diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 00000000..f43f9d9a
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,77 @@
+AllCops:
+  NewCops: enable
+  SuggestExtensions: false
+  TargetRubyVersion: 3.3
+
+Gemspec/DevelopmentDependencies:
+  Enabled: false
+Layout/HashAlignment:
+  Enabled: false
+Layout/LineLength:
+  Enabled: false
+Layout/SpaceInsideHashLiteralBraces:
+  EnforcedStyle: no_space
+Layout/SpaceAroundOperators:
+    EnforcedStyleForExponentOperator: space
+
+Metrics/AbcSize:
+  Enabled: false
+Metrics/BlockLength:
+  Enabled: false
+Metrics/ClassLength:
+  Enabled: false
+Metrics/CyclomaticComplexity:
+  Enabled: false
+Metrics/MethodLength:
+  Enabled: false
+Metrics/ModuleLength:
+  Enabled: false
+Metrics/PerceivedComplexity:
+  Enabled: false
+
+Naming/PredicateName:
+  Enabled: false
+Naming/VariableNumber:
+  Enabled: false
+
+Style/Documentation:
+  Enabled: false
+Style/ExpandPathArguments:
+  Enabled: false
+Style/GuardClause:
+  Enabled: false
+Style/HashSyntax:
+  Enabled: false
+Style/IfUnlessModifier:
+  Enabled: false
+Style/Lambda:
+  Enabled: false
+Style/MultilineIfModifier:
+  Enabled: false
+Style/NegatedIf:
+  Enabled: false
+Style/Next:
+  Enabled: false
+Style/NumericPredicate:
+  Enabled: false
+Style/ParallelAssignment:
+  Enabled: false
+Style/PercentLiteralDelimiters:
+  Enabled: false
+Style/StringLiterals:
+  Enabled: false
+Style/StringLiteralsInInterpolation:
+  Enabled: false
+Style/SymbolArray:
+  Enabled: false
+
+# specs
+
+Layout/ExtraSpacing:
+  Exclude: [ "test/**/*" ]
+Style/TrailingUnderscoreVariable:
+  Exclude: [ "test/**/*" ]
+Layout/SpaceBeforeFirstArg:
+  Exclude: [ "test/**/*" ]
+Layout/SpaceAroundOperators:
+  Exclude: [ "test/**/*" ]
diff --git a/Appraisals b/Appraisals
index 2883b0b9..d6a967cc 100644
--- a/Appraisals
+++ b/Appraisals
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # on a mac using:
 # bundle config --global build.mysql2 "--with-mysql-dir=$(brew --prefix mysql)"
 
diff --git a/Gemfile b/Gemfile
index aa081768..d68c3d03 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
 
 gemspec
diff --git a/Rakefile b/Rakefile
index 72610ff3..acbde054 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'bundler/setup'
 require 'bundler/gem_tasks'
 require 'rake/testtask'
diff --git a/ancestry.gemspec b/ancestry.gemspec
index 3345d8ed..388a2e03 100644
--- a/ancestry.gemspec
+++ b/ancestry.gemspec
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 lib = File.expand_path('../lib/', __FILE__)
-$:.unshift lib unless $:.include?(lib)
+$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 require 'ancestry/version'
 
 Gem::Specification.new do |s|
@@ -22,6 +24,7 @@ EOF
     "changelog_uri" => "https://github.com/stefankroes/ancestry/blob/master/CHANGELOG.md",
     "source_code_uri" => "https://github.com/stefankroes/ancestry/",
     "bug_tracker_uri" => "https://github.com/stefankroes/ancestry/issues",
+    "rubygems_mfa_required" => "true"
   }
   s.version = Ancestry::VERSION
 
@@ -30,19 +33,19 @@ EOF
   s.homepage = 'https://github.com/stefankroes/ancestry'
   s.license  = 'MIT'
 
-  s.files = Dir[ 
+  s.files = Dir[
     "{lib}/**/*",
     'CHANGELOG.md',
     'MIT-LICENSE',
     'README.md'
   ]
   s.require_paths = ["lib"]
-  
-  s.required_ruby_version     = '>= 2.5'
+
+  s.required_ruby_version = '>= 2.5'
   s.add_runtime_dependency 'activerecord', '>= 5.2.6'
   s.add_development_dependency 'appraisal'
   s.add_development_dependency 'minitest'
-  s.add_development_dependency 'rake',      '~> 13.0'
+  s.add_development_dependency 'rake', '~> 13.0'
   s.add_development_dependency 'simplecov'
   s.add_development_dependency 'yard'
 end
diff --git a/gemfiles/gemfile_52.gemfile b/gemfiles/gemfile_52.gemfile
index eb715511..2d658258 100644
--- a/gemfiles/gemfile_52.gemfile
+++ b/gemfiles/gemfile_52.gemfile
@@ -1,4 +1,5 @@
 # This file was generated by Appraisal
+# frozen_string_literal: true
 
 source "https://rubygems.org"
 
diff --git a/gemfiles/gemfile_60.gemfile b/gemfiles/gemfile_60.gemfile
index f0d662f0..b2e11095 100644
--- a/gemfiles/gemfile_60.gemfile
+++ b/gemfiles/gemfile_60.gemfile
@@ -1,4 +1,5 @@
 # This file was generated by Appraisal
+# frozen_string_literal: true
 
 source "https://rubygems.org"
 
diff --git a/gemfiles/gemfile_61.gemfile b/gemfiles/gemfile_61.gemfile
index 6a2913a1..539c700c 100644
--- a/gemfiles/gemfile_61.gemfile
+++ b/gemfiles/gemfile_61.gemfile
@@ -1,4 +1,5 @@
 # This file was generated by Appraisal
+# frozen_string_literal: true
 
 source "https://rubygems.org"
 
diff --git a/gemfiles/gemfile_70.gemfile b/gemfiles/gemfile_70.gemfile
index a938375d..89796880 100644
--- a/gemfiles/gemfile_70.gemfile
+++ b/gemfiles/gemfile_70.gemfile
@@ -1,4 +1,5 @@
 # This file was generated by Appraisal
+# frozen_string_literal: true
 
 source "https://rubygems.org"
 
diff --git a/gemfiles/gemfile_71.gemfile b/gemfiles/gemfile_71.gemfile
index b077766d..32caf094 100644
--- a/gemfiles/gemfile_71.gemfile
+++ b/gemfiles/gemfile_71.gemfile
@@ -1,4 +1,5 @@
 # This file was generated by Appraisal
+# frozen_string_literal: true
 
 source "https://rubygems.org"
 
diff --git a/gemfiles/gemfile_72.gemfile b/gemfiles/gemfile_72.gemfile
index 60890b37..c9d589eb 100644
--- a/gemfiles/gemfile_72.gemfile
+++ b/gemfiles/gemfile_72.gemfile
@@ -1,4 +1,5 @@
 # This file was generated by Appraisal
+# frozen_string_literal: true
 
 source "https://rubygems.org"
 
diff --git a/lib/ancestry.rb b/lib/ancestry.rb
index e5cd2c61..e9110c16 100644
--- a/lib/ancestry.rb
+++ b/lib/ancestry.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative 'ancestry/version'
 require_relative 'ancestry/class_methods'
 require_relative 'ancestry/instance_methods'
@@ -8,7 +10,7 @@
 require_relative 'ancestry/materialized_path_pg'
 
 I18n.load_path += Dir[File.join(File.expand_path(File.dirname(__FILE__)),
-                                 'ancestry', 'locales', '*.{rb,yml}').to_s]
+                                'ancestry', 'locales', '*.{rb,yml}').to_s]
 
 module Ancestry
   @@default_update_strategy = :ruby
diff --git a/lib/ancestry/class_methods.rb b/lib/ancestry/class_methods.rb
index 4042d587..c924063e 100644
--- a/lib/ancestry/class_methods.rb
+++ b/lib/ancestry/class_methods.rb
@@ -1,7 +1,9 @@
+# frozen_string_literal: true
+
 module Ancestry
   module ClassMethods
     # Fetch tree node if necessary
-    def to_node object
+    def to_node(object)
       if object.is_a?(ancestry_base_class)
         object
       else
@@ -10,13 +12,13 @@ def to_node object
     end
 
