Rails 6 (#1403)

* Avoid private `ActiveModel::Dirty#attributes_changed_by_setter`

This method is removed in ActiveModel 6.0, and is private anyway. Avoid calling
it for upgradability.

* Drop support for Rails 5.1

Rails 5.1 support is ended. ActiveFedora 14 will drop support.

* Rely on `ActiveModel::Dirty` to track previous changes

We used to manually set `ActiveModel::Dirty` internals to track "previous
changes". In Rails 6, these internals are completely rewritten and much more
efficient. We can rely on the provided implementation instead of rolling our
own.

* Add support for Rails 6

Rails 6 is here. 🎉

* Drop support for Ruby 2.4

.circleci/config.yml

@@ -46,18 +46,10 @@ workflows:
           ruby_version: 2.5.5
           rails_version: 5.2.3
       - bundle_lint_test:
-          name: ruby2-4_rails5-2
-          ruby_version: 2.4.6
-          rails_version: 5.2.3
-      - bundle_lint_test:
-          name: ruby2-6_rails5-1
+          name: ruby2-6_rails6-0
           ruby_version: 2.6.3
-          rails_version: 5.1.7
+          rails_version: 6.0.0
       - bundle_lint_test:
-          name: ruby2-5_rails5.1
+          name: ruby2-5_rails6.0
           ruby_version: 2.5.5
-          rails_version: 5.1.7
-      - bundle_lint_test:
-          name: ruby2-4_rails5-1
-          ruby_version: 2.4.6
-          rails_version: 5.1.7
+          rails_version: 6.0.0

active-fedora.gemspec

@@ -12,11 +12,11 @@ Gem::Specification.new do |s|
   s.summary     = %q{A convenience libary for manipulating documents in the Fedora Repository.}
   s.description = %q{ActiveFedora provides for creating and managing objects in the Fedora Repository Architecture.}
   s.license = "Apache-2.0"
-  s.required_ruby_version = '~> 2.0'
+  s.required_ruby_version = '~> 2.5'
 
   s.add_dependency 'rsolr', '>= 1.1.2', '< 3'
-  s.add_dependency "activesupport", '>= 4.2.4', '< 5.3'
-  s.add_dependency "activemodel", '>= 4.2.10', '< 5.3'
+  s.add_dependency "activesupport", '>= 5.2'
+  s.add_dependency "activemodel", '>= 5.2'
   s.add_dependency "active-triples", '>= 0.11.0', '< 2.0.0'
   s.add_dependency "deprecation"
   s.add_dependency "ldp", '>= 0.7.0', '< 2'

lib/active_fedora/aggregation/list_source.rb

@@ -12,12 +12,6 @@ def save(*args)
         super
       end
 
-      # Overriding so that we don't track previously_changed, which was
-      # rather expensive.
-      def clear_changed_attributes
-        clear_changes_information
-      end
-
       def changed?
         super || ordered_self.changed?
       end

lib/active_fedora/attributes.rb

@@ -9,11 +9,7 @@ module Attributes
       include Serializers
       include PrimaryKey
 
-      after_save :clear_changed_attributes
-      def clear_changed_attributes
-        @previously_changed = changes
-        clear_attribute_changes(changes.keys)
-      end
+      after_save :changes_applied
     end
 
     def attribute_names

lib/active_fedora/file.rb

@@ -97,11 +97,6 @@ def datastream_will_change!
       attribute_will_change! :ldp_source
     end
 
-    def attribute_will_change!(attr)
-      return super unless attr == 'content'
-      attributes_changed_by_setter[:content] = true
-    end
-
     def remote_content
       return if new_record?
       @ds_content ||= retrieve_content

lib/active_fedora/with_metadata/metadata_node.rb

@@ -15,7 +15,7 @@ def initialize(file)
         @file = file
         super(file.uri, ldp_source.graph)
         return unless self.class.type && !type.include?(self.class.type)
-        attributes_changed_by_setter[:type] = true if type.present?
+        attribute_will_change!(:type) if type.present?
         # Workaround for https://github.com/ActiveTriples/ActiveTriples/issues/123
         get_values(:type) << self.class.type
       end

spec/unit/with_metadata/metadata_node_spec.rb

@@ -19,7 +19,7 @@
         generated_schema.configure type: book
       end
 
-      it { is_expected.to eq('type' => true) }
+      it { is_expected.to match('type' => be_truthy) }
     end
   end