diff --git a/Gemfile b/Gemfile
index 536a22ed..d88ba639 100644
--- a/Gemfile
+++ b/Gemfile
@@ -83,6 +83,7 @@ group :test do
   if ENV['RAILS_VERSION'].nil? || ENV['RAILS_VERSION'] >= '6.0.0'
     gem 'zeitwerk', :require => false
   end
+  gem 'concurrent-ruby'
 end
 
 group :rubocop do
diff --git a/lib/active_job/queue_adapters/delayed_job_adapter.rb b/lib/active_job/queue_adapters/delayed_job_adapter.rb
index 56626dab..6ff6d2ef 100644
--- a/lib/active_job/queue_adapters/delayed_job_adapter.rb
+++ b/lib/active_job/queue_adapters/delayed_job_adapter.rb
@@ -1,5 +1,3 @@
-require "byebug"
-
 module ActiveJob
   module QueueAdapters
     # Explicitly remove the implementation existing in older rails'.
diff --git a/spec/active_job_adapter_spec.rb b/spec/active_job_adapter_spec.rb
index 68cc4f24..fd4bb94e 100644
--- a/spec/active_job_adapter_spec.rb
+++ b/spec/active_job_adapter_spec.rb
@@ -1,20 +1,22 @@
 require 'helper'
 require 'active_job'
-require "byebug"
+require 'concurrent'
 
 describe 'a Rails active job backend' do
   module JobBuffer
+    @values = Concurrent::Array.new
+
     class << self
       def clear
-        values.clear
+        @values.clear
       end
 
       def add(value)
-        values << value
+        @values << value
       end
 
       def values
-        @values ||= []
+        @values.dup
       end
     end
   end
@@ -27,21 +29,41 @@ def perform(message)
     end
   end
 
-  let(:worker) { Delayed::Worker.new(sleep_delay: 0.5, queues: %w(integration_tests)) }
+  let(:worker) { Delayed::Worker.new(sleep_delay: 0.5, queues: %w[integration_tests]) }
 
   before do
+    JobBuffer.clear
+    Delayed::Job.delete_all
     ActiveJob::Base.queue_adapter = :delayed_job
+    ActiveJob::Base.logger = nil
   end
 
-  after do
-    JobBuffer.clear
+  it "should supply a wrapped class name to DelayedJob" do
+    TestJob.perform_later
+    job = Delayed::Job.all.last
+    expect(job.name).to match(/TestJob \[[0-9a-f-]+\] from DelayedJob\(integration_tests\) with arguments: \[\]/)
   end
 
   it 'enqueus and executes the job' do
     start_worker do
-      TestJob.perform_later('hello')
+      TestJob.perform_later('Rails')
       sleep 2
-      expect(JobBuffer.values).to eq(['hello'])
+      expect(JobBuffer.values).to eq(['Rails'])
+    end
+  end
+
+  it "should not run jobs queued on a non-listening queue" do
+    start_worker do
+      old_queue = TestJob.queue_name
+
+      begin
+        TestJob.queue_as :some_other_queue
+        TestJob.perform_later "Rails"
+        sleep 2
+        expect(JobBuffer.values.empty?).to eq true
+      ensure
+        TestJob.queue_name = old_queue
+      end
     end
   end
 
@@ -55,7 +77,7 @@ def perform(message)
 
   it 'should not run job enqueued in the future' do
     start_worker do
-      TestJob.set(wait: 5.seconds).perform_later('hello')
+      TestJob.set(wait: 5.seconds).perform_later('Rails')
       sleep 2
       expect(JobBuffer.values.empty?).to eq true
     end
@@ -63,9 +85,28 @@ def perform(message)
 
   it 'should run job enqueued in the future at the specified time' do
     start_worker do
-      TestJob.set(wait: 5.seconds).perform_later('hello')
+      TestJob.set(wait: 5.seconds).perform_later('Rails')
+      sleep 10
+      expect(JobBuffer.values).to eq(['Rails'])
+    end
+  end
+
+  it "should run job bulk enqueued in the future at the specified time" do
+    start_worker do
+      ActiveJob.perform_all_later([TestJob.new("Rails").set(wait: 5.seconds)])
+      sleep 10
+      expect(JobBuffer.values).to eq(['Rails'])
+    end
+  end
+
+  it "should run job with higher priority first" do
+    start_worker do
+      wait_until = Time.now + 3.seconds
+      TestJob.set(wait_until: wait_until, priority: 20).perform_later "1"
+      TestJob.set(wait_until: wait_until, priority: 10).perform_later "2"
       sleep 10
-      expect(JobBuffer.values).to eq(['hello'])
+
+      expect(JobBuffer.values).to eq(['2', '1'])
     end
   end