     # Scope on relative depth options
-    def scope_depth depth_options, depth
+    def scope_depth(depth_options, depth)
       depth_options.inject(ancestry_base_class) do |scope, option|
         scope_name, relative_depth = option
         if [:before_depth, :to_depth, :at_depth, :from_depth, :after_depth].include? scope_name
           scope.send scope_name, depth + relative_depth
         else
-          raise Ancestry::AncestryException.new(I18n.t("ancestry.unknown_depth_option", scope_name: scope_name))
+          raise Ancestry::AncestryException, I18n.t("ancestry.unknown_depth_option", scope_name: scope_name)
         end
       end
     end
@@ -27,11 +29,11 @@ def scope_depth depth_options, depth
     # To order your hashes pass the order to the arrange method instead of to the scope
 
     # Get all nodes and sort them into an empty hash
-    def arrange options = {}
+    def arrange(options = {})
       if (order = options.delete(:order))
-        arrange_nodes ancestry_base_class.order(order).where(options)
+        arrange_nodes(ancestry_base_class.order(order).where(options))
       else
-        arrange_nodes ancestry_base_class.where(options)
+        arrange_nodes(ancestry_base_class.where(options))
       end
     end
 
@@ -63,10 +65,10 @@ def flatten_arranged_nodes(arranged, nodes = [])
       nodes
     end
 
-     # Arrangement to nested array for serialization
-     # You can also supply your own serialization logic using blocks
-     # also allows you to pass the order just as you can pass it to the arrange method
-    def arrange_serializable options={}, nodes=nil, &block
+    # Arrangement to nested array for serialization
+    # You can also supply your own serialization logic using blocks
+    # also allows you to pass the order just as you can pass it to the arrange method
+    def arrange_serializable(options = {}, nodes = nil, &block)
       nodes = arrange(options) if nodes.nil?
       nodes.map do |parent, children|
         if block_given?
@@ -78,13 +80,13 @@ def arrange_serializable options={}, nodes=nil, &block
     end
 
     def tree_view(column, data = nil)
-      data = arrange unless data
+      data ||= arrange
       data.each do |parent, children|
         if parent.depth == 0
           puts parent[column]
         else
           num = parent.depth - 1
-          indent = "   "*num
+          indent = "   " * num
           puts " #{"|" if parent.depth > 1}#{indent}|_ #{parent[column]}"
         end
         tree_view(column, children) if children
@@ -93,7 +95,7 @@ def tree_view(column, data = nil)
 
     # Pseudo-preordered array of nodes.  Children will always follow parents,
     # This is deterministic unless the parents are missing *and* a sort block is specified
-    def sort_by_ancestry(nodes, &block)
+    def sort_by_ancestry(nodes)
       arranged = nodes if nodes.is_a?(Hash)
 
       unless arranged
@@ -113,48 +115,43 @@ def sort_by_ancestry(nodes, &block)
     # compromised tree integrity is unlikely without explicitly setting cyclic parents or invalid ancestry and circumventing validation
     # just in case, raise an AncestryIntegrityException if issues are detected
     # specify :report => :list to return an array of exceptions or :report => :echo to echo any error messages
-    def check_ancestry_integrity! options = {}
+    def check_ancestry_integrity!(options = {})
       parents = {}
       exceptions = [] if options[:report] == :list
 
       unscoped_where do |scope|
         # For each node ...
         scope.find_each do |node|
-          begin
-            # ... check validity of ancestry column
-            if !node.sane_ancestor_ids?
-              raise Ancestry::AncestryIntegrityException.new(I18n.t("ancestry.invalid_ancestry_column",
-                                                                    :node_id => node.id,
-                                                                    :ancestry_column => "#{node.read_attribute node.class.ancestry_column}"
-                                                                    ))
-            end
-            # ... check that all ancestors exist
-            node.ancestor_ids.each do |ancestor_id|
-              unless exists? ancestor_id
-                raise Ancestry::AncestryIntegrityException.new(I18n.t("ancestry.reference_nonexistent_node",
-                                                                      :node_id => node.id,
-                                                                      :ancestor_id => ancestor_id
-                                                                      ))
-              end
-            end
-            # ... check that all node parents are consistent with values observed earlier
-            node.path_ids.zip([nil] + node.path_ids).each do |node_id, parent_id|
-              parents[node_id] = parent_id unless parents.has_key? node_id
-              unless parents[node_id] == parent_id
-                raise Ancestry::AncestryIntegrityException.new(I18n.t("ancestry.conflicting_parent_id",
-                                                                      :node_id => node_id,
-                                                                      :parent_id => parent_id || 'nil',
-                                                                      :expected => parents[node_id] || 'nil'
-                                                                      ))
-              end
+          # ... check validity of ancestry column
+          if !node.sane_ancestor_ids?
+            raise Ancestry::AncestryIntegrityException, I18n.t("ancestry.invalid_ancestry_column",
+                                                               :node_id => node.id,
+                                                               :ancestry_column => node.read_attribute(node.class.ancestry_column))
+          end
+          # ... check that all ancestors exist
+          node.ancestor_ids.each do |ancestor_id|
+            unless exists?(ancestor_id)
+              raise Ancestry::AncestryIntegrityException, I18n.t("ancestry.reference_nonexistent_node",
+                                                                 :node_id => node.id,
+                                                                 :ancestor_id => ancestor_id)
             end
-          rescue Ancestry::AncestryIntegrityException => integrity_exception
-            case options[:report]
-              when :list then exceptions << integrity_exception
-              when :echo then puts integrity_exception
-              else raise integrity_exception
+          end
+          # ... check that all node parents are consistent with values observed earlier
+          node.path_ids.zip([nil] + node.path_ids).each do |node_id, parent_id|
+            parents[node_id] = parent_id unless parents.key?(node_id)
+            unless parents[node_id] == parent_id
+              raise Ancestry::AncestryIntegrityException, I18n.t("ancestry.conflicting_parent_id",
+                                                                 :node_id => node_id,
+                                                                 :parent_id => parent_id || 'nil',
+                                                                 :expected => parents[node_id] || 'nil')
             end
           end
+        rescue Ancestry::AncestryIntegrityException => e
+          case options[:report]
+          when :list then exceptions << e
+          when :echo then puts e
+          else raise e
+          end
         end
       end
       exceptions if options[:report] == :list
@@ -201,7 +198,7 @@ def restore_ancestry_integrity!
     end
 
     # Build ancestry from parent ids for migration purposes
-    def build_ancestry_from_parent_ids! column=:parent_id, parent_id = nil, ancestor_ids = []
+    def build_ancestry_from_parent_ids!(column = :parent_id, parent_id = nil, ancestor_ids = [])
       unscoped_where do |scope|
         scope.where(column => parent_id).find_each do |node|
           node.without_ancestry_callbacks do
@@ -214,7 +211,7 @@ def build_ancestry_from_parent_ids! column=:parent_id, parent_id = nil, ancestor
 
     # Rebuild depth cache if it got corrupted or if depth caching was just turned on
     def rebuild_depth_cache!
-      raise Ancestry::AncestryException.new(I18n.t("ancestry.cannot_rebuild_depth_cache")) unless respond_to? :depth_cache_column
+      raise(Ancestry::AncestryException, I18n.t("ancestry.cannot_rebuild_depth_cache")) unless respond_to?(:depth_cache_column)
 
       ancestry_base_class.transaction do
         unscoped_where do |scope|
@@ -232,7 +229,7 @@ def rebuild_depth_cache_sql!
     end
 
     def rebuild_counter_cache!
-     if %w(mysql mysql2).include?(connection.adapter_name.downcase)
+      if %w(mysql mysql2).include?(connection.adapter_name.downcase)
         connection.execute %{
           UPDATE #{table_name} AS dest
           LEFT JOIN (
diff --git a/lib/ancestry/exceptions.rb b/lib/ancestry/exceptions.rb
index 9088d8e6..e2efd5d3 100644
--- a/lib/ancestry/exceptions.rb
+++ b/lib/ancestry/exceptions.rb
@@ -1,7 +1,9 @@
+# frozen_string_literal: true
+
 module Ancestry
   class AncestryException < RuntimeError
   end
 
