correctly set test adapter when configure the queue adapter on a per job (#26690)

The `ActiveJob::TestHelper` replace the adapter to test adapter in
`before_setup`. It gets the target class using the `descendants`, but if
the test target job class is not loaded, will not be a replacement of
the adapter.
Therefore, instead of replacing with `before_setup`, modified to
replace when setting adapter.

Fixes #26360

activejob/CHANGELOG.md

+*   Correctly set test adapter when configure the queue adapter on a per job.
+
+    Fixes #26360.
+
+    *Yuji Yaginuma*
+
 *   Push skipped jobs to `enqueued_jobs` when using `perform_enqueued_jobs` with a `only` filter in tests
 
     *Alexander Pauly*

activejob/lib/active_job/test_helper.rb

@@ -8,16 +8,35 @@ module TestHelper
       :performed_jobs, :performed_jobs=,
       to: :queue_adapter
 
+    module TestQueueAdapter
+      extend ActiveSupport::Concern
+
+      included do
+        class_attribute :_test_adapter, instance_accessor: false, instance_predicate: false
+      end
+
+      module ClassMethods
+        def queue_adapter
+          self._test_adapter.nil? ? super : self._test_adapter
+        end
+
+        def disable_test_adapter
+          self._test_adapter = nil
+        end
+
+        def enable_test_adapter(test_adapter)
+          self._test_adapter = test_adapter
+        end
+      end
+    end
+
+    ActiveJob::Base.include(TestQueueAdapter)
+
     def before_setup # :nodoc:
       test_adapter = queue_adapter_for_test
 
-      @old_queue_adapters = (ActiveJob::Base.descendants << ActiveJob::Base).select do |klass|
-        # only override explicitly set adapters, a quirk of `class_attribute`
-        klass.singleton_class.public_instance_methods(false).include?(:_queue_adapter)
-      end.map do |klass|
-        [klass, klass.queue_adapter].tap do
-          klass.queue_adapter = test_adapter
-        end
+      queue_adapter_changed_jobs.each do |klass|
+        klass.enable_test_adapter(test_adapter)
       end
 
       clear_enqueued_jobs
@@ -27,9 +46,8 @@ def before_setup # :nodoc:
 
     def after_teardown # :nodoc:
       super
-      @old_queue_adapters.each do |(klass, adapter)|
-        klass.queue_adapter = adapter
-      end
+
+      queue_adapter_changed_jobs.each { |klass| klass.disable_test_adapter }
     end
 
     # Specifies the queue adapter to use with all active job test helpers.
@@ -358,5 +376,12 @@ def instantiate_job(payload)
         job.queue_name = payload[:queue]
         job
       end
+
+      def queue_adapter_changed_jobs
+        (ActiveJob::Base.descendants << ActiveJob::Base).select do |klass|
+          # only override explicitly set adapters, a quirk of `class_attribute`
+          klass.singleton_class.public_instance_methods(false).include?(:_queue_adapter)
+        end
+      end
   end
 end

activejob/test/cases/queue_adapter_test.rb

@@ -21,6 +21,7 @@ class QueueAdapterTest < ActiveJob::TestCase
   end
 
   test "should allow overriding the queue_adapter at the child class level without affecting the parent or its sibling" do
+    ActiveJob::Base.disable_test_adapter
     base_queue_adapter = ActiveJob::Base.queue_adapter
 
     child_job_one = Class.new(ActiveJob::Base)

activejob/test/cases/test_helper_test.rb

@@ -560,3 +560,20 @@ def test_queue_adapter_is_test_adapter
     assert_instance_of ActiveJob::QueueAdapters::TestAdapter, InheritedJob.queue_adapter
   end
 end
+
+class QueueAdapterJobTest < ActiveJob::TestCase
+  def before_setup
+    @original_autoload_paths = ActiveSupport::Dependencies.autoload_paths
+    ActiveSupport::Dependencies.autoload_paths = %w(test/jobs)
+    super
+  end
+
+  def after_teardown
+    ActiveSupport::Dependencies.autoload_paths = @original_autoload_paths
+    super
+  end
+
+  def test_queue_adapter_is_test_adapter
+    assert_instance_of ActiveJob::QueueAdapters::TestAdapter, QueueAdapterJob.queue_adapter
+  end
+end

activejob/test/jobs/queue_adapter_job.rb

+class QueueAdapterJob < ActiