diff --git a/.circleci/config.yml b/.circleci/config.yml
index 7deedd7..2fd7722 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -1,31 +1,52 @@
 version: 2.1
 
 orbs:
+  # Required for feature specs.
+  browser-tools: circleci/browser-tools@1.1
+
   # Always take the latest version of the orb, this allows us to
   # run specs against Solidus supported versions only without the need
   # to change this configuration every time a Solidus version is released
   # or goes EOL.
   solidusio_extensions: solidusio/extensions@volatile
 
-  browser-tools: circleci/browser-tools@1.1
-
 jobs:
+  run-specs-with-sqlite:
+    executor:
+      name: solidusio_extensions/sqlite
+      ruby_version: "3.0"
+    steps:
+      - browser-tools/install-chrome
+      - solidusio_extensions/run-tests
   run-specs-with-postgres:
-    executor: solidusio_extensions/postgres
+    executor:
+      name: solidusio_extensions/postgres
+      ruby_version: "3.0"
     steps:
-      - browser-tools/install-browser-tools
+      - browser-tools/install-chrome
       - solidusio_extensions/run-tests
   run-specs-with-mysql:
-    executor: solidusio_extensions/mysql
+    executor:
+      name: solidusio_extensions/mysql
+      ruby_version: "3.0"
     steps:
-      - browser-tools/install-browser-tools
+      - browser-tools/install-chrome
       - solidusio_extensions/run-tests
+  lint-code:
+    executor:
+      name: solidusio_extensions/sqlite-memory
+      ruby_version: "3.0"
+    steps:
+      - solidusio_extensions/lint-code
 
 workflows:
   "Run specs on supported Solidus versions":
     jobs:
+      - run-specs-with-sqlite
       - run-specs-with-postgres
       - run-specs-with-mysql
+      - lint-code
+
   "Weekly run specs against master":
     triggers:
       - schedule:
@@ -35,5 +56,6 @@ workflows:
               only:
                 - master
     jobs:
+      - run-specs-with-sqlite
       - run-specs-with-postgres
       - run-specs-with-mysql
diff --git a/.github/stale.yml b/.github/stale.yml
index d9f6563..0d0b1c9 100644
--- a/.github/stale.yml
+++ b/.github/stale.yml
@@ -1,17 +1 @@
-# Number of days of inactivity before an issue becomes stale
-daysUntilStale: 60
-# Number of days of inactivity before a stale issue is closed
-daysUntilClose: 7
-# Issues with these labels will never be considered stale
-exemptLabels:
-  - pinned
-  - security
-# Label to use when marking an issue as stale
-staleLabel: wontfix
-# Comment to post when marking an issue as stale. Set to `false` to disable
-markComment: >
-  This issue has been automatically marked as stale because it has not had
-  recent activity. It will be closed if no further activity occurs. Thank you
-  for your contributions.
-# Comment to post when closing a stale issue. Set to `false` to disable
-closeComment: false
\ No newline at end of file
+_extends: .github
diff --git a/.github_changelog_generator b/.github_changelog_generator
new file mode 100644
index 0000000..eac0962
--- /dev/null
+++ b/.github_changelog_generator
@@ -0,0 +1,2 @@
+issues=false
+exclude-labels=infrastructure
diff --git a/.gitignore b/.gitignore
index bcd4aea..753f083 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,3 +14,7 @@ pkg
 *.swp
 spec/dummy
 spec/examples.txt
+Gemfile-local
+/sandbox
+.rvmrc
+.ruby-gemset
diff --git a/.rubocop.yml b/.rubocop.yml
index 6207a64..ed101eb 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,2 +1,7 @@
+inherit_from: .rubocop_todo.yml
+
 require:
   - solidus_dev_support/rubocop
+
+AllCops:
+  NewCops: disable
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
new file mode 100644
index 0000000..5079dfa
--- /dev/null
+++ b/.rubocop_todo.yml
@@ -0,0 +1,11 @@
+Layout/ArgumentAlignment:
+  Enabled: false
+
+RSpec/DescribeClass:
+  Enabled: false
+
+Style/MissingRespondToMissing:
+  Enabled: false
+
+Style/ClassAndModuleChildren:
+  Enabled: false
diff --git a/Gemfile b/Gemfile
index 69a2b47..d9777fb 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,14 +3,17 @@
 source 'https://rubygems.org'
 git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
-branch = ENV.fetch('SOLIDUS_BRANCH', 'master')
-solidus_git, solidus_frontend_git = if (branch == 'master') || (branch >= 'v3.2')
-                                      %w[solidusio/solidus solidusio/solidus_frontend]
-                                    else
-                                      %w[solidusio/solidus] * 2
-                                    end
-gem 'solidus', github: solidus_git, branch: branch
-gem 'solidus_frontend', github: solidus_frontend_git, branch: branch
+branch = ENV.fetch('SOLIDUS_BRANCH', 'main')
+gem 'solidus', github: 'solidusio/solidus', branch: branch
+
+# The solidus_frontend gem has been pulled out since v3.2
+if branch >= 'v3.2'
+  gem 'solidus_frontend'
+elsif branch == 'main'
+  gem 'solidus_frontend', github: 'solidusio/solidus_frontend', branch: branch
+else
+  gem 'solidus_frontend', github: 'solidusio/solidus', branch: branch
+end
 