   class AncestryIntegrityException < AncestryException
   end
-end
\ No newline at end of file
+end
diff --git a/lib/ancestry/has_ancestry.rb b/lib/ancestry/has_ancestry.rb
index 8806cfce..69e3cab1 100644
--- a/lib/ancestry/has_ancestry.rb
+++ b/lib/ancestry/has_ancestry.rb
@@ -1,32 +1,36 @@
+# frozen_string_literal: true
+
 module Ancestry
   module HasAncestry
-    def has_ancestry options = {}
+    def has_ancestry(options = {})
       # Check options
-      raise Ancestry::AncestryException.new(I18n.t("ancestry.option_must_be_hash")) unless options.is_a? Hash
-      options.each do |key, value|
-        unless [:ancestry_column, :orphan_strategy, :cache_depth, :depth_cache_column, :touch, :counter_cache, :primary_key_format, :update_strategy, :ancestry_format].include? key
-          raise Ancestry::AncestryException.new(I18n.t("ancestry.unknown_option", key: key.inspect, value: value.inspect))
-        end
+      unless options.is_a? Hash
+        raise Ancestry::AncestryException, I18n.t("ancestry.option_must_be_hash")
+      end
+
+      extra_keys = options.keys - [:ancestry_column, :orphan_strategy, :cache_depth, :depth_cache_column, :touch, :counter_cache, :primary_key_format, :update_strategy, :ancestry_format]
+      if (key = extra_keys.first)
+        raise Ancestry::AncestryException, I18n.t("ancestry.unknown_option", key: key.inspect, value: options[key].inspect)
       end
 
       ancestry_format = options[:ancestry_format] || Ancestry.default_ancestry_format
       if ![:materialized_path, :materialized_path2].include?(ancestry_format)
-        raise Ancestry::AncestryException.new(I18n.t("ancestry.unknown_format", value: ancestry_format))
+        raise Ancestry::AncestryException, I18n.t("ancestry.unknown_format", value: ancestry_format)
       end
 
       orphan_strategy = options[:orphan_strategy] || :destroy
 
       # Create ancestry column accessor and set to option or default
-      self.class_variable_set('@@ancestry_column', options[:ancestry_column] || :ancestry)
+      class_variable_set('@@ancestry_column', options[:ancestry_column] || :ancestry)
       cattr_reader :ancestry_column, instance_reader: false
 
       primary_key_format = options[:primary_key_format].presence || Ancestry.default_primary_key_format
 
-      self.class_variable_set('@@ancestry_delimiter', '/')
+      class_variable_set('@@ancestry_delimiter', '/')
       cattr_reader :ancestry_delimiter, instance_reader: false
 
       # Save self as base class (for STI)
-      self.class_variable_set('@@ancestry_base_class', self)
+      class_variable_set('@@ancestry_base_class', self)
       cattr_reader :ancestry_base_class, instance_reader: false
 
       # Touch ancestors after updating
@@ -41,9 +45,9 @@ def has_ancestry options = {}
       extend Ancestry::ClassMethods
       extend Ancestry::HasAncestry.ancestry_format_module(ancestry_format)
 
-      attribute self.ancestry_column, default: self.ancestry_root
+      attribute ancestry_column, default: ancestry_root
 
-      validates self.ancestry_column, ancestry_validation_options(primary_key_format)
+      validates ancestry_column, ancestry_validation_options(primary_key_format)
 
       update_strategy = options[:update_strategy] || Ancestry.default_update_strategy
       include Ancestry::MaterializedPathPg if update_strategy == :sql
@@ -60,7 +64,7 @@ def has_ancestry options = {}
         alias_method :apply_orphan_strategy, orphan_strategy_helper
         before_destroy :apply_orphan_strategy
       elsif orphan_strategy.to_s != "none"
-        raise Ancestry::AncestryException.new(I18n.t("ancestry.invalid_orphan_strategy"))
+        raise Ancestry::AncestryException, I18n.t("ancestry.invalid_orphan_strategy")
       end
 
       # Create ancestry column accessor and set to option or default
@@ -70,7 +74,7 @@ def has_ancestry options = {}
         depth_cache_sql = options[:depth_cache_column]&.to_s || 'ancestry_depth'
       elsif options[:cache_depth]
         # Create accessor for column name and set to option or default
-        self.cattr_accessor :depth_cache_column
+        cattr_accessor :depth_cache_column
         self.depth_cache_column =
           if options[:cache_depth] == true
             options[:depth_cache_column]&.to_s || 'ancestry_depth'
@@ -119,6 +123,7 @@ def has_ancestry options = {}
 
     def acts_as_tree(*args)
       return super if defined?(super)
+
       has_ancestry(*args)
     end
 
diff --git a/lib/ancestry/instance_methods.rb b/lib/ancestry/instance_methods.rb
index 8d898093..7681e9ff 100644
--- a/lib/ancestry/instance_methods.rb
+++ b/lib/ancestry/instance_methods.rb
@@ -1,8 +1,10 @@
+# frozen_string_literal: true
+
 module Ancestry
   module InstanceMethods
     # Validate that the ancestors don't include itself
     def ancestry_exclude_self
-      errors.add(:base, I18n.t("ancestry.exclude_self", class_name: self.class.name.humanize)) if ancestor_ids.include? self.id
+      errors.add(:base, I18n.t("ancestry.exclude_self", class_name: self.class.name.humanize)) if ancestor_ids.include?(id)
     end
 
     # Update descendants with new ancestry (after update)
@@ -49,7 +51,7 @@ def apply_orphan_strategy_adopt
 
       descendants.each do |descendant|
         descendant.without_ancestry_callbacks do
-          descendant.update_attribute :ancestor_ids, (descendant.ancestor_ids.delete_if { |x| x == self.id })
+          descendant.update_attribute :ancestor_ids, (descendant.ancestor_ids.delete_if { |x| x == id })
         end
       end
     end
@@ -58,7 +60,7 @@ def apply_orphan_strategy_adopt
     def apply_orphan_strategy_restrict
       return if ancestry_callbacks_disabled? || new_record?
 
-      raise Ancestry::AncestryException.new(I18n.t("ancestry.cannot_delete_descendants")) unless is_childless?
+      raise(Ancestry::AncestryException, I18n.t("ancestry.cannot_delete_descendants")) unless is_childless?
     end
 
     # Touch each of this record's ancestors (after save)
@@ -93,7 +95,7 @@ def decrease_parent_counter_cache
     def update_parent_counter_cache
       return unless saved_change_to_attribute?(self.class.ancestry_column)
 
-      if parent_id_was = parent_id_before_last_save
+      if (parent_id_was = parent_id_before_last_save)
         self.class.ancestry_base_class.decrement_counter counter_cache_column, parent_id_was
       end
 
@@ -105,13 +107,13 @@ def update_parent_counter_cache
     def has_parent?
       ancestor_ids.present?
     end
-    alias :ancestors? :has_parent?
+    alias ancestors? has_parent?
 
     def ancestry_changed?
       column = self.class.ancestry_column.to_s
-        # These methods return nil if there are no changes.
-        # This was fixed in a refactoring in rails 6.0: https://github.com/rails/rails/pull/35933
-        !!(will_save_change_to_attribute?(column) || saved_change_to_attribute?(column))
+      # These methods return nil if there are no changes.
+      # This was fixed in a refactoring in rails 6.0: https://github.com/rails/rails/pull/35933
+      !!(will_save_change_to_attribute?(column) || saved_change_to_attribute?(column))
     end
 
     def sane_ancestor_ids?
@@ -131,8 +133,9 @@ def sane_ancestor_ids?
       self.validation_context = current_context
     end
 
-    def ancestors depth_options = {}
+    def ancestors(depth_options = {})
       return self.class.ancestry_base_class.none unless has_parent?
+
       self.class.ancestry_base_class.scope_depth(depth_options, depth).ordered_by_ancestry.ancestors_of(self)
     end
 
@@ -148,7 +151,7 @@ def path_ids_in_database
       ancestor_ids_in_database + [id]
     end
 
-    def path depth_options = {}
+    def path(depth_options = {})
       self.class.ancestry_base_class.scope_depth(depth_options, depth).ordered_by_ancestry.inpath_of(self)
     end
 
@@ -161,25 +164,25 @@ def cache_depth
     end
 
     def ancestor_of?(node)
-      node.ancestor_ids.include?(self.id)
+      node.ancestor_ids.include?(id)
     end
 
     # Parent
 
     # currently parent= does not work in after save callbacks
     # assuming that parent hasn't changed
-    def parent= parent
+    def parent=(parent)
       self.ancestor_ids = parent ? parent.path_ids : []
     end
 
-    def parent_id= new_parent_id
+    def parent_id=(new_parent_id)
       self.parent = new_parent_id.present? ? unscoped_find(new_parent_id) : nil
     end
 
     def parent_id
       ancestor_ids.last if has_parent?
     end
-    alias :parent_id? :ancestors?
+    alias parent_id? ancestors?
 
     def parent
       if has_parent?
@@ -190,7 +193,7 @@ def parent
     end
 
     def parent_of?(node)
-      self.id == node.parent_id
+      id == node.parent_id
     end
 
     # Root
@@ -210,10 +213,10 @@ def root
     def is_root?
       !has_parent?
     end
-    alias :root? :is_root?
+    alias root? is_root?
 
     def root_of?(node)
-      self.id == node.root_id
+      id == node.root_id
     end
 
     # Children
@@ -227,7 +230,7 @@ def child_ids
     end
 
     def has_children?
-      self.children.exists?
+      children.exists?
     end
     alias_method :children?, :has_children?
 
