Remove deprecation warnings for rails 6

In rails 6 there is deprecation warning for `update_attributes!` method.
It will be replaced with `update!` method. In order to remove
deprecation I have wrapped method call inside `rails_api` facade.

.rubocop_todo.yml

@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2020-04-19 08:04:49 +0200 using RuboCop version 0.82.0.
+# on 2020-05-03 14:16:43 +0200 using RuboCop version 0.82.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -11,12 +11,12 @@
 Metrics/AbcSize:
   Max: 44
 
-# Offense count: 1
+# Offense count: 4
 # Configuration parameters: CountComments, ExcludedMethods.
 Metrics/MethodLength:
   Max: 28
 
-# Offense count: 12
+# Offense count: 13
 Style/Documentation:
   Exclude:
     - 'spec/**/*'
@@ -26,6 +26,7 @@ Style/Documentation:
     - 'lib/acts_as_messageable/model.rb'
     - 'lib/acts_as_messageable/rails3.rb'
     - 'lib/acts_as_messageable/rails4.rb'
+    - 'lib/acts_as_messageable/rails6.rb'
     - 'lib/acts_as_messageable/railtie.rb'
     - 'lib/acts_as_messageable/relation.rb'
     - 'lib/acts_as_messageable/scopes.rb'

lib/acts_as_messageable.rb

@@ -7,9 +7,12 @@ module ActsAsMessageable
   autoload :Relation, 'acts_as_messageable/relation'
   autoload :Rails3, 'acts_as_messageable/rails3'
   autoload :Rails4, 'acts_as_messageable/rails4'
+  autoload :Rails6, 'acts_as_messageable/rails6'
 
   def self.rails_api
-    if Rails::VERSION::MAJOR >= 4
+    if Rails::VERSION::MAJOR >= 6
+      Rails6
+    elsif Rails::VERSION::MAJOR >= 4
       Rails4
     else
       Rails3

lib/acts_as_messageable/message.rb

@@ -27,16 +27,16 @@ def opened?
     end
 
     def open
-      update_attributes!(opened_at: DateTime.now)
-      update_attributes!(opened: true)
+      ActsAsMessageable.rails_api.new(self).update_attributes!(opened_at: DateTime.now)
+      ActsAsMessageable.rails_api.new(self).update_attributes!(opened: true)
     end
 
     alias mark_as_read open
     alias read open
 
     def close
-      update_attributes!(opened_at: nil)
-      update_attributes!(opened: false)
+      ActsAsMessageable.rails_api.new(self).update_attributes!(opened_at: nil)
+      ActsAsMessageable.rails_api.new(self).update_attributes!(opened: false)
     end
 
     alias mark_as_unread close

lib/acts_as_messageable/model.rb

@@ -155,7 +155,7 @@ def delete_message(message)
           raise "#{current_user} can't delete this message"
         end
 
-        message.update_attributes!(attribute => true)
+        ActsAsMessageable.rails_api.new(message).update_attributes!(attribute => true)
       end
 
       # Mark message as restored
@@ -171,7 +171,7 @@ def restore_message(message)
           raise "#{current_user} can't restore this message"
         end
 
-        message.update_attributes!(attribute => false)
+        ActsAsMessageable.rails_api.new(message).update_attributes!(attribute => false)
       end
     end
   end

lib/acts_as_messageable/rails4.rb

@@ -6,6 +6,8 @@ def initialize(subject)
       @subject = subject
     end
 
+    def attr_accessible(*); end
+
     def default_scope(order_by)
       @subject.send(:default_scope) { order(order_by) }
     end
@@ -14,14 +16,12 @@ def scoped
       @subject.scope
     end
 
-    def attr_accessible(*); end
-
     def method_missing(name, *args)
       @subject.send(name, *args) || super
     end
 
     def respond_to_missing?(method_name, include_private = false)
-      %w[default_scope scoped].include?(method_name) || super
+      %w[default_scope scoped attr_accessible].include?(method_name) || super
     end
   end
 end

lib/acts_as_messageable/rails6.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module ActsAsMessageable
+  class Rails6
+    def initialize(subject)
+      @subject = subject
+    end
+
+    def attr_accessible(*); end
+
+    def default_scope(order_by)
+      @subject.send(:default_scope) { order(order_by) }
+    end
+
+    def scoped
+      @subject.scope
+    end
+
+    def update_attributes!(*args)
+      @subject.update!(*args)
+    end
+
+    def method_missing(name, *args)
+      @subject.send(name, *args) || super
+    end
+
+    def respond_to_missing?(method_name, include_private = false)
+      %w[attr_accessible default_scope scoped update_attributes!].include?(method_name) || super
+    end
+  end
+end