 # Needed to help Bundler figure out how to resolve dependencies,
 # otherwise it takes forever to resolve them.
@@ -20,7 +23,7 @@ gem 'rails', '>0.a'
 # Provides basic authentication functionality for testing parts of your engine
 gem 'solidus_auth_devise'
 
-case ENV['DB']
+case ENV.fetch('DB', nil)
 when 'mysql'
   gem 'mysql2'
 when 'postgresql'
@@ -29,8 +32,16 @@ else
   gem 'sqlite3'
 end
 
+# While we still support Ruby < 3 we need to workaround a limitation in
+# the 'async' gem that relies on the latest ruby, since RubyGems doesn't
+# resolve gems based on the required ruby version.
+gem 'async', '< 3' if Gem::Version.new(RUBY_VERSION) < Gem::Version.new('3')
+
 gemspec
 
 # Use a local Gemfile to include development dependencies that might not be
-# relevant for the project or for other contributors, e.g.: `gem 'pry-debug'`.
-eval_gemfile 'Gemfile-local' if File.exist? 'Gemfile-local'
+# relevant for the project or for other contributors, e.g. pry-byebug.
+#
+# We use `send` instead of calling `eval_gemfile` to work around an issue with
+# how Dependabot parses projects: https://github.com/dependabot/dependabot-core/issues/1658.
+send(:eval_gemfile, 'Gemfile-local') if File.exist? 'Gemfile-local'
diff --git a/Rakefile b/Rakefile
index c08aa46..4e3773f 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 
+require 'bundler/gem_tasks'
 require 'solidus_dev_support/rake_tasks'
 SolidusDevSupport::RakeTasks.install
 
diff --git a/app/decorators/controllers/solidus_print_invoice/spree/admin/orders_controller_decorator.rb b/app/decorators/controllers/solidus_print_invoice/spree/admin/orders_controller_decorator.rb
index f874a69..3190a32 100644
--- a/app/decorators/controllers/solidus_print_invoice/spree/admin/orders_controller_decorator.rb
+++ b/app/decorators/controllers/solidus_print_invoice/spree/admin/orders_controller_decorator.rb
@@ -16,9 +16,11 @@ def show
           respond_with(@order) do |format|
             format.pdf do
               template = params[:template] || "invoice"
-              if (template == "invoice") && ::Spree::PrintInvoice::Config.use_sequential_number? && @order.invoice_number.blank?
+              if (template == "invoice") &&
+                 ::Spree::PrintInvoice::Config.use_sequential_number? &&
+                 @order.invoice_number.blank?
                 @order.invoice_number = ::Spree::PrintInvoice::Config.increase_invoice_number
-                @order.invoice_date = Date.today
+                @order.invoice_date = Time.zone.today
                 @order.save!
               end
               render layout: false, template: "spree/admin/orders/#{template}", formats: [:pdf], handlers: [:prawn]
diff --git a/app/helpers/spree/admin/print_invoice_helper.rb b/app/helpers/spree/admin/print_invoice_helper.rb
index 92812e4..95ec423 100644
--- a/app/helpers/spree/admin/print_invoice_helper.rb
+++ b/app/helpers/spree/admin/print_invoice_helper.rb
@@ -4,7 +4,9 @@ module Spree
   module Admin
     module PrintInvoiceHelper
       def font_faces
-        fonts = Prawn::Font::AFM::BUILT_INS.reject { |f| f =~ /zapf|symbol|bold|italic|oblique/i }.map { |f| [f.tr('-', ' '), f] }
+        fonts = Prawn::Font::AFM::BUILT_INS.reject do |f|
+          f =~ /zapf|symbol|bold|italic|oblique/i
+        end.map { |f| [f.tr('-', ' '), f] }
         options_for_select(fonts, Spree::PrintInvoice::Config[:print_invoice_font_face])
       end
 