@@ -237,7 +240,7 @@ def is_childless?
     alias_method :childless?, :is_childless?
 
     def child_of?(node)
-      self.parent_id == node.id
+      parent_id == node.id
     end
 
     # Siblings
@@ -252,7 +255,7 @@ def sibling_ids
     end
 
     def has_siblings?
-      self.siblings.count > 1
+      siblings.count > 1
     end
     alias_method :siblings?, :has_siblings?
 
@@ -262,16 +265,16 @@ def is_only_child?
     alias_method :only_child?, :is_only_child?
 
     def sibling_of?(node)
-      self.ancestor_ids == node.ancestor_ids
+      ancestor_ids == node.ancestor_ids
     end
 
     # Descendants
 
-    def descendants depth_options = {}
+    def descendants(depth_options = {})
       self.class.ancestry_base_class.ordered_by_ancestry.scope_depth(depth_options, depth).descendants_of(self)
     end
 
-    def descendant_ids depth_options = {}
+    def descendant_ids(depth_options = {})
       descendants(depth_options).pluck(self.class.primary_key)
     end
 
@@ -281,11 +284,11 @@ def descendant_of?(node)
 
     # Indirects
 
-    def indirects depth_options = {}
+    def indirects(depth_options = {})
       self.class.ancestry_base_class.ordered_by_ancestry.scope_depth(depth_options, depth).indirects_of(self)
     end
 
-    def indirect_ids depth_options = {}
+    def indirect_ids(depth_options = {})
       indirects(depth_options).pluck(self.class.primary_key)
     end
 
@@ -295,11 +298,11 @@ def indirect_of?(node)
 
     # Subtree
 
-    def subtree depth_options = {}
+    def subtree(depth_options = {})
       self.class.ancestry_base_class.ordered_by_ancestry.scope_depth(depth_options, depth).subtree_of(self)
     end
 
-    def subtree_ids depth_options = {}
+    def subtree_ids(depth_options = {})
       subtree(depth_options).pluck(self.class.primary_key)
     end
 
@@ -324,33 +327,31 @@ def ancestry_callbacks_disabled?
 
     def unscoped_descendants
       unscoped_where do |scope|
-        scope.where self.class.ancestry_base_class.descendant_conditions(self)
+        scope.where(self.class.ancestry_base_class.descendant_conditions(self))
       end
     end
 
     def unscoped_descendants_before_last_save
       unscoped_where do |scope|
-        scope.where self.class.ancestry_base_class.descendant_before_last_save_conditions(self)
+        scope.where(self.class.ancestry_base_class.descendant_before_last_save_conditions(self))
       end
     end
 
     # works with after save context (hence before_last_save)
     def unscoped_current_and_previous_ancestors
       unscoped_where do |scope|
-        scope.where scope.primary_key => (ancestor_ids + ancestor_ids_before_last_save).uniq
+        scope.where(scope.primary_key => (ancestor_ids + ancestor_ids_before_last_save).uniq)
       end
     end
 
-    def unscoped_find id
+    def unscoped_find(id)
       unscoped_where do |scope|
-        scope.find id
+        scope.find(id)
       end
     end
 
-    def unscoped_where
-      self.class.ancestry_base_class.unscoped_where do |scope|
-        yield scope
-      end
+    def unscoped_where(&block)
+      self.class.ancestry_base_class.unscoped_where(&block)
     end
   end
 end
diff --git a/lib/ancestry/materialized_path.rb b/lib/ancestry/materialized_path.rb
index d53854af..d70a97cb 100644
--- a/lib/ancestry/materialized_path.rb
+++ b/lib/ancestry/materialized_path.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Ancestry
   # store ancestry as grandparent_id/parent_id
   # root a=nil,id=1   children=id,id/%      == 1, 1/%
@@ -114,6 +116,7 @@ def generate_ancestry(ancestor_ids)
 
     def parse_ancestry_column(obj)
       return [] if obj.nil? || obj == ancestry_root
+
       obj_ids = obj.split(ancestry_delimiter).delete_if(&:blank?)
       primary_key_is_an_integer? ? obj_ids.map!(&:to_i) : obj_ids
     end
@@ -132,7 +135,7 @@ def concat(*args)
 
     def self.construct_depth_sql(table_name, ancestry_column, ancestry_delimiter)
       tmp = %{(LENGTH(#{table_name}.#{ancestry_column}) - LENGTH(REPLACE(#{table_name}.#{ancestry_column},'#{ancestry_delimiter}','')))}
-      tmp = tmp + "/#{ancestry_delimiter.size}" if ancestry_delimiter.size > 1
+      tmp += "/#{ancestry_delimiter.size}" if ancestry_delimiter.size > 1
       "(CASE WHEN #{table_name}.#{ancestry_column} IS NULL THEN 0 ELSE 1 + #{tmp} END)"
     end
 
@@ -140,7 +143,7 @@ def self.construct_depth_sql(table_name, ancestry_column, ancestry_delimiter)
 
     def ancestry_validation_options(ancestry_primary_key_format)
       {
-        format: { with: ancestry_format_regexp(ancestry_primary_key_format) },
+        format: {with: ancestry_format_regexp(ancestry_primary_key_format)},
         allow_nil: ancestry_nil_allowed?
       }
     end
@@ -158,7 +161,7 @@ module InstanceMethods
       def ancestors?
         read_attribute(self.class.ancestry_column) != self.class.ancestry_root
       end
-      alias :has_parent? :ancestors?
+      alias has_parent? ancestors?
 
       def ancestor_ids=(value)
         write_attribute(self.class.ancestry_column, self.class.generate_ancestry(value))
@@ -186,7 +189,7 @@ def parent_id_before_last_save
 
       # optimization - better to go directly to column and avoid parsing
       def sibling_of?(node)
-        self.read_attribute(self.class.ancestry_column) == node.read_attribute(node.class.ancestry_column)
+        read_attribute(self.class.ancestry_column) == node.read_attribute(node.class.ancestry_column)
       end
 
       # The ancestry value for this record's children
@@ -195,7 +198,8 @@ def sibling_of?(node)
       # NOTE: This could have been called child_ancestry_in_database
       #       the child records were created from the version in the database
       def child_ancestry
-        raise Ancestry::AncestryException.new(I18n.t("ancestry.no_child_for_new_record")) if new_record?
+        raise(Ancestry::AncestryException, I18n.t("ancestry.no_child_for_new_record")) if new_record?
+
         [attribute_in_database(self.class.ancestry_column), id].compact.join(self.class.ancestry_delimiter)
       end
 
@@ -204,9 +208,10 @@ def child_ancestry
       # to find the old children and bring them along (or to )
       # This is not valid in a new record's after_save.
       def child_ancestry_before_last_save
-        if new_record? || respond_to?(:previously_new_record?) && previously_new_record?
-          raise Ancestry::AncestryException.new(I18n.t("ancestry.no_child_for_new_record"))
+        if new_record? || (respond_to?(:previously_new_record?) && previously_new_record?)
+          raise Ancestry::AncestryException, I18n.t("ancestry.no_child_for_new_record")
         end
+
         [attribute_before_last_save(self.class.ancestry_column), id].compact.join(self.class.ancestry_delimiter)
       end
     end
diff --git a/lib/ancestry/materialized_path2.rb b/lib/ancestry/materialized_path2.rb
index 46887852..df4ef8a2 100644
--- a/lib/ancestry/materialized_path2.rb
+++ b/lib/ancestry/materialized_path2.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Ancestry
   # store ancestry as /grandparent_id/parent_id/
   # root: a=/,id=1    children=#{a}#{id}/% == /1/%
@@ -47,7 +49,7 @@ def generate_ancestry(ancestor_ids)
     # module method
     def self.construct_depth_sql(table_name, ancestry_column, ancestry_delimiter)
       tmp = %{(LENGTH(#{table_name}.#{ancestry_column}) - LENGTH(REPLACE(#{table_name}.#{ancestry_column},'#{ancestry_delimiter}','')))}
-      tmp = tmp + "/#{ancestry_delimiter.size}" if ancestry_delimiter.size > 1
+      tmp += "/#{ancestry_delimiter.size}" if ancestry_delimiter.size > 1
       "(#{tmp} -1)"
     end
 
