drop rails < 5

lib/paperclip/callback_compatability.rb

@@ -5,45 +5,15 @@ module Paperclip
     module_function
 
     def install_to(base)
-      mod = base.respond_to?(:set_callback) ? Rails3 : Rails21
-      base.extend(mod::Defining)
-      base.send(:include, mod::Running)
+      raise "#{base} does not respond to set_callback" unless base.respond_to?(:set_callback)
+
+      base.extend(Defining)
+      base.send(:include, Running)
     end
 
-    module Rails21
     module Defining
-        def define_paperclip_callbacks(*args)
-          args.each do |callback|
-            define_callbacks("before_#{callback}")
-            define_callbacks("after_#{callback}")
-          end
-        end
-      end
-
-      module Running
-        def run_paperclip_callbacks(callback, _opts = nil)
-          # The overall structure of this isn't ideal since after callbacks run even if
-          # befores return false. But this is how rails 3's callbacks work, unfortunately.
-          yield if run_callbacks(:"before_#{callback}") { |result, _object| result == false } != false
-          run_callbacks(:"after_#{callback}") { |result, _object| result == false }
-        end
-      end
-    end
-
-    module Rails3
-      module Defining
-        rails_version = Gem::Version.new(ActiveSupport::VERSION::STRING)
-        CALLBACK_OPTIONS =
-          if rails_version >= Gem::Version.new('5.0')
-            {}
-          elsif rails_version >= Gem::Version.new('4.1')
-            { terminator: ->(_target, result) { result == false } }
-          else
-            { terminator: 'result == false' }
-          end
-
       def define_paperclip_callbacks(*callbacks)
-          define_callbacks(*callbacks.flatten, CALLBACK_OPTIONS)
+        define_callbacks(*callbacks.flatten, {})
         callbacks.map(&:to_sym).each do |callback|
           define_singleton_method "before_#{callback}" do |*args, &blk|
             set_callback(callback, :before, *args, &blk)
@@ -63,5 +33,3 @@ module Paperclip
     end
   end
 end
-end
-

paperclip.gemspec

@@ -19,7 +19,7 @@ Gem::Specification.new do |s|
   s.rubyforge_project = %q{paperclip}
   s.summary = %q{File attachments as attributes for ActiveRecord}
 
-  s.add_dependency 'activesupport', '< 7.2'
+  s.add_dependency 'activesupport', [">= 5.0", '< 7.2']
   s.add_dependency 'addressable'
   s.add_dependency 'fastimage'
 end

test/test_helper.rb

@@ -99,6 +99,9 @@ def rebuild_class(options = {})
 end
 
 class FakeModel
+  def self.set_callback(...)
+  end
+
   include Paperclip
 
   attr_accessor :avatar_file_name,