diff --git a/app/models/spree/print_invoice_configuration.rb b/app/models/spree/print_invoice_configuration.rb
index faffc8d..4cc6040 100644
--- a/app/models/spree/print_invoice_configuration.rb
+++ b/app/models/spree/print_invoice_configuration.rb
@@ -14,7 +14,7 @@ class PrintInvoiceConfiguration < Preferences::Configuration
                  'logo/solidus_logo.png'
                else
                  Spree::Config[:admin_interface_logo]
-                  end
+               end
 
     preference :print_invoice_logo_scale, :integer, default: 50
     preference :print_invoice_font_face, :string, default: 'Helvetica'
diff --git a/bin/rails b/bin/rails
index c535fd2..6dbbbc3 100755
--- a/bin/rails
+++ b/bin/rails
@@ -1,15 +1,7 @@
 #!/usr/bin/env ruby
 
-# frozen_string_literal: true
-
-app_root = 'spec/dummy'
-
-unless File.exist? "#{app_root}/bin/rails"
-  system "bin/rake", app_root or begin # rubocop:disable Style/AndOr
-    warn "Automatic creation of the dummy app failed"
-    exit 1
-  end
+if %w[g generate].include? ARGV.first
+  exec "#{__dir__}/rails-engine", *ARGV
+else
+  exec "#{__dir__}/rails-sandbox", *ARGV
 end
-
-Dir.chdir app_root
-exec 'bin/rails', *ARGV
diff --git a/bin/rails-engine b/bin/rails-engine
new file mode 100755
index 0000000..8ff0cae
--- /dev/null
+++ b/bin/rails-engine
@@ -0,0 +1,13 @@
+#!/usr/bin/env ruby
+# This command will automatically be run when you run "rails" with Rails gems
+# installed from the root of your application.
+
+ENGINE_ROOT = File.expand_path('..', __dir__)
+ENGINE_PATH = File.expand_path('../lib/solidus_print_invoice/engine', __dir__)
+
+# Set up gems listed in the Gemfile.
+ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../Gemfile', __dir__)
+require 'bundler/setup' if File.exist?(ENV['BUNDLE_GEMFILE'])
+
+require 'rails/all'
+require 'rails/engine/commands'
diff --git a/bin/rails-sandbox b/bin/rails-sandbox
new file mode 100755
index 0000000..ad2df04
--- /dev/null
+++ b/bin/rails-sandbox
@@ -0,0 +1,16 @@
+#!/usr/bin/env ruby
+
+app_root = 'sandbox'
+
+unless File.exist? "#{app_root}/bin/rails"
+  warn 'Creating the sandbox app...'
+  Dir.chdir "#{__dir__}/.." do
+    system "#{__dir__}/sandbox" or begin
+      warn 'Automatic creation of the sandbox app failed'
+      exit 1
+    end
+  end
+end
+
+Dir.chdir app_root
+exec 'bin/rails', *ARGV
diff --git a/bin/rake b/bin/rake
new file mode 100755
index 0000000..836ad3b
--- /dev/null
+++ b/bin/rake
@@ -0,0 +1,7 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require 'rubygems'
+require 'bundler/setup'
+
+load Gem.bin_path('rake', 'rake')
diff --git a/bin/sandbox b/bin/sandbox
new file mode 100755
index 0000000..00ea309
--- /dev/null
+++ b/bin/sandbox
@@ -0,0 +1,78 @@
+#!/usr/bin/env bash
+
+set -e
+test -z "${DEBUG+empty_string}" || set -x
+
+test "$DB" = "sqlite" && export DB="sqlite3"
+
+if [ -z "$SOLIDUS_BRANCH" ]
+then
+  echo "~~> Use 'export SOLIDUS_BRANCH=[main|v3.2|...]' to control the Solidus branch"
+  SOLIDUS_BRANCH="main"
+fi
+echo "~~> Using branch $SOLIDUS_BRANCH of solidus"
+
+if [ -z "$SOLIDUS_FRONTEND" ]
+then
+  echo "~~> Use 'export SOLIDUS_FRONTEND=[solidus_frontend|solidus_starter_frontend]' to control the Solidus frontend"
+  SOLIDUS_FRONTEND="solidus_frontend"
+fi
+echo "~~> Using branch $SOLIDUS_FRONTEND as the solidus frontend"
+
+extension_name="solidus_print_invoice"
+
+# Stay away from the bundler env of the containing extension.
+function unbundled {
+  ruby -rbundler -e'b = proc {system *ARGV}; Bundler.respond_to?(:with_unbundled_env) ? Bundler.with_unbundled_env(&b) : Bundler.with_clean_env(&b)' -- $@
+}
+
+rm -rf ./sandbox
+unbundled bundle exec rails new sandbox \
+  --database="${DB:-sqlite3}" \
+  --skip-bundle \
+  --skip-git \
+  --skip-keeps \
+  --skip-rc \
+  --skip-spring \
+  --skip-test \
+  --skip-javascript
+
+if [ ! -d "sandbox" ]; then
+  echo 'sandbox rails application failed'
+  exit 1
+fi
+
+cd ./sandbox
+cat <<RUBY >> Gemfile
+gem 'solidus', github: 'solidusio/solidus', branch: '$SOLIDUS_BRANCH'
+gem 'rails-i18n'
+gem 'solidus_i18n'
+
+gem '$extension_name', path: '..'
+
+group :test, :development do
+  platforms :mri do
+    gem 'pry-byebug'
+  end
+end
+RUBY
+
+unbundled bundle install --gemfile Gemfile
+
+unbundled bundle exec rake db:drop db:create
+
+unbundled bundle exec rails generate solidus:install \
+  --auto-accept \
+  --user_class=Spree::User \
+  --enforce_available_locales=true \
+  --with-authentication=true \
+  --payment-method=none \
+  --frontend=${SOLIDUS_FRONTEND} \
+  $@
+
+unbundled bundle exec rails generate solidus:auth:install --auto-run-migrations
+unbundled bundle exec rails generate ${extension_name}:install --auto-run-migrations
+
+echo
+echo "🚀 Sandbox app successfully created for $extension_name!"
+echo "🧪 This app is intended for test purposes."
diff --git a/bin/setup b/bin/setup
index 40d7811..67d9193 100755
--- a/bin/setup
+++ b/bin/setup
@@ -5,4 +5,4 @@ set -vx
 
