:

Data Transfer Results renders data transfer results details page
Failure/Error: get "/data_transfer_results/#{dtr.id}"
NoMethodError:
undefined method `empty?' for #<ActionDispatch::Http::Headers:0x0000559e8ac09a08>
# ./spec/requests/data_transfer_results_spec.rb:15:in `block (2 levels) in <top (required)>'
# ./spec/rails_helper.rb:107:in `block (3 levels) in <top (required)>'
# ./spec/rails_helper.rb:106:in `block (2 levels) in <top (required)>'

The test that fails contains the following:

require "rails_helper"

RSpec.describe "API Monitoring", :type => :request do
  it "renders the index template" do
    sign_in create(:user, name: 'John Doe')
    get "/api_monitoring"
    expect(response).to render_template(:index)
    expect(response.body).to include('API Monitoring')
  end
end

I suspect that this might be due to some outdated dependencies or version mismatches, but am not 100% sure.

The updated Gemfile looks like this:

source 'https://rubygems.org'
gem 'pry'
gem 'aasm', '~> 5.0'
gem 'airbrake'
gem 'american_date'
gem "audited", "~> 4.8"
gem 'aws-sdk', '~> 2.0'
gem 'better_errors', '~> 2.5.1', group: :development
gem 'binding_of_caller', '~> 0.8.0', group: :development
gem 'byebug'
gem 'capistrano', '~> 3.7'
gem 'capistrano-bundler', '~> 1.4'
gem 'capistrano-passenger'
gem 'capistrano-rails', '~> 1.4'
gem 'capistrano-rbenv', '~> 2.1'
gem 'capistrano3-delayed-job', '~> 1.0'
gem 'capybara', group: [:development, :test]
gem 'capybara-screenshot', group: [:development, :test]
gem 'chosen-rails'
gem 'compass-rails', '3.1.0'
gem 'cucumber-rails', require: false, group: [:development, :test]
gem 'daemons'
gem 'database_cleaner', group: [:development, :test]
gem 'ddtrace'
gem 'delayed_job_active_record'
gem 'devise', '~> 4.7.3'
gem 'devise-async', git: 'https://github.com/mhfs/devise-async.git', ref: '177f6363a002f7ff28f1d289c8cab7ad8d9cb8c5'
gem 'devise-security'
gem 'factory_girl_rails', group: [:development, :test]
gem 'faker', group: [:development, :test, :staging]
gem 'fixedwidth', git: 'https://github.com/gristmill/fixedwidth.git', ref: '82575c2d6faa2d1aa82158147c5268f0d4f673bd'
gem 'fog-aws'
gem 'httparty'
gem 'jbuilder', '~> 2.7'
gem 'jquery-rails'
gem 'jquery-turbolinks'
gem 'launchy', group: [:development, :test]
gem 'lograge'
gem 'logstash-event'
gem 'mysql2', '>= 0.4.4', '< 0.6.0'
gem 'net-sftp'
gem 'omniauth-azure-activedirectory'
gem 'omniauth-saml'
gem 'paperclip', '~> 6.1'
gem 'poltergeist', group: [:development, :test]
gem 'rails', '5.2.8'
gem 'rails-erd'
gem 'rspec-rails', '> 3.10', group: [:development, :test]
gem 'ruby-kafka'
gem 'sass-rails', '~> 5.0'
gem 'sdoc', '~> 1.0', group: :doc
gem 'select2-rails'
gem 'simplecov', require: false, group: :test
#gem 'psych', '5.1.0'
gem 'skylight'
#gem 'skylight' #, '~> 5.0.1'
gem 'spring', group: :development
gem 'stupidedi'
gem 'timecop', group: :test
gem 'thread_safe'
gem 'trix'
gem 'validates_timeliness'
gem 'puma', '~> 5.6'
gem 'chronic'
gem 'after_commit_everywhere', '~> 1.0'

Maybe this is some internal call what we'd have to fix ourselves or just update some of the dependencies? We are not sure, so any help will be greatly appreciated!

Please, keep in mind that this is legacy client code and almost everything in the project is at least 4-5 years old.

The project is very old, and as such it uses an extremely old dependency that's a fork of a 2011 version of the stupidedi gem.

In it, there are some extension methods in the lib/ruby/blank.rb file:

module Enumerable

  # True if the collection is `empty?`
  #
  # @example
  #   [1,2].blank?    #=> false
  #   [].blank?       #=> false
  #
  def blank?
    empty?
  end

  def present?
    not empty?
  end
end

The thing that was breaking the application (e.g. causing the error) was the not empty? clause.

Please, not that this is very outdated and the current version of the gem doesn't do such stupid things.

Moral of the story: Check for method overrides in the application and related forks/extensions/private libs.

rspec-rails 3.x is for Rails versions < 5.0. Upgrade your version of rspec-rails to a compatible version:

> rspec-rails 6.x for Rails 6.1 or 7.x.
>
> rspec-rails 5.x for Rails 5.2 or 6.x.
>
> rspec-rails 4.x for Rails from 5.x or 6.x.
>
> rspec-rails 3.x for Rails earlier than 5.0.
>
> rspec-rails 1.x for Rails 2.x.

I'm not saying that this will resolve this issue but it's important that you ensure compatibility of the gems that you're using before you start debugging these issues otherwise you're going to be wasting a lot of time. You need to validate that you're using compatible versions for every single gem in the Gemfile.

As for the error:

> undefined method `empty?' for #<ActionDispatch::Http::Headers:0x0000559e8ac09a08>

It's important to note that ActionDispatch::Http::Headers does not have an .empty? method in Rails 4 or in any subsequent version. You should check that the spec actually passes under Rails 4. I suspect that it doesn't but it's impossible to tell because you've rendered the stack trace meaningless by not indicating which line is line 15 in the spec that you posted.