Refactor RailsShim

* Satisfy Rubocop
* Alphabetize methods
* Use `class << self` instead of `self.` so that we can privatize one of
  the methods

lib/shoulda/matchers/rails_shim.rb

@@ -2,31 +2,55 @@ module Shoulda
   module Matchers
     # @private
     class RailsShim
-      def self.verb_for_update
-        if action_pack_gte_4_1?
-          :patch
-        else
-          :put
-        end
+      class << self
+      def active_record_major_version
+        ::ActiveRecord::VERSION::MAJOR
       end
 
-      def self.type_cast_default_for(model, column)
-        if model.respond_to?(:column_defaults)
-          # Rails 4.2
-          model.column_defaults[column.name]
+      def action_pack_gte_4_1?
+        Gem::Requirement.new('>= 4.1').satisfied_by?(action_pack_version)
+      end
+
+      def action_pack_version
+        Gem::Version.new(::ActionPack::VERSION::STRING)
+      end
+
+      def generate_validation_message(
+        record,
+        attribute,
+        type,
+        model_name,
+        options
+      )
+        if record && record.errors.respond_to?(:generate_message)
+          record.errors.generate_message(attribute.to_sym, type, options)
         else
-          column.default
+          simply_generate_validation_message(
+            attribute,
+            type,
+            model_name,
+            options,
+          )
         end
+      rescue RangeError
+        simply_generate_validation_message(
+          attribute,
+          type,
+          model_name,
+          options,
+        )
       end
 
-      def self.serialized_attributes_for(model)
+      def serialized_attributes_for(model)
         if defined?(::ActiveRecord::Type::Serialized)
           # Rails 5+
-          model.columns.select do |column|
+          serialized_columns = model.columns.select do |column|
             model.type_for_attribute(column.name).is_a?(
               ::ActiveRecord::Type::Serialized,
             )
-          end.inject({}) do |hash, column|
+          end
+
+          serialized_columns.inject({}) do |hash, column|
             hash[column.name.to_s] = model.type_for_attribute(column.name).coder
             hash
           end
@@ -35,49 +59,24 @@ def self.serialized_attributes_for(model)
         end
       end
 
-      def self.generate_validation_message(record, attribute, type, model_name, options)
-        if record && record.errors.respond_to?(:generate_message)
-          record.errors.generate_message(attribute.to_sym, type, options)
+      def type_cast_default_for(model, column)
+        if model.respond_to?(:column_defaults)
+          # Rails 4.2
+          model.column_defaults[column.name]
         else
-          simply_generate_validation_message(attribute, type, model_name, options)
+          column.default
         end
-      rescue RangeError
-        simply_generate_validation_message(attribute, type, model_name, options)
-      end
-
-      def self.simply_generate_validation_message(attribute, type, model_name, options)
-        default_translation_keys = [
-          :"activerecord.errors.models.#{model_name}.#{type}",
-          :"activerecord.errors.messages.#{type}",
-          :"errors.attributes.#{attribute}.#{type}",
-          :"errors.messages.#{type}"
-        ]
-        primary_translation_key = :"activerecord.errors.models.#{model_name}.attributes.#{attribute}.#{type}"
-        translate_options = { default: default_translation_keys }.merge(options)
-        I18n.translate(primary_translation_key, translate_options)
       end
 
-      def self.tables_and_views(connection)
+      def tables_and_views(connection)
         if active_record_major_version >= 5
           connection.data_sources
         else
           connection.tables
         end
       end
 
-      def self.active_record_major_version
-        ::ActiveRecord::VERSION::MAJOR
-      end
-
-      def self.action_pack_gte_4_1?
-        Gem::Requirement.new('>= 4.1').satisfied_by?(action_pack_version)
-      end
-
-      def self.action_pack_version
-        Gem::Version.new(::ActionPack::VERSION::STRING)
-      end
-
-      def self.make_controller_request(context, verb, action, request_params)
+      def make_controller_request(context, verb, action, request_params)
         params =
           if active_record_major_version >= 5
             { params: request_params }
@@ -87,6 +86,41 @@ def self.make_controller_request(context, verb, action, request_params)
 
         context.__send__(verb, action, params)
       end
+
+      def verb_for_update
+        if action_pack_gte_4_1?
+          :patch
+        else
+          :put
+        end
+      end
+
+      private
+
+      def simply_generate_validation_message(
+        attribute,
+        type,
+        model_name,
+        options
+      )
+        default_translation_keys = [
+          :"activerecord.errors.models.#{model_name}.#{type}",
+          :"activerecord.errors.messages.#{type}",
+          :"errors.attributes.#{attribute}.#{type}",
+          :"errors.messages.#{type}"
+        ]
+        primary_translation_key = [
+          :activerecord,
+          :errors,
+          :models,
+          model_name,
+          :attributes,
+          attribute,
+          type,
+        ]
+        translate_options = { default: default_translation_keys }.merge(options)
+        I18n.translate(primary_translation_key, translate_options)
+      end
     end
   end
 end