 gem install bundler --conservative
 bundle update
-bundle exec rake clobber
+bin/rake clobber
diff --git a/lib/generators/solidus_print_invoice/install/install_generator.rb b/lib/generators/solidus_print_invoice/install/install_generator.rb
index 40746dc..3b5a2ad 100644
--- a/lib/generators/solidus_print_invoice/install/install_generator.rb
+++ b/lib/generators/solidus_print_invoice/install/install_generator.rb
@@ -6,15 +6,15 @@ class InstallGenerator < Rails::Generators::Base
       class_option :auto_run_migrations, type: :boolean, default: false
 
       def add_migrations
-        run 'bundle exec rake railties:install:migrations FROM=solidus_print_invoice'
+        run 'bin/rails railties:install:migrations FROM=solidus_print_invoice'
       end
 
       def run_migrations
-        run_migrations = options[:auto_run_migrations] || ['', 'y', 'Y'].include?(ask('Would you like to run the migrations now? [Y/n]'))
+        run_migrations = options[:auto_run_migrations] || ['', 'y', 'Y'].include?(ask('Would you like to run the migrations now? [Y/n]')) # rubocop:disable Layout/LineLength
         if run_migrations
-          run 'bundle exec rake db:migrate'
+          run 'bin/rails db:migrate'
         else
-          puts 'Skipping rake db:migrate, don\'t forget to run it!' # rubocop:disable Rails/Output
+          puts 'Skipping bin/rails db:migrate, don\'t forget to run it!' # rubocop:disable Rails/Output
         end
       end
     end
diff --git a/lib/solidus_print_invoice.rb b/lib/solidus_print_invoice.rb
index 3534ac3..1ba86a6 100755
--- a/lib/solidus_print_invoice.rb
+++ b/lib/solidus_print_invoice.rb
@@ -1,8 +1,5 @@
 # frozen_string_literal: true
 
-require 'solidus_core'
-require 'solidus_support'
-
 require 'solidus_print_invoice/version'
 require 'solidus_print_invoice/engine'
 
diff --git a/lib/solidus_print_invoice/engine.rb b/lib/solidus_print_invoice/engine.rb
index 853756a..8178661 100644
--- a/lib/solidus_print_invoice/engine.rb
+++ b/lib/solidus_print_invoice/engine.rb
@@ -1,7 +1,8 @@
 # frozen_string_literal: true
 
-require 'spree/core'
-require 'deface'
+require 'solidus_core'
+require 'solidus_support'
+
 require_relative '../../app/models/spree/print_invoice_configuration'
 
 module SolidusPrintInvoice
@@ -17,11 +18,11 @@ class Engine < Rails::Engine
       g.test_framework :rspec
     end
 