@@ -64,15 +66,17 @@ def ancestry_format_regexp(primary_key_format)
     module InstanceMethods
       # Please see notes for MaterializedPath#child_ancestry
       def child_ancestry
-        raise Ancestry::AncestryException.new(I18n.t("ancestry.no_child_for_new_record")) if new_record?
+        raise(Ancestry::AncestryException, I18n.t("ancestry.no_child_for_new_record")) if new_record?
+
         "#{attribute_in_database(self.class.ancestry_column)}#{id}#{self.class.ancestry_delimiter}"
       end
 
       # Please see notes for MaterializedPath#child_ancestry_before_last_save
       def child_ancestry_before_last_save
-        if new_record? || respond_to?(:previously_new_record?) && previously_new_record?
-          raise Ancestry::AncestryException.new(I18n.t("ancestry.no_child_for_new_record"))
+        if new_record? || (respond_to?(:previously_new_record?) && previously_new_record?)
+          raise(Ancestry::AncestryException, I18n.t("ancestry.no_child_for_new_record"))
         end
+
         "#{attribute_before_last_save(self.class.ancestry_column)}#{id}#{self.class.ancestry_delimiter}"
       end
     end
diff --git a/lib/ancestry/materialized_path_pg.rb b/lib/ancestry/materialized_path_pg.rb
index 5cb35030..46de2d51 100644
--- a/lib/ancestry/materialized_path_pg.rb
+++ b/lib/ancestry/materialized_path_pg.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Ancestry
   module MaterializedPathPg
     # Update descendants with new ancestry (after update)
@@ -5,8 +7,8 @@ def update_descendants_with_new_ancestry
       # If enabled and node is existing and ancestry was updated and the new ancestry is sane ...
       # The only way the ancestry could be bad is via `update_attribute` with a bad value
       if !ancestry_callbacks_disabled? && sane_ancestor_ids?
-        old_ancestry = self.class.generate_ancestry( path_ids_before_last_save )
-        new_ancestry = self.class.generate_ancestry( path_ids )
+        old_ancestry = self.class.generate_ancestry(path_ids_before_last_save)
+        new_ancestry = self.class.generate_ancestry(path_ids)
         update_clause = {
           self.class.ancestry_column => Arel.sql("regexp_replace(#{self.class.ancestry_column}, '^#{Regexp.escape(old_ancestry)}', '#{new_ancestry}')")
         }
diff --git a/lib/ancestry/version.rb b/lib/ancestry/version.rb
index 08fbe39a..3e757431 100644
--- a/lib/ancestry/version.rb
+++ b/lib/ancestry/version.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Ancestry
   VERSION = '5.0.0'
 end
diff --git a/test/concerns/arrangement_test.rb b/test/concerns/arrangement_test.rb
index 8257334c..bc0b125d 100644
--- a/test/concerns/arrangement_test.rb
+++ b/test/concerns/arrangement_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class ArrangementTest < ActiveSupport::TestCase
@@ -6,7 +8,7 @@ def root_node(model)
   end
 
   def middle_node(model)
-    root_node(model).children.sort_by(&:id).first
+    root_node(model).children.min_by(&:id)
   end
 
   def leaf_node(model)
@@ -23,7 +25,7 @@ def assert_tree(arranged_nodes, size_at_depth)
       assert_equal size_at_depth[1], children.size
       assert_equal node.children.sort_by(&:id), children.keys.sort_by(&:id)
 
-      assert_tree(children, size_at_depth[1..-1])
+      assert_tree(children, size_at_depth[1..])
     end
   end
 
@@ -39,7 +41,7 @@ def assert_tree_path(arranged_nodes, expected_ids)
     arranged_nodes.each do |node, children|
       assert_equal expected_ids[0], node.id
 
-      assert_tree_path(children, expected_ids[1..-1])
+      assert_tree_path(children, expected_ids[1..])
     end
   end
 
@@ -131,20 +133,25 @@ def test_arrange_serializable
     AncestryTestDatabase.with_model :depth => 2, :width => 2 do |model, _roots|
       col = model.ancestry_column
       # materialized path 2 has a slash at the beginning and end
-      fmt = AncestryTestDatabase.materialized_path2? ? -> (a) { a ? "/#{a}/" : "/" } : -> (a) {a}
-      result = [{
-        col=>fmt[nil], "id"=>4, "children"=> [{
-          col=>fmt["4"], "id"=>6, "children" => []
-        }, {
-          col=>fmt["4"], "id"=>5, "children" => []
-        }]
-      }, {
-        col=>fmt[nil], "id"=>1, "children"=> [{
-          col=>fmt["1"], "id"=>3, "children"=>[]
+      fmt =
+        if AncestryTestDatabase.materialized_path2?
+          ->(a) { a ? "/#{a}/" : "/" }
+        else
+          ->(a) { a }
+        end
+      result = [
+        {
+          col => fmt[nil], "id" => 4, "children" => [
+            {col => fmt["4"], "id" => 6, "children" => []},
+            {col => fmt["4"], "id" => 5, "children" => []}
+          ]
         }, {
-          col=>fmt["1"], "id"=>2, "children"=>[]
-        }]
-      }]
+          col => fmt[nil], "id" => 1, "children" => [
+            {col => fmt["1"], "id" => 3, "children" => []},
+            {col => fmt["1"], "id" => 2, "children" => []}
+          ]
+        }
+      ]
 
       assert_equal model.arrange_serializable(order: "id desc"), result
     end
@@ -152,19 +159,19 @@ def test_arrange_serializable
 
   def test_arrange_serializable_with_block
     AncestryTestDatabase.with_model :depth => 2, :width => 2 do |model, _roots|
-      expected_result = [{
-        "id"=>4, "children"=>[{
-          "id"=>6
-        }, {
-          "id"=>5
-        }]
-      }, {
-        "id"=>1, "children"=> [{
-          "id"=>3
+      expected_result = [
+        {
+          "id" => 4, "children" => [
+            {"id" => 6},
+            {"id" => 5}
+          ]
         }, {
-          "id"=>2
-        }]
-      }]
+          "id" => 1, "children" => [
+            {"id" => 3},
+            {"id" => 2}
+          ]
+        }
+      ]
       result = model.arrange_serializable(order: "id desc") do |parent, children|
         out = {}
         out["id"] = parent.id
diff --git a/test/concerns/build_ancestry_test.rb b/test/concerns/build_ancestry_test.rb
index f1d14e81..62879438 100644
--- a/test/concerns/build_ancestry_test.rb
+++ b/test/concerns/build_ancestry_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class BuildAncestryTest < ActiveSupport::TestCase
diff --git a/test/concerns/counter_cache_test.rb b/test/concerns/counter_cache_test.rb
index 2093332c..a32fc34c 100644
--- a/test/concerns/counter_cache_test.rb
+++ b/test/concerns/counter_cache_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class CounterCacheTest < ActiveSupport::TestCase
diff --git a/test/concerns/db_test.rb b/test/concerns/db_test.rb
index fe2001c8..67878bd8 100644
--- a/test/concerns/db_test.rb
+++ b/test/concerns/db_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class DbTest < ActiveSupport::TestCase
diff --git a/test/concerns/default_scopes_test.rb b/test/concerns/default_scopes_test.rb
index 4abfa383..965ed585 100644
--- a/test/concerns/default_scopes_test.rb
+++ b/test/concerns/default_scopes_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class DefaultScopesTest < ActiveSupport::TestCase
diff --git a/test/concerns/depth_caching_test.rb b/test/concerns/depth_caching_test.rb
index 61a9158a..2519450f 100644
--- a/test/concerns/depth_caching_test.rb
+++ b/test/concerns/depth_caching_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class DepthCachingTest < ActiveSupport::TestCase
diff --git a/test/concerns/depth_constraints_test.rb b/test/concerns/depth_constraints_test.rb
index 86912a5c..95a2c6b8 100644
--- a/test/concerns/depth_constraints_test.rb
+++ b/test/concerns/depth_constraints_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class DepthConstraintsTest < ActiveSupport::TestCase
diff --git a/test/concerns/has_ancestry_test.rb b/test/concerns/has_ancestry_test.rb
index 01cc7e7f..3a46d06a 100644
--- a/test/concerns/has_ancestry_test.rb
+++ b/test/concerns/has_ancestry_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class HasAncestryTreeTest < ActiveSupport::TestCase
@@ -96,7 +98,7 @@ def test_setup_test_nodes
   end
 
   def test_primary_key_is_an_integer
-    AncestryTestDatabase.with_model(extra_columns: { string_id: :string }) do |model|
+    AncestryTestDatabase.with_model(extra_columns: {string_id: :string}) do |model|
       model.primary_key = :string_id
 
       assert !model.primary_key_is_an_integer?
diff --git a/test/concerns/hooks_test.rb b/test/concerns/hooks_test.rb
index 465b6068..033f3a12 100644
--- a/test/concerns/hooks_test.rb
+++ b/test/concerns/hooks_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class ArrangementTest < ActiveSupport::TestCase
@@ -7,7 +9,6 @@ def test_has_ancestry_in_after_save
       :orphan_strategy => :adopt,
       :extra_columns => {:name => :string, :name_path => :string}
     ) do |model|
-
       model.class_eval do
         before_save :before_save_hook
 
