`ActiveJob::QueueAdapters::*` are no longer singletons

18 files changed, 173 insertions, 152 deletions

diff --git a/activejob/lib/active_job/logging.rb b/activejob/lib/active_job/logging.rb
index cd29e6908e..54774db601 100644
--- a/activejob/lib/active_job/logging.rb
+++ b/activejob/lib/active_job/logging.rb
@@ -81,7 +81,7 @@ module ActiveJob
 
       private
         def queue_name(event)
-          event.payload[:adapter].name.demodulize.remove('Adapter') + "(#{event.payload[:job].queue_name})"
+          event.payload[:adapter].class.name.demodulize.remove('Adapter') + "(#{event.payload[:job].queue_name})"
         end
 
         def args_info(job)
diff --git a/activejob/lib/active_job/queue_adapter.rb b/activejob/lib/active_job/queue_adapter.rb
index aa3ebdbc7b..23b5f7de75 100644
--- a/activejob/lib/active_job/queue_adapter.rb
+++ b/activejob/lib/active_job/queue_adapter.rb
@@ -14,20 +14,40 @@ module ActiveJob
       # Specify the backend queue provider. The default queue adapter
       # is the :inline queue. See QueueAdapters for more
       # information.
-      def queue_adapter=(name_or_adapter)
-        @@queue_adapter = \
-          case name_or_adapter
-          when Symbol, String
-            load_adapter(name_or_adapter)
+      def queue_adapter=(name_or_adapter_or_class)
+        case name_or_adapter_or_class
+        when Symbol, String
+          self.queue_adapter = load_adapter(name_or_adapter_or_class)
+        else
+          @@queue_adapter = if queue_adapter?(name_or_adapter_or_class)
+            name_or_adapter_or_class
+          elsif queue_adapter_class?(name_or_adapter_or_class)
+            ActiveSupport::Deprecation.warn "Passing an adapter class is deprecated " \
+            "and will be removed in Rails 5.1. Please pass an adapter name " \
+            "(.queue_adapter = :#{name_or_adapter_or_class.name.demodulize.remove('Adapter').underscore}) " \
+            "or an instance (.queue_adapter = #{name_or_adapter_or_class.name}.new) instead."
+            name_or_adapter_or_class.new
           else
-            name_or_adapter if name_or_adapter.respond_to?(:enqueue)
+            raise ArgumentError
           end
+        end
       end
 
       private
-        def load_adapter(name)
-          "ActiveJob::QueueAdapters::#{name.to_s.camelize}Adapter".constantize
-        end
+
+      QUEUE_ADAPTER_METHODS = [:enqueue, :enqueue_at].freeze
+
+      def queue_adapter?(object)
+        QUEUE_ADAPTER_METHODS.all? { |meth| object.respond_to?(meth) }
+      end
+
+      def queue_adapter_class?(object)
+        object.is_a?(Class) && QUEUE_ADAPTER_METHODS.all? { |meth| object.public_method_defined?(meth) }
+      end
+
+      def load_adapter(name)
+        "ActiveJob::QueueAdapters::#{name.to_s.camelize}Adapter".constantize.new
+      end
     end
   end
 end
diff --git a/activejob/lib/active_job/queue_adapters/backburner_adapter.rb b/activejob/lib/active_job/queue_adapters/backburner_adapter.rb
index 2453d065de..17703e3e41 100644
--- a/activejob/lib/active_job/queue_adapters/backburner_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/backburner_adapter.rb
@@ -13,15 +13,13 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :backburner
     class BackburnerAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          Backburner::Worker.enqueue JobWrapper, [ job.serialize ], queue: job.queue_name
-        end
+      def enqueue(job) #:nodoc:
+        Backburner::Worker.enqueue JobWrapper, [ job.serialize ], queue: job.queue_name
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          delay = timestamp - Time.current.to_f
-          Backburner::Worker.enqueue JobWrapper, [ job.serialize ], queue: job.queue_name, delay: delay
-        end
+      def enqueue_at(job, timestamp) #:nodoc:
+        delay = timestamp - Time.current.to_f
+        Backburner::Worker.enqueue JobWrapper, [ job.serialize ], queue: job.queue_name, delay: delay
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/delayed_job_adapter.rb b/activejob/lib/active_job/queue_adapters/delayed_job_adapter.rb
index 69d9e70de3..852a6ee326 100644
--- a/activejob/lib/active_job/queue_adapters/delayed_job_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/delayed_job_adapter.rb
@@ -13,14 +13,12 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :delayed_job
     class DelayedJobAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          Delayed::Job.enqueue(JobWrapper.new(job.serialize), queue: job.queue_name)
-        end
+      def enqueue(job) #:nodoc:
+        Delayed::Job.enqueue(JobWrapper.new(job.serialize), queue: job.queue_name)
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          Delayed::Job.enqueue(JobWrapper.new(job.serialize), queue: job.queue_name, run_at: Time.at(timestamp))
-        end
+      def enqueue_at(job, timestamp) #:nodoc:
+        Delayed::Job.enqueue(JobWrapper.new(job.serialize), queue: job.queue_name, run_at: Time.at(timestamp))
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/inline_adapter.rb b/activejob/lib/active_job/queue_adapters/inline_adapter.rb
index e25d88e723..1d06324c18 100644
--- a/activejob/lib/active_job/queue_adapters/inline_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/inline_adapter.rb
@@ -9,14 +9,12 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :inline
     class InlineAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          Base.execute(job.serialize)
-        end
+      def enqueue(job) #:nodoc:
+        Base.execute(job.serialize)
+      end
 