-    initializer "spree.print_invoice.environment", before: :load_config_initializers do |_app|
+    initializer 'spree.print_invoice.environment', before: :load_config_initializers do |_app|
       Spree::PrintInvoice::Config = Spree::PrintInvoiceConfiguration.new
     end
 
-    initializer "spree.print_invoice.mimetypes" do |_app|
+    initializer 'spree.print_invoice.mimetypes' do |_app|
       Mime::Type.register('application/pdf', :pdf) unless Mime::Type.lookup_by_extension(:pdf)
     end
   end
diff --git a/lib/solidus_print_invoice/factories.rb b/lib/solidus_print_invoice/testing_support/factories.rb
similarity index 100%
rename from lib/solidus_print_invoice/factories.rb
rename to lib/solidus_print_invoice/testing_support/factories.rb
diff --git a/solidus_print_invoice.gemspec b/solidus_print_invoice.gemspec
index d931fe2..0cccbae 100755
--- a/solidus_print_invoice.gemspec
+++ b/solidus_print_invoice.gemspec
@@ -23,21 +23,22 @@ Gem::Specification.new do |s|
   end
 
   s.platform = Gem::Platform::RUBY
-  s.required_ruby_version = '>= 2.4'
+  s.required_ruby_version = '>= 2.5'
+
+  # Specify which files should be added to the gem when it is released.
+  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  files = Dir.chdir(__dir__) { `git ls-files -z`.split("\x0") }
+
+  s.files = files.grep_v(%r{^(test|spec|features)/})
+  s.test_files = files.grep(%r{^(test|spec|features)/})
+  s.bindir = 'exe'
+  s.executables = files.grep(%r{^exe/}) { |f| File.basename(f) }
+  s.require_paths = ['lib']
 
-  s.files = Dir.chdir(File.expand_path(__dir__)) do
-    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
-  end
-  s.test_files = Dir['spec/**/*']
-  s.bindir = "exe"
-  s.executables = s.files.grep(%r{^exe/}) { |f| File.basename(f) }
-  s.require_paths = ["lib"]
-
-  s.add_dependency 'solidus_core', ['>= 2.0.0', '< 4']
-  s.add_dependency 'solidus_support', '~> 0.9'
-  s.add_dependency 'deface'
   s.add_dependency 'prawn', '1.0.0'
-  s.add_dependency 'solidus', ['>= 1.0', '< 4']
+  s.add_dependency 'solidus_core', ['>= 2.0.0', '< 5']
+  s.add_dependency 'solidus_support', '~> 0.8'
 
-  s.add_development_dependency 'solidus_dev_support'
+  s.add_development_dependency 'rails-controller-testing'
+  s.add_development_dependency 'solidus_dev_support', '~> 2.7'
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 73e9fb7..1206779 100755
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -3,22 +3,33 @@
 # Configure Rails Environment
 ENV['RAILS_ENV'] = 'test'
 
+require 'rails-controller-testing'
+Rails::Controller::Testing.install
+
 # Run Coverage report
 require 'solidus_dev_support/rspec/coverage'
 
-require File.expand_path('dummy/config/environment.rb', __dir__)
+# Create the dummy app if it's still missing.
+dummy_env = "#{__dir__}/dummy/config/environment.rb"
+system 'bin/rake extension:test_app' unless File.exist? dummy_env
+require dummy_env
 
 # Requires factories and other useful helpers defined in spree_core.
 require 'solidus_dev_support/rspec/feature_helper'
 
 # Requires supporting ruby files with custom matchers and macros, etc,
 # in spec/support/ and its subdirectories.
-Dir[File.join(File.dirname(__FILE__), 'support/**/*.rb')].each { |f| require f }
+Dir["#{__dir__}/support/**/*.rb"].sort.each { |f| require f }
 
-# Requires factories defined in lib/solidus_print_invoice/factories.rb
-require 'solidus_print_invoice/factories'
+# Requires factories defined in Solidus core and this extension.
+# See: lib/solidus_print_invoice/testing_support/factories.rb
+SolidusDevSupport::TestingSupport::Factories.load_for(SolidusPrintInvoice::Engine)
 
 RSpec.configure do |config|
   config.infer_spec_type_from_file_location!
   config.use_transactional_fixtures = false
+
+  if Spree.solidus_gem_version < Gem::Version.new('2.11')
+    config.extend Spree::TestingSupport::AuthorizationHelpers::Request, type: :system
+  end
 end