A missing content_type validator shows deprecation warning

lib/paperclip/attachment.rb

 # encoding: utf-8
 require 'uri'
 require 'paperclip/url_generator'
+require 'active_support/deprecation'
 
 module Paperclip
   # The Attachment class manages the files for a given attachment. It saves
@@ -93,6 +94,7 @@ module Paperclip
     #   new_user.avatar = old_user.avatar
     def assign uploaded_file
       ensure_required_accessors!
+      ensure_required_validations!
       file = Paperclip.io_adapters.for(uploaded_file)
 
       return nil if not file.assignment?
@@ -385,6 +387,19 @@ module Paperclip
       @options[:path].respond_to?(:call) ? @options[:path].call(self) : @options[:path]
     end
 
+    def active_validator_classes
+      @instance.class.validators.map(&:class)
+    end
+
+    def ensure_required_validations!
+      if ! active_validator_classes.include?(Paperclip::Validators::AttachmentContentTypeValidator)
+        ActiveSupport::Deprecation.warn(
+          "You must define a content_type validator to ensure you only accept files of the correct type. Failure to do so will raise an error in Paperclip versions >= 4.0"
+        )
+        # raise Paperclip::Errors::NoContentTypeValidator.new('you must define a content type validation')
+      end
+    end
+
     def ensure_required_accessors! #:nodoc:
       %w(file_name).each do |field|
         unless @instance.respond_to?("#{name}_#{field}") && @instance.respond_to?("#{name}_#{field}=")

lib/paperclip/errors.rb

@@ -13,6 +13,10 @@ module Paperclip
     class CommandNotFoundError < Paperclip::Error
     end
 
+    # Thrown when no content_type validation exists
+    # class NoContentTypeValidator < Paperclip::Error
+    # end
+
     # Will be thrown when ImageMagic cannot determine the uploaded file's
     # metadata, usually this would mean the file is not an image.
     class NotIdentifiedByImageMagickError < Paperclip::Error

test/helper.rb

@@ -40,6 +40,7 @@ class Test::Unit::TestCase
       Rails.stubs(:root).returns(Pathname.new(ROOT).join('tmp'))
       Rails.stubs(:env).returns('test')
       Rails.stubs(:const_defined?).with(:Railtie).returns(false)
+      ActiveSupport::Deprecation.silenced = true
     end
   end
 

test/schema_test.rb

@@ -15,6 +15,9 @@ class SchemaTest < Test::Unit::TestCase
 
   context "within table definition" do
     context "using #has_attached_file" do
+      setup do
+        ActiveSupport::Deprecation.silenced = false
+      end
       should "create attachment columns" do
         Dummy.connection.create_table :dummies, :force => true do |t|
           ActiveSupport::Deprecation.silence do
@@ -122,6 +125,9 @@ class SchemaTest < Test::Unit::TestCase
       end
 
       context "using #drop_attached_file" do
+        setup do
+          ActiveSupport::Deprecation.silenced = false
+        end
         should "remove the attachment columns" do
           ActiveSupport::Deprecation.silence do
             Dummy.connection.drop_attached_file :dummies, :avatar

test/validators_test.rb

 require './test/helper'
 
 class ValidatorsTest < Test::Unit::TestCase
+  include ActiveSupport::Testing::Deprecation
+
   def setup
     rebuild_model
   end
@@ -58,4 +60,41 @@ class ValidatorsTest < Test::Unit::TestCase
       assert_equal [], dummy.errors.keys
     end
   end
+
+  context 'when no content_type validation exists' do
+    setup do
+      ActiveSupport::Deprecation.silenced = false
+    end
+
+    should 'emit a deprecation warning' do
+      assert_deprecated do
+        Dummy.new(:avatar => File.new(fixture_file("12k.png")))
+      end
+    end
+
+    # should 'raise an error' do
+    #   assert_raises(Paperclip::Errors::NoContentTypeValidator) do 
+    #     Dummy.new(:avatar => File.new(fixture_file("12k.png")))
+    #   end
+    # end
+  end
+
+  context 'when a content_type validation exists' do
+    setup do
+      Dummy.validates_attachment :avatar, :content_type => { :content_type => "image/jpeg" }
+      ActiveSupport::Deprecation.silenced = false
+    end
+
+    should 'not emit a deprecation warning' do
+      assert_not_deprecated do
+        Dummy.new(:avatar => File.new(fixture_file("12k.png")))
+      end
+    end
+
+    # should 'not raise an error' do
+    #   assert_nothing_raised(Paperclip::Errors::NoContentTypeValidator) do 
+    #     Dummy.new(:avatar => File.new(fixture_file("12k.png")))
+    #   end
+    # end
+  end
 end