@@ -33,9 +34,8 @@ def before_save_hook
 
   def test_update_descendants_with_changed_parent_value
     AncestryTestDatabase.with_model(
-      extra_columns: { name: :string, name_path: :string }
+      extra_columns: {name: :string, name_path: :string}
     ) do |model|
-
       model.class_eval do
         before_save :update_name_path
         # this example will only work if the name field is unique across all levels
@@ -76,9 +76,9 @@ def update_descendants_hook(descendants_clause, old_ancestry, new_ancestry)
       assert_equal("changed", m5.reload.name_path)
       assert_equal([m5.id], m2.reload.ancestor_ids)
       assert_equal("changed/child", m2.reload.name_path)
-      assert_equal([m5.id,m2.id], m3.reload.ancestor_ids)
+      assert_equal([m5.id, m2.id], m3.reload.ancestor_ids)
       assert_equal("changed/child/grandchild", m3.reload.name_path)
-      assert_equal([m5.id,m2.id,m3.id], m4.reload.ancestor_ids)
+      assert_equal([m5.id, m2.id, m3.id], m4.reload.ancestor_ids)
       assert_equal("changed/child/grandchild/grandchild's grand", m4.reload.name_path)
     end
   end
@@ -132,15 +132,16 @@ def before_hook
   # see f94b22ba https://github.com/stefankroes/ancestry/pull/263
   def test_node_creation_in_after_commit
     AncestryTestDatabase.with_model do |model|
-      children=[]
+      children = []
       model.instance_eval do
         attr_accessor :idx
-        self.after_commit do
-          children << self.children.create!(:idx => self.idx - 1) if self.idx > 0
+
+        after_commit do
+          children << self.children.create!(:idx => idx - 1) if idx > 0
         end
       end
       model.create!(:idx => 3)
-      assert_equal [1,2,3], children.first.ancestor_ids
+      assert_equal [1, 2, 3], children.first.ancestor_ids
     end
   end
 end
diff --git a/test/concerns/integrity_checking_and_restoration_test.rb b/test/concerns/integrity_checking_and_restoration_test.rb
index 2b8071f9..474a66e4 100644
--- a/test/concerns/integrity_checking_and_restoration_test.rb
+++ b/test/concerns/integrity_checking_and_restoration_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class IntegrityCheckingAndRestaurationTest < ActiveSupport::TestCase
@@ -49,7 +51,7 @@ def test_integrity_checking
     end
   end
 
-  def assert_integrity_restoration model
+  def assert_integrity_restoration(model)
     assert_raise Ancestry::AncestryIntegrityException do
       model.check_ancestry_integrity!
     end
@@ -57,8 +59,8 @@ def assert_integrity_restoration model
     assert_nothing_raised do
       model.check_ancestry_integrity!
     end
-    assert model.all.any? {|node| node.has_parent? }, "Expected some nodes not to be roots"
-    assert_equal model.count, model.roots.collect {|node| node.descendants.count + 1 }.sum
+    assert model.all.any?(&:has_parent?), "Expected some nodes not to be roots"
+    assert_equal model.count, model.roots.collect { |node| node.descendants.count + 1 }.sum
   end
 
   def test_integrity_restoration
diff --git a/test/concerns/materialized_path2_test.rb b/test/concerns/materialized_path2_test.rb
index 83a1ce98..aa566267 100644
--- a/test/concerns/materialized_path2_test.rb
+++ b/test/concerns/materialized_path2_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class MaterializedPath2Test < ActiveSupport::TestCase
diff --git a/test/concerns/materialized_path_test.rb b/test/concerns/materialized_path_test.rb
index 328f7d12..9a2c1a38 100644
--- a/test/concerns/materialized_path_test.rb
+++ b/test/concerns/materialized_path_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class MaterializedPathTest < ActiveSupport::TestCase
@@ -14,23 +16,23 @@ def test_ancestry_column_values
 
       # saved
       node.save!
-      assert_ancestry node, nil, child: "#{node.id}"
+      assert_ancestry node, nil, child: node.id.to_s
 
       # changed
       node.ancestor_ids = [root.id]
-      assert_ancestry node, "#{root.id}", db: nil, child: "#{node.id}"
+      assert_ancestry node, root.id.to_s, db: nil, child: node.id.to_s
 
       # changed saved
       node.save!
-      assert_ancestry node, "#{root.id}", child: "#{root.id}/#{node.id}"
+      assert_ancestry node, root.id.to_s, child: "#{root.id}/#{node.id}"
 
       # reloaded
       node.reload
-      assert_ancestry node, "#{root.id}", child: "#{root.id}/#{node.id}"
+      assert_ancestry node, root.id.to_s, child: "#{root.id}/#{node.id}"
 
       # fresh node
       node = model.find(node.id)
-      assert_ancestry node, "#{root.id}", child: "#{root.id}/#{node.id}"
+      assert_ancestry node, root.id.to_s, child: "#{root.id}/#{node.id}"
     end
   end
 
diff --git a/test/concerns/orphan_strategies_test.rb b/test/concerns/orphan_strategies_test.rb
index 19147681..18d6a260 100644
--- a/test/concerns/orphan_strategies_test.rb
+++ b/test/concerns/orphan_strategies_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class OphanStrategiesTest < ActiveSupport::TestCase
@@ -10,7 +12,7 @@ def test_setting_invalid_orphan_strategy
   end
 
   def test_orphan_rootify_strategy
-    AncestryTestDatabase.with_model orphan_strategy: :rootify, :depth => 3, :width => 3 do |model, roots|
+    AncestryTestDatabase.with_model orphan_strategy: :rootify, :depth => 3, :width => 3 do |_model, roots|
       root = roots.first.first
       children = root.children.to_a
       root.destroy
@@ -48,7 +50,7 @@ def verify_parent_exists
   end
 
   def test_orphan_restrict_strategy
-    AncestryTestDatabase.with_model orphan_strategy: :restrict, :depth => 3, :width => 3 do |model, roots|
+    AncestryTestDatabase.with_model orphan_strategy: :restrict, :depth => 3, :width => 3 do |_model, roots|
       root = roots.first.first
       assert_raise Ancestry::AncestryException do
         root.destroy
@@ -61,11 +63,11 @@ def test_orphan_restrict_strategy
 
   def test_orphan_adopt_strategy
     AncestryTestDatabase.with_model orphan_strategy: :adopt do |model|
-      n1 = model.create!                  #create a root node
-      n2 = model.create!(:parent => n1)   #create child with parent=root
-      n3 = model.create!(:parent => n2)   #create child with parent=n2, depth = 2
-      n4 = model.create!(:parent => n2)   #create child with parent=n2, depth = 2
-      n5 = model.create!(:parent => n4)   #create child with parent=n4, depth = 3
+      n1 = model.create!                  # create a root node
+      n2 = model.create!(:parent => n1)   # create child with parent=root
+      n3 = model.create!(:parent => n2)   # create child with parent=n2, depth = 2
+      n4 = model.create!(:parent => n2)   # create child with parent=n2, depth = 2
+      n5 = model.create!(:parent => n4)   # create child with parent=n4, depth = 3
       n2.destroy                          # delete a node with desecendants
       n3.reload
       n5.reload
@@ -82,7 +84,7 @@ def test_orphan_adopt_strategy
 
   # DEPRECATED - please see test_apply_orphan_strategy_none for pattern instead
   def test_override_apply_orphan_strategy
-    AncestryTestDatabase.with_model orphan_strategy: :destroy do |model, roots|
+    AncestryTestDatabase.with_model orphan_strategy: :destroy do |model, _roots|
       root  = model.create!
       child = model.create!(:parent => root)
       model.class_eval do
@@ -99,7 +101,7 @@ def apply_orphan_strategy
   end
 
   def test_apply_orphan_strategy_none
-    AncestryTestDatabase.with_model orphan_strategy: :none do |model, roots|
+    AncestryTestDatabase.with_model orphan_strategy: :none do |model, _roots|
       root  = model.create!
       child = model.create!(:parent => root)
       model.class_eval do
@@ -125,7 +127,7 @@ def apply_orphan_strategy_abc
         end
       end
 