-        def enqueue_at(*) #:nodoc:
-          raise NotImplementedError.new("Use a queueing backend to enqueue jobs in the future. Read more at http://guides.rubyonrails.org/active_job_basics.html")
-        end
+      def enqueue_at(*) #:nodoc:
+        raise NotImplementedError.new("Use a queueing backend to enqueue jobs in the future. Read more at http://guides.rubyonrails.org/active_job_basics.html")
       end
     end
   end
diff --git a/activejob/lib/active_job/queue_adapters/qu_adapter.rb b/activejob/lib/active_job/queue_adapters/qu_adapter.rb
index 30aa5a4670..94584ef9d8 100644
--- a/activejob/lib/active_job/queue_adapters/qu_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/qu_adapter.rb
@@ -16,16 +16,14 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :qu
     class QuAdapter
-      class << self
-        def enqueue(job, *args) #:nodoc:
-          Qu::Payload.new(klass: JobWrapper, args: [job.serialize]).tap do |payload|
-            payload.instance_variable_set(:@queue, job.queue_name)
-          end.push
-        end
+      def enqueue(job, *args) #:nodoc:
+        Qu::Payload.new(klass: JobWrapper, args: [job.serialize]).tap do |payload|
+          payload.instance_variable_set(:@queue, job.queue_name)
+        end.push
+      end
 
-        def enqueue_at(job, timestamp, *args) #:nodoc:
-          raise NotImplementedError
-        end
+      def enqueue_at(job, timestamp, *args) #:nodoc:
+        raise NotImplementedError
       end
 
       class JobWrapper < Qu::Job #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/que_adapter.rb b/activejob/lib/active_job/queue_adapters/que_adapter.rb
index e501fe0368..84cc2845b0 100644
--- a/activejob/lib/active_job/queue_adapters/que_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/que_adapter.rb
@@ -15,14 +15,12 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :que
     class QueAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          JobWrapper.enqueue job.serialize, queue: job.queue_name
-        end
+      def enqueue(job) #:nodoc:
+        JobWrapper.enqueue job.serialize, queue: job.queue_name
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          JobWrapper.enqueue job.serialize, queue: job.queue_name, run_at: Time.at(timestamp)
-        end
+      def enqueue_at(job, timestamp) #:nodoc:
+        JobWrapper.enqueue job.serialize, queue: job.queue_name, run_at: Time.at(timestamp)
       end
 
