Make AJ::Base#enqueue return false if the job wasn't enqueued

activejob/lib/active_job/callbacks.rb

@@ -29,6 +29,9 @@ module ActiveJob
     included do
       define_callbacks :perform
       define_callbacks :enqueue
+
+      class_attribute :return_false_on_aborted_enqueue, instance_accessor: false, instance_predicate: false
+      self.return_false_on_aborted_enqueue = false
     end
 
     # These methods will be included into any Active Job object, adding

activejob/lib/active_job/enqueuing.rb

@@ -46,14 +46,25 @@ module ActiveJob
       self.scheduled_at = options[:wait_until].to_f if options[:wait_until]
       self.queue_name   = self.class.queue_name_from_part(options[:queue]) if options[:queue]
       self.priority     = options[:priority].to_i if options[:priority]
+      successfully_enqueued = false
       run_callbacks :enqueue do
         if scheduled_at
           self.class.queue_adapter.enqueue_at self, scheduled_at
         else
           self.class.queue_adapter.enqueue self
         end
+        successfully_enqueued = true
+      end
+      if successfully_enqueued
+        self
+      else
+        if self.class.return_false_on_aborted_enqueue
+          false
+        else
+          ActiveSupport::Deprecation.warn "this will return false, set config.active_job.return_false_on_aborted_enqueue = true to remove deprecation."
+          self
+        end
       end
-      self
     end
   end
 end

activejob/test/cases/callbacks_test.rb

@@ -2,6 +2,7 @@
 
 require "helper"
 require "jobs/callback_job"
+require "jobs/abort_before_enqueue_job"
 
 require "active_support/core_ext/object/inclusion"
 
@@ -22,4 +23,32 @@ class CallbacksTest < ActiveSupport::TestCase
     assert "CallbackJob ran around_enqueue_start".in? enqueued_callback_job.history
     assert "CallbackJob ran around_enqueue_stop".in? enqueued_callback_job.history
   end
+
+  test "#enqueue returns false when before_enqueue aborts callback chain and return_false_on_aborted_enqueue = true" do
+    begin
+      prev = ActiveJob::Base.return_false_on_aborted_enqueue
+      ActiveJob::Base.return_false_on_aborted_enqueue = true
+      assert_equal false, AbortBeforeEnqueueJob.new.enqueue
+    ensure
+      ActiveJob::Base.return_false_on_aborted_enqueue = prev
+    end
+  end
+
+  test "#enqueue returns self when before_enqueue aborts callback chain and return_false_on_aborted_enqueue = false" do
+    begin
+      prev = ActiveJob::Base.return_false_on_aborted_enqueue
+      ActiveJob::Base.return_false_on_aborted_enqueue = false
+      job = AbortBeforeEnqueueJob.new
+      assert_deprecated do
+        assert_equal job, job.enqueue
+      end
+    ensure
+      ActiveJob::Base.return_false_on_aborted_enqueue = prev
+    end
+  end
+
+  test "#enqueue returns self when the job was enqueued" do
+    job = CallbackJob.new
+    assert_equal job, job.enqueue
+  end
 end

activejob/test/jobs/abort_before_enqueue_job.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class AbortBeforeEnqueueJob < ActiveJob::Base
+  before_enqueue { throw(:abort) }
+
+  def perform
+    raise "This should never be called"
+  end
+end

railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults_6_0.rb.tt

@@ -15,3 +15,6 @@
 # This option is not backwards compatible with earlier Rails versions.
 # It's best enabled when your entire app is migrated and stable on 6.0.
 # Rails.application.config.action_dispatch.use_cookies_with_metadata = true
+
+# Return false instead of self when #enqueue method was aborted from the callback
+Rails.application.config.active_job.return_false_on_aborted_enqueue = true