-      root  = model.create!
+      root = model.create!
       3.times { root.children.create! }
       model.create! # a node that is not affected
       assert_difference 'model.count', -4 do
@@ -145,7 +147,7 @@ def apply_orphan_strategy_abc
 
         has_ancestry orphan_strategy: :abc, ancestry_column: AncestryTestDatabase.ancestry_column
       end
-      root  = model.create!
+      root = model.create!
       3.times { root.children.create! }
       model.create! # a node that is not affected
       assert_difference 'model.count', -4 do
@@ -156,17 +158,17 @@ def apply_orphan_strategy_abc
 
   def test_basic_delete
     AncestryTestDatabase.with_model do |model|
-      n1 = model.create!                  #create a root node
-      n2 = model.create!(:parent => n1)   #create child with parent=root
+      n1 = model.create!                      # create a root node
+      n2 = model.create!(:parent => n1)       # create child with parent=root
       n2.destroy!
-      model.find(n1.id)                   # parent should exist
+      model.find(n1.id)                       # parent should exist
 
-      n1 = model.create!                  #create a root node
-      n2 = model.create!(:parent => n1)   #create child with parent=root
+      n1 = model.create!                      # create a root node
+      n2 = model.create!(:parent => n1)       # create child with parent=root
       n1.destroy!
       assert_nil(model.find_by(:id => n2.id)) # child should not exist
 
-      n1 = model.create!                  #create a root node
+      n1 = model.create!                      # create a root node
       n1.destroy!
     end
   end
diff --git a/test/concerns/relations_test.rb b/test/concerns/relations_test.rb
index 0aa3a8aa..30f3f891 100644
--- a/test/concerns/relations_test.rb
+++ b/test/concerns/relations_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class RelationsTest < ActiveSupport::TestCase
diff --git a/test/concerns/scopes_test.rb b/test/concerns/scopes_test.rb
index 8efb7875..b31b168e 100644
--- a/test/concerns/scopes_test.rb
+++ b/test/concerns/scopes_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 # all class nodes used to look up objects belong here
@@ -64,7 +66,7 @@ def test_order_by_reverse
     AncestryTestDatabase.with_model(:width => 1, :depth => 3) do |model, _roots|
       child = model.last
       assert child
-      assert_nothing_raised do #IrreversibleOrderError
+      assert_nothing_raised do # IrreversibleOrderError
         assert child.ancestors.last
       end
     end
@@ -104,9 +106,9 @@ def test_scoping_in_callbacks
       model.class_eval do
         define_method :after_create_callback do
           # We don't want to be in the #children scope here when creating the child
-          self.parent
+          parent
           self.parent_id = record.id if record
-          self.root
+          root
         end
       end
 
diff --git a/test/concerns/setter_test.rb b/test/concerns/setter_test.rb
index cc1e8479..adfccbb6 100644
--- a/test/concerns/setter_test.rb
+++ b/test/concerns/setter_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class IntegrityCheckingAndRestaurationTest < ActiveSupport::TestCase
diff --git a/test/concerns/sort_by_ancestry_test.rb b/test/concerns/sort_by_ancestry_test.rb
index 768d2809..03a34448 100644
--- a/test/concerns/sort_by_ancestry_test.rb
+++ b/test/concerns/sort_by_ancestry_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class SortByAncestryTest < ActiveSupport::TestCase
@@ -5,7 +7,7 @@ class SortByAncestryTest < ActiveSupport::TestCase
   # This highlights where/why a non-correct sorting order is returned
   CORRECT = (ENV["CORRECT"] == "true")
 
-  RANK_SORT = -> (a, b) { a.rank <=> b.rank }
+  RANK_SORT = ->(a, b) { a.rank <=> b.rank }
 
   # tree is of the form:
   #   - n1
@@ -17,7 +19,7 @@ class SortByAncestryTest < ActiveSupport::TestCase
   # @returns [Array<model>] list of nodes
   def build_tree(model)
     # inflate the node id to test id wrap around edge cases
-    ENV["NODES"].to_i.times { model.create!.destroy } if ENV["NODES"]
+    ENV["NODES"]&.to_i&.times { model.create!.destroy }
 
     n1 = model.create!
     n2 = model.create!(:parent => n1)
@@ -57,7 +59,7 @@ def test_sort_by_ancestry_no_parents_siblings
   end
 
   # TODO: thinking about dropping this one
-  # only keep if we can find a 
+  # only keep if we can find a way to sort in the db
   def test_sort_by_ancestry_no_parents_same_level
     AncestryTestDatabase.with_model do |model|
       _, _, n3, n4, n5, _ = build_tree(model)
@@ -116,7 +118,7 @@ def test_sort_by_ancestry_missing_parent_middle_of_tree
   def build_ranked_tree(model)
     # inflate the node id to test id wrap around edge cases
     # NODES=4..9 seem like edge cases
-    ENV["NODES"].to_i.times { model.create!.destroy } if ENV["NODES"]
+    ENV["NODES"]&.to_i&.times { model.create!.destroy }
 
     n1 = model.create!(:rank => 0)
     n2 = model.create!(:rank => 1)
diff --git a/test/concerns/sti_support_test.rb b/test/concerns/sti_support_test.rb
index 2911e81c..123f481f 100644
--- a/test/concerns/sti_support_test.rb
+++ b/test/concerns/sti_support_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class StiSupportTest < ActiveSupport::TestCase
@@ -65,7 +67,7 @@ def test_sti_support_with_from_subclass
 
   def test_sti_support_for_counter_cache
     AncestryTestDatabase.with_model :counter_cache => true, :extra_columns => {:type => :string} do |model|
-      # NOTE had to use subclasses other than Subclass1/Subclass2 from above
+      # NOTE: had to use subclasses other than Subclass1/Subclass2 from above
       # due to (I think) Rails caching those STI classes and that not getting
       # reset between specs
 
diff --git a/test/concerns/touching_test.rb b/test/concerns/touching_test.rb
index be18e746..2b912416 100644
--- a/test/concerns/touching_test.rb
+++ b/test/concerns/touching_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class TouchingTest < ActiveSupport::TestCase
@@ -6,7 +8,6 @@ def test_touch_option_disabled
       :extra_columns => {:name => :string, :updated_at => :datetime},
       :touch => false
     ) do |model|
-
       wayback = Time.new(1984)
       recently = Time.now - 1.minute
 
@@ -25,7 +26,6 @@ def test_touch_option_enabled_propagates_with_modification
       :extra_columns => {:updated_at => :datetime},
       :touch => true
     ) do |model|
-
       way_back = Time.new(1984)
       recently = Time.now - 1.minute
 
@@ -52,7 +52,6 @@ def test_touch_option_enabled_propagates_with_modification
 
   def test_touch_propogates_multiple_levels
     AncestryTestDatabase.with_model(:extra_columns => {:name => :string, :updated_at => :datetime}, :touch => true) do |model|
-
       way_back = Time.new(1984)
       recently = Time.now - 1.minute
 
@@ -82,7 +81,6 @@ def test_touch_option_enabled_doesnt_propagate_without_modification
       :extra_columns => {:updated_at => :datetime},
       :touch => true
     ) do |model|
-
       way_back = Time.new(1984)
       recently = Time.now - 1.minute
 
@@ -105,7 +103,6 @@ def test_touch_option_with_scope
       :extra_columns => {:updated_at => :datetime},
       :touch => true
     ) do |model|
-
       way_back = Time.new(1984)
       recently = Time.now - 1.minute
 
diff --git a/test/concerns/tree_navigation_test.rb b/test/concerns/tree_navigation_test.rb
index ad8b2afc..be61967d 100644
--- a/test/concerns/tree_navigation_test.rb
+++ b/test/concerns/tree_navigation_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 # this is testing attribute getters
@@ -7,15 +9,15 @@ class TreeNavigationTest < ActiveSupport::TestCase
   # across: |siblings|subtree    |path     |
   ATTRIBUTE_MATRIX = {
     root:        {attribute_id:  :root_id},
-    parent:      {attribute_id:  :parent_id,     exists: :has_parent?, db: true},
-    ancestors:   {attribute_ids: :ancestor_ids,  exists: :ancestors?,  db: true},
-    children:    {attribute_ids: :child_ids,     exists: :children?},
+    parent:      {attribute_id:  :parent_id,    exists: :has_parent?, db: true},
+    ancestors:   {attribute_ids: :ancestor_ids, exists: :ancestors?,  db: true},
+    children:    {attribute_ids: :child_ids,    exists: :children?},
     descendants: {attribute_ids: :descendant_ids},
     indirects:   {attribute_ids: :indirect_ids},
-    siblings:    {attribute_ids: :sibling_ids,   exists: :siblings?},
+    siblings:    {attribute_ids: :sibling_ids,  exists: :siblings?},
     subtree:     {attribute_ids: :subtree_ids},
-    path:        {attribute_ids: :path_ids, db: true},
-  }
+    path:        {attribute_ids: :path_ids, db: true}
+  }.freeze
   # NOTE: has_ancestors? is an alias for parent? / ancestors? but not tested
 
   # class level getters are in test/concerns/scopes_test.rb
@@ -194,7 +196,8 @@ def test_node_in_database_children
 
       # in database (again - but in a different hierarchy)
       node11.save!
-      node1.reload ; node2.reload
+      node1.reload
+      node2.reload
       # are these necessary?
       # do we want this to work without?
 