       class JobWrapper < Que::Job #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/queue_classic_adapter.rb b/activejob/lib/active_job/queue_adapters/queue_classic_adapter.rb
index 34c11a68b2..059754a87f 100644
--- a/activejob/lib/active_job/queue_adapters/queue_classic_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/queue_classic_adapter.rb
@@ -17,29 +17,27 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :queue_classic
     class QueueClassicAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          build_queue(job.queue_name).enqueue("#{JobWrapper.name}.perform", job.serialize)
-        end
+      def enqueue(job) #:nodoc:
+        build_queue(job.queue_name).enqueue("#{JobWrapper.name}.perform", job.serialize)
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          queue = build_queue(job.queue_name)
-          unless queue.respond_to?(:enqueue_at)
-            raise NotImplementedError, 'To be able to schedule jobs with queue_classic ' \
-              'the QC::Queue needs to respond to `enqueue_at(timestamp, method, *args)`. ' \
-              'You can implement this yourself or you can use the queue_classic-later gem.'
-          end
-          queue.enqueue_at(timestamp, "#{JobWrapper.name}.perform", job.serialize)
+      def enqueue_at(job, timestamp) #:nodoc:
+        queue = build_queue(job.queue_name)
+        unless queue.respond_to?(:enqueue_at)
+          raise NotImplementedError, 'To be able to schedule jobs with queue_classic ' \
+            'the QC::Queue needs to respond to `enqueue_at(timestamp, method, *args)`. ' \
+            'You can implement this yourself or you can use the queue_classic-later gem.'
         end
+        queue.enqueue_at(timestamp, "#{JobWrapper.name}.perform", job.serialize)
+      end
 
-        # Builds a <tt>QC::Queue</tt> object to schedule jobs on.
-        #
-        # If you have a custom <tt>QC::Queue</tt> subclass you'll need to subclass
-        # <tt>ActiveJob::QueueAdapters::QueueClassicAdapter</tt> and override the
-        # <tt>build_queue</tt> method.
-        def build_queue(queue_name)
-          QC::Queue.new(queue_name)
-        end
+      # Builds a <tt>QC::Queue</tt> object to schedule jobs on.
+      #
+      # If you have a custom <tt>QC::Queue</tt> subclass you'll need to subclass
+      # <tt>ActiveJob::QueueAdapters::QueueClassicAdapter</tt> and override the
+      # <tt>build_queue</tt> method.
+      def build_queue(queue_name)
+        QC::Queue.new(queue_name)
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/resque_adapter.rb b/activejob/lib/active_job/queue_adapters/resque_adapter.rb
index 88c6b48fef..417854afd8 100644
--- a/activejob/lib/active_job/queue_adapters/resque_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/resque_adapter.rb
@@ -26,18 +26,16 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :resque
     class ResqueAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          Resque.enqueue_to job.queue_name, JobWrapper, job.serialize
-        end
+      def enqueue(job) #:nodoc:
+        Resque.enqueue_to job.queue_name, JobWrapper, job.serialize
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          unless Resque.respond_to?(:enqueue_at_with_queue)
-            raise NotImplementedError, "To be able to schedule jobs with Resque you need the " \
-              "resque-scheduler gem. Please add it to your Gemfile and run bundle install"
-          end
-          Resque.enqueue_at_with_queue job.queue_name, timestamp, JobWrapper, job.serialize
+      def enqueue_at(job, timestamp) #:nodoc:
+        unless Resque.respond_to?(:enqueue_at_with_queue)
+          raise NotImplementedError, "To be able to schedule jobs with Resque you need the " \
+            "resque-scheduler gem. Please add it to your Gemfile and run bundle install"
         end
+        Resque.enqueue_at_with_queue job.queue_name, timestamp, JobWrapper, job.serialize
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb b/activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb
index 21005fc728..e02593ec9c 100644
--- a/activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb
@@ -15,22 +15,20 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :sidekiq
     class SidekiqAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          #Sidekiq::Client does not support symbols as keys
-          Sidekiq::Client.push \
-            'class' => JobWrapper,
-            'queue' => job.queue_name,
-            'args'  => [ job.serialize ]
-        end
+      def enqueue(job) #:nodoc:
+        #Sidekiq::Client does not support symbols as keys
+        Sidekiq::Client.push \
+          'class' => JobWrapper,
+          'queue' => job.queue_name,
+          'args'  => [ job.serialize ]
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          Sidekiq::Client.push \
-            'class' => JobWrapper,
-            'queue' => job.queue_name,
-            'args'  => [ job.serialize ],
-            'at'    => timestamp
-        end
+      def enqueue_at(job, timestamp) #:nodoc:
+        Sidekiq::Client.push \
+          'class' => JobWrapper,
+          'queue' => job.queue_name,
+          'args'  => [ job.serialize ],
+          'at'    => timestamp
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/sneakers_adapter.rb b/activejob/lib/active_job/queue_adapters/sneakers_adapter.rb
index 6d60a2f303..f5737487ca 100644
--- a/activejob/lib/active_job/queue_adapters/sneakers_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/sneakers_adapter.rb
@@ -16,19 +16,19 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :sneakers
     class SneakersAdapter
-      @monitor = Monitor.new
+      def initialize
+        @monitor = Monitor.new
+      end
 
