Drop support for rails 4.0 and 4.1

EoL for both was 2016-06-30
http://weblog.rubyonrails.org/2016/6/30/Rails-5-0-final/

PT continued to support them for 15 months after EoL.

.travis.yml

@@ -24,7 +24,6 @@ before_script:
   - sh -c "if [ \"$DB\" = 'postgres' ]; then psql -c 'create database paper_trail_foo;'  -U postgres; fi"
 
 gemfile:
-  - gemfiles/ar_4.0.gemfile
   - gemfiles/ar_4.2.gemfile
   - gemfiles/ar_5.0.gemfile
   - gemfiles/ar_5.1.gemfile

Appraisals

@@ -7,20 +7,16 @@
 # > the version from the appraisal takes precedence.
 # > https://github.com/thoughtbot/appraisal
 
-appraise "ar-4.0" do
-  gem "activerecord", "~> 4.0"
-end
-
 appraise "ar-4.2" do
-  gem "activerecord", "~> 4.2"
+  gem "activerecord", "~> 4.2.9"
 end
 
 appraise "ar-5.0" do
-  gem "activerecord", "~> 5.0.3"
+  gem "activerecord", "~> 5.0.6"
   gem "rails-controller-testing"
 end
 
 appraise "ar-5.1" do
-  gem "rails", "5.1.1"
+  gem "activerecord", "~> 5.1.4"
   gem "rails-controller-testing"
 end

CHANGELOG.md

@@ -7,7 +7,9 @@ recommendations of [keepachangelog.com](http://keepachangelog.com/).
 
 ### Breaking Changes
 
-- Drop support for ruby 2.1, whose EoL was 2017-04-01
+- Drop support for rails 4.0 and 4.1, whose EoL was
+  [2016-06-30](http://weblog.rubyonrails.org/2016/6/30/Rails-5-0-final/)
+- Drop support for ruby 2.1, whose EoL was [2017-04-01](http://bit.ly/2ppWDYa)
 - [#803](https://github.com/airblade/paper_trail/issues/803) -
   where_object_changes no longer supports reading json from a text column
 

gemfiles/ar_4.0.gemfile

@@ -1,7 +0,0 @@
-# This file was generated by Appraisal
-
-source "https://rubygems.org"
-
-gem "activerecord", "~> 4.0"
-
-gemspec path: "../"

gemfiles/ar_master.gemfile

@@ -1,9 +0,0 @@
-# This file was generated by Appraisal
-
-source "https://rubygems.org"
-
-gem "rails", github: "rails/rails"
-gem "rspec-rails", "~> 3.5.1"
-gem "rails-controller-testing"
-
-gemspec path: "../"

lib/paper_trail/record_trail.rb

@@ -1,10 +1,7 @@
 module PaperTrail
   # Represents the "paper trail" for a single record.
   class RecordTrail
-    # The respond_to? check here is specific to ActiveRecord 4.0 and can be
-    # removed when support for ActiveRecord < 4.2 is dropped.
-    RAILS_GTE_5_1 = ::ActiveRecord.respond_to?(:gem_version) &&
-      ::ActiveRecord.gem_version >= ::Gem::Version.new("5.1.0.beta1")
+    RAILS_GTE_5_1 = ::ActiveRecord.gem_version >= ::Gem::Version.new("5.1.0.beta1")
 
     def initialize(record)
       @record = record
@@ -477,9 +474,7 @@ module PaperTrail
       if @in_after_callback && RAILS_GTE_5_1
         @record.attribute_before_last_save(attr_name.to_s)
       else
-        # TODO: after dropping support for rails 4.0, remove send, because
-        # attribute_was is no longer private.
-        @record.send(:attribute_was, attr_name.to_s)
+        @record.attribute_was(attr_name.to_s)
       end
     end
 

lib/paper_trail/version_concern.rb

@@ -12,10 +12,7 @@ module PaperTrail
     extend ::ActiveSupport::Concern
 
     included do
-      # The respond_to? check here is specific to ActiveRecord 4.0 and can be
-      # removed when support for ActiveRecord < 4.2 is dropped.
-      if ::ActiveRecord.respond_to?(:gem_version) &&
-          ::ActiveRecord.gem_version >= Gem::Version.new("5.0")
+      if ::ActiveRecord.gem_version >= Gem::Version.new("5.0")
         belongs_to :item, polymorphic: true, optional: true
       else
         belongs_to :item, polymorphic: true

paper_trail.gemspec

@@ -26,7 +26,7 @@ has been destroyed.
   s.required_ruby_version = ">= 2.2.0"
 
   # Rails does not follow semver, makes breaking changes in minor versions.
-  s.add_dependency "activerecord", [">= 4.0", "< 5.2"]
+  s.add_dependency "activerecord", [">= 4.2", "< 5.2"]
   s.add_dependency "request_store", "~> 1.1"
 
   s.add_development_dependency "appraisal", "~> 2.1"
@@ -34,7 +34,7 @@ has been destroyed.
   s.add_development_dependency "ffaker", "~> 2.5"
 
   # Why `railties`? Possibly used by `spec/dummy_app` boot up?
-  s.add_development_dependency "railties", [">= 4.0", "< 5.2"]
+  s.add_development_dependency "railties", [">= 4.2", "< 5.2"]
 
   s.add_development_dependency "rack-test", "~> 0.6.3"
   s.add_development_dependency "rspec-rails", "~> 3.5"

spec/dummy_app/config/boot.rb

@@ -1,16 +1,8 @@
 require "rubygems"
 
-# We normally use the root project Gemfile (and gemspec), but when we run rake
-# locally (not on travis) in this dummy app, we set the BUNDLE_GEMFILE env.
-# variable. The project Gemfile/gemspec allows AR 4.0, which is a problem
-# because this dummy app uses `enum` in some of its models, and `enum` was
-# introduced in AR 4.1. So, when we run rake here, we use:
-#
-#     BUNDLE_GEMFILE=../../gemfiles/ar_4.2.gemfile bundle exec rake
-#
-# Once we drop support for AR 4.0 and 4.1 this will be less of a problem, but
-# we should keep the ability to specify BUNDLE_GEMFILE because the same
-# situation could come up in the future.
+# When you run rake locally (not on travis) in this dummy app, set the
+# BUNDLE_GEMFILE env. variable to ensure that the correct version of AR is used
+# for e.g. migrations. See examples in CONTRIBUTING.md.
 unless ENV.key?("BUNDLE_GEMFILE")
   gemfile = File.expand_path("../../../../Gemfile", __FILE__)
   if File.exist?(gemfile)