Use Rails transactional tests

As of Rails 5.1:

  - Rails has built-in support for running tests within database
    transactions, so Database Cleaner is no longer needed for this.
  - Rails automatically shares the database connection across threads,
    so transactional_capybara is no longer needed.

Changes:

  - Enable `use_transactional_tests`.
  - Remove transactional_capybara.
  - Remove the Database Cleaner test wrapper.

This resolves:

  - transactional_capybara mismanages the shared database connection,
    causing the connection to falsely report as idle after the first
    test. At 6 minutes (idle_timeout + reaping_frequency) into testing,
    the connection is closed, causing e.g. `PG::ConnectionBad` errors.

Gemfile

@@ -242,7 +242,6 @@ group :test do
   gem 'database_cleaner'
   gem 'geckodriver-helper'
   gem 'rspec-rails'
-  gem 'transactional_capybara'
   gem 'webdrivers'
   # for measuring test coverage
   gem 'simplecov-cobertura'

Gemfile.lock

@@ -568,8 +568,6 @@ GEM
     thread_safe (0.3.6)
     tilt (2.0.9)
     timecop (0.9.1)
-    transactional_capybara (0.2.0)
-      capybara
     transitions (1.2.1)
     ttfunk (1.7.0)
     turbolinks (5.2.1)
@@ -714,7 +712,6 @@ DEPENDENCIES
   stripe
   stripe-ruby-mock
   timecop
-  transactional_capybara
   transitions
   turbolinks
   uglifier (>= 1.3.0)

spec/features/commercials_spec.rb

@@ -85,7 +85,6 @@ feature Commercial do
       click_button 'Update'
       page.find('#flash')
       expect(flash).to eq('Commercial was successfully updated.')
-      TransactionalCapybara::AjaxHelpers.wait_for_ajax(page)
       expect(event.commercials.count).to eq(1)
       commercial.reload
       expect(commercial.url).to eq('https://www.youtube.com/watch?v=M9bq_alk-sw')
@@ -118,7 +117,6 @@ feature Commercial do
       end
       page.find('#flash')
       expect(flash).to eq('Commercial was successfully destroyed.')
-      TransactionalCapybara::AjaxHelpers.wait_for_ajax(page)
       expect(event.commercials.count).to eq(0)
     end
   end

spec/features/proposals_spec.rb

@@ -138,7 +138,6 @@ feature Event do
 
       page.find('#flash')
       expect(page).to have_content 'Proposal was successfully submitted.'
-      TransactionalCapybara::AjaxHelpers.wait_for_ajax(page)
       expect(current_path).to eq(conference_program_proposals_path(conference.short_title))
       expect(Event.count).to eq(expected_count)
     end

spec/features/versions_spec.rb

@@ -392,7 +392,7 @@ feature 'Version' do
     click_link 'Comments (0)'
     fill_in 'comment_body', with: 'Sample comment'
     click_button 'Add Comment'
-    TransactionalCapybara::AjaxHelpers.wait_for_ajax(page)
+    expect(page).to have_text('Comments (1)')
     Comment.last.destroy
     PaperTrail::Version.last.reify.save
 

spec/spec_helper.rb

@@ -20,9 +20,6 @@ require 'webdrivers'
 # all migrations applied
 ActiveRecord::Migration.maintain_test_schema!
 
-# Keep capybara and the database on the same page
-require 'transactional_capybara/rspec'
-
 # Adds rspec helper provided by paper_trail
 # makes it easier to control when PaperTrail is enabled during testing.
 require 'paper_trail/frameworks/rspec'
@@ -49,10 +46,8 @@ RSpec.configure do |config|
   # config.mock_with :flexmock
   # config.mock_with :rr
 
-  # If you're not using ActiveRecord, or you'd prefer not to run each of your
-  # examples within a transaction, remove the following line or assign false
-  # instead of true.
-  config.use_transactional_fixtures = false
+  # Test within database transactions
+  config.use_transactional_examples = true
 
   # Run specs in random order to surface order dependencies. If you find an
   # order dependency and want to debug it, you can fix the order by providing

spec/support/database_cleaner.rb

@@ -5,13 +5,4 @@ RSpec.configure do |config|
     DatabaseCleaner.clean_with(:truncation)
     Rails.application.load_seed
   end
-
-  config.before(:each) do
-    DatabaseCleaner.start
-  end
-
-  config.after(:each) do |example|
-    TransactionalCapybara::AjaxHelpers.wait_for_ajax(page) if example.metadata[:js]
-    DatabaseCleaner.clean
-  end
 end