-      class << self
-        def enqueue(job) #:nodoc:
-          @monitor.synchronize do
-            JobWrapper.from_queue job.queue_name
-            JobWrapper.enqueue ActiveSupport::JSON.encode(job.serialize)
-          end
+      def enqueue(job) #:nodoc:
+        @monitor.synchronize do
+          JobWrapper.from_queue job.queue_name
+          JobWrapper.enqueue ActiveSupport::JSON.encode(job.serialize)
         end
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          raise NotImplementedError
-        end
+      def enqueue_at(job, timestamp) #:nodoc:
+        raise NotImplementedError
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb b/activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb
index be9e7fd03a..64c93e8198 100644
--- a/activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb
@@ -18,14 +18,12 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :sucker_punch
     class SuckerPunchAdapter
-      class << self
-        def enqueue(job) #:nodoc:
-          JobWrapper.new.async.perform job.serialize
-        end
+      def enqueue(job) #:nodoc:
+        JobWrapper.new.async.perform job.serialize
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          raise NotImplementedError
-        end
+      def enqueue_at(job, timestamp) #:nodoc:
+        raise NotImplementedError
       end
 
       class JobWrapper #:nodoc:
diff --git a/activejob/lib/active_job/queue_adapters/test_adapter.rb b/activejob/lib/active_job/queue_adapters/test_adapter.rb
index fd7c0b207a..9b7b7139f4 100644
--- a/activejob/lib/active_job/queue_adapters/test_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/test_adapter.rb
@@ -10,52 +10,50 @@ module ActiveJob
     #
     #   Rails.application.config.active_job.queue_adapter = :test
     class TestAdapter
-      class << self
-        attr_accessor(:perform_enqueued_jobs, :perform_enqueued_at_jobs, :filter)
-        attr_writer(:enqueued_jobs, :performed_jobs)
+      attr_accessor(:perform_enqueued_jobs, :perform_enqueued_at_jobs, :filter)
+      attr_writer(:enqueued_jobs, :performed_jobs)
 
-        # Provides a store of all the enqueued jobs with the TestAdapter so you can check them.
-        def enqueued_jobs
-          @enqueued_jobs ||= []
-        end
+      # Provides a store of all the enqueued jobs with the TestAdapter so you can check them.
+      def enqueued_jobs
+        @enqueued_jobs ||= []
+      end
 
-        # Provides a store of all the performed jobs with the TestAdapter so you can check them.
-        def performed_jobs
-          @performed_jobs ||= []
-        end
+      # Provides a store of all the performed jobs with the TestAdapter so you can check them.
+      def performed_jobs
+        @performed_jobs ||= []
+      end
 
-        def enqueue(job) #:nodoc:
-          return if filtered?(job)
+      def enqueue(job) #:nodoc:
+        return if filtered?(job)
 
-          job_data = job_to_hash(job)
-          enqueue_or_perform(perform_enqueued_jobs, job, job_data)
-        end
+        job_data = job_to_hash(job)
+        enqueue_or_perform(perform_enqueued_jobs, job, job_data)
+      end
 
-        def enqueue_at(job, timestamp) #:nodoc:
-          return if filtered?(job)
+      def enqueue_at(job, timestamp) #:nodoc:
+        return if filtered?(job)
 
-          job_data = job_to_hash(job, at: timestamp)
-          enqueue_or_perform(perform_enqueued_at_jobs, job, job_data)
-        end
+        job_data = job_to_hash(job, at: timestamp)
+        enqueue_or_perform(perform_enqueued_at_jobs, job, job_data)
+      end
 
-        private
+      private
 
-        def job_to_hash(job, extras = {})
-          { job: job.class, args: job.serialize.fetch('arguments'), queue: job.queue_name }.merge!(extras)
-        end
+      def job_to_hash(job, extras = {})
+        { job: job.class, args: job.serialize.fetch('arguments'), queue: job.queue_name }.merge!(extras)
+      end
 