@@ -242,19 +245,26 @@ def update_descendants_with_new_ancestry
             raise "callback disabled for #{id}" if id == 2
           else
             raise "callback eabled for #{id}" if id != 2
+
             # want to make sure we're pointing at the correct nodes
             actual = unscoped_descendants_before_last_save.order(:id).map(&:id)
             raise "unscoped_descendants_before_last_save was #{actual}" unless actual == [3, 4, 5]
+
             actual = path_ids_before_last_save
             raise "bad path_ids(before) is #{actual}" unless actual == [1, 2]
+
             actual = path_ids
             raise "bad path_ids is #{actual}" unless actual == [6, 2]
+
             actual = parent_id_before_last_save
             raise "bad parent_id(before) id #{actual}" unless actual == 1
+
             actual = parent_id
             raise "bad parent_id(before) id #{actual}" unless actual == 6
+
             actual = ancestor_ids_before_last_save
             raise "bad ancestor_ids(before) id #{actual}" unless actual == [1]
+
             actual = ancestor_ids
             raise "bad ancestor_ids(before) id #{actual}" unless actual == [6]
           end
@@ -308,7 +318,7 @@ def assert_attribute(node, attribute_name, value, db: :value, exists: :value)
   # @param value [Array] expected output
   # @param attribute_name [Symbol] attribute to test
   # @param exists [true|false] test the exists "attribute? (default values.present?)
-  # @param db [Array[AR]]  value that should be reflected _in_database (default: use values) 
+  # @param db [Array[AR]]  value that should be reflected _in_database (default: use values)
   #                        skips if not supported in matrix
   def assert_attributes(node, attribute_name, values, db: :values, exists: :values)
     attribute_ids = ATTRIBUTE_MATRIX[attribute_name][:attribute_ids]
diff --git a/test/concerns/tree_predicate_test.rb b/test/concerns/tree_predicate_test.rb
index c57d6304..38be4841 100644
--- a/test/concerns/tree_predicate_test.rb
+++ b/test/concerns/tree_predicate_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../environment'
 
 class TreePredicateTest < ActiveSupport::TestCase
@@ -19,7 +21,7 @@ def test_tree_predicates
         # Children assertions
         assert root.has_children?
         assert !root.is_childless?
-        assert children.map { |n| n.is_childless? }.all?
+        assert children.map(&:is_childless?).all?
         assert children.map { |n| !root.child_of?(n) }.all?
         assert children.map { |n| n.child_of?(root) }.all?
         # Siblings assertions
diff --git a/test/environment.rb b/test/environment.rb
index dc3e848e..f5ed1b0e 100644
--- a/test/environment.rb
+++ b/test/environment.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rubygems'
 require 'bundler/setup'
 
@@ -24,7 +26,7 @@ class AncestryTestDatabase
   def self.setup
     # Silence I18n and Activerecord logging
     I18n.enforce_available_locales = false if I18n.respond_to? :enforce_available_locales=
-    ActiveRecord::Base.logger = Logger.new(STDERR)
+    ActiveRecord::Base.logger = Logger.new($stderr)
     ActiveRecord::Base.logger.level = Logger::Severity::UNKNOWN
 
     # Assume Travis CI database config if no custom one exists
@@ -35,14 +37,15 @@ def self.setup
                end
 
     # Setup database connection
-    all_config = if YAML.respond_to?(:safe_load_file)
-      YAML.safe_load_file(filename, aliases: true)
-    else
-      YAML.load_file(filename)
-    end
+    all_config =
+      if YAML.respond_to?(:safe_load_file)
+        YAML.safe_load_file(filename, aliases: true)
+      else
+        YAML.load_file(filename)
+      end
     config = all_config[db_type]
     if config.blank?
-      $stderr.puts "","","ERROR: Could not find '#{db_type}' in #{filename}"
+      $stderr.puts "", "", "ERROR: Could not find '#{db_type}' in #{filename}"
       $stderr.puts "Pick from: #{all_config.keys.join(", ")}", "", ""
       exit(1)
     end
@@ -59,13 +62,12 @@ def self.setup
 
       puts "testing #{db_type} #{Ancestry.default_update_strategy == :sql ? "(sql) " : ""}(with #{column_type} #{ancestry_column})"
       puts "column format: #{Ancestry.default_ancestry_format} options: #{column_options.inspect}"
-
-    rescue => err
+    rescue StandardError => e
       if ENV["CI"]
         raise
       else
         puts "\nSkipping tests for '#{db_type}'"
-        puts "  #{err}\n\n"
+        puts "  #{e}\n\n"
         exit 0
       end
     end
@@ -102,18 +104,18 @@ def self.column_options(force_allow_nil: false)
       if column_type == "string"
         {
           :collation => ancestry_collation == "default" ? nil : ancestry_collation,
-          :null  => materialized_path2? ? false : true
+          :null  => !materialized_path2?
         }
       else
         {
           :limit => 3000,
-          :null  => materialized_path2? ? false : true
+          :null  => !materialized_path2?
         }
       end
     force_allow_nil ? @column_options.merge(:null => true) : @column_options
   end
 
-  def self.with_model options = {}
+  def self.with_model(options = {})
     depth                = options.delete(:depth) || 0
     width                = options.delete(:width) || 0
     skip_ancestry        = options.delete(:skip_ancestry)
@@ -121,7 +123,7 @@ def self.with_model options = {}
     default_scope_params = options.delete(:default_scope_params)
 
     options[:ancestry_column] ||= ancestry_column
-    table_options={}
+    table_options = {}
     table_options[:id] = options.delete(:id) if options.key?(:id)
 
     ActiveRecord::Base.connection.create_table 'test_nodes', **table_options do |table|
@@ -145,13 +147,13 @@ def self.with_model options = {}
         table.integer counter_cache_column, default: 0, null: false
       end
 
-      extra_columns.each do |name, type|
+      extra_columns&.each do |name, type|
         table.send type, name
-      end unless extra_columns.nil?
+      end
     end
 
     testmethod = caller[0][/`.*'/][1..-2]
-    model_name = testmethod.camelize + "TestNode"
+    model_name = "#{testmethod.camelize}TestNode"
 
     begin
       model = Class.new(ActiveRecord::Base)
@@ -177,13 +179,15 @@ def self.with_model options = {}
     end
   end
 
-  def self.create_test_nodes model, depth, width, parent = nil
-    unless depth == 0
+  def self.create_test_nodes(model, depth, width, parent = nil)
+    if depth == 0
+      []
+    else
       Array.new width do
         node = model.create!(:parent => parent)
         [node, create_test_nodes(model, depth - 1, width, node)]
       end
-    else; []; end
+    end
   end
 
   def self.postgres?
@@ -192,9 +196,9 @@ def self.postgres?
 
   def self.materialized_path2?
     return @materialized_path2 if defined?(@materialized_path2)
+
     @materialized_path2 = (ENV["FORMAT"] == "materialized_path2")
   end
-  private
 
   def self.db_type
     ENV["DB"].presence || "sqlite3"
diff --git a/test/test_helpers.rb b/test/test_helpers.rb
index 61caee1c..74b9a405 100644
--- a/test/test_helpers.rb
+++ b/test/test_helpers.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module TestHelpers
   def assert_ancestry(node, value, child: :skip, db: :value)
     column_name = node.class.ancestry_column