-        def enqueue_or_perform(perform, job, job_data)
-          if perform
-            performed_jobs << job_data
-            Base.execute job.serialize
-          else
-            enqueued_jobs << job_data
-          end
+      def enqueue_or_perform(perform, job, job_data)
+        if perform
+          performed_jobs << job_data
+          Base.execute job.serialize
+        else
+          enqueued_jobs << job_data
         end
+      end
 
-        def filtered?(job)
-          filter && !Array(filter).include?(job.class)
-        end
+      def filtered?(job)
+        filter && !Array(filter).include?(job.class)
       end
     end
   end
diff --git a/activejob/lib/active_job/test_helper.rb b/activejob/lib/active_job/test_helper.rb
index bb8b267c31..5e309c1dca 100644
--- a/activejob/lib/active_job/test_helper.rb
+++ b/activejob/lib/active_job/test_helper.rb
@@ -11,9 +11,6 @@ module ActiveJob
         ActiveJob::Base.queue_adapter = :test
         clear_enqueued_jobs
         clear_performed_jobs
-        queue_adapter.perform_enqueued_jobs = false
-        queue_adapter.perform_enqueued_at_jobs = false
-        queue_adapter.filter = nil
         super
       end
 
diff --git a/activejob/test/cases/adapter_test.rb b/activejob/test/cases/adapter_test.rb
index f0c710f9ed..6d75ae9a7c 100644
--- a/activejob/test/cases/adapter_test.rb
+++ b/activejob/test/cases/adapter_test.rb
@@ -2,6 +2,6 @@ require 'helper'
 
 class AdapterTest < ActiveSupport::TestCase
   test "should load #{ENV['AJ_ADAPTER']} adapter" do
-    assert_equal "active_job/queue_adapters/#{ENV['AJ_ADAPTER']}_adapter".classify, ActiveJob::Base.queue_adapter.name
+    assert_equal "active_job/queue_adapters/#{ENV['AJ_ADAPTER']}_adapter".classify, ActiveJob::Base.queue_adapter.class.name
   end
 end
diff --git a/activejob/test/cases/queue_adapter_test.rb b/activejob/test/cases/queue_adapter_test.rb
new file mode 100644
index 0000000000..d801a0852c
--- /dev/null
+++ b/activejob/test/cases/queue_adapter_test.rb
@@ -0,0 +1,24 @@
+require 'helper'
+
+class QueueAdapterTest < ActiveJob::TestCase
+  test 'should forbid nonsense arguments' do
+    assert_raises(ArgumentError) { ActiveJob::Base.queue_adapter = Mutex }
+    assert_raises(ArgumentError) { ActiveJob::Base.queue_adapter = Mutex.new }
+  end
+
+  test 'should warn on passing an adapter class' do
+    klass = Class.new do
+      def self.name
+        'fake'
+      end
+
+      def enqueue(*)
+      end
+
+      def enqueue_at(*)
+      end
+    end
+
+    assert_deprecated { ActiveJob::Base.queue_adapter = klass }
+  end
+end
diff --git a/activejob/test/cases/test_case_test.rb b/activejob/test/cases/test_case_test.rb
index 7d1702990e..bd23878b23 100644
--- a/activejob/test/cases/test_case_test.rb
+++ b/activejob/test/cases/test_case_test.rb
@@ -9,6 +9,6 @@ class ActiveJobTestCaseTest < ActiveJob::TestCase
   end
 
   def test_set_test_adapter
-    assert_equal ActiveJob::QueueAdapters::TestAdapter, self.queue_adapter
+    assert_kind_of ActiveJob::QueueAdapters::TestAdapter, self.queue_adapter
   end
 end
diff --git a/activejob/test/support/integration/test_case_helpers.rb b/activejob/test/support/integration/test_case_helpers.rb
index ee2f6aebea..fe075cf7c7 100644
--- a/activejob/test/support/integration/test_case_helpers.rb
+++ b/activejob/test/support/integration/test_case_helpers.rb
@@ -27,8 +27,8 @@ module TestCaseHelpers
       jobs_manager.clear_jobs
     end
 
-    def adapter_is?(adapter)
-      ActiveJob::Base.queue_adapter.name.split("::").last.gsub(/Adapter$/, '').underscore==adapter.to_s
+    def adapter_is?(adapter_class_symbol)
+      ActiveJob::Base.queue_adapter.class.name.split("::").last.gsub(/Adapter$/, '').underscore == adapter_class_symbol.to_s
     end
 
     def wait_for_jobs_to_finish_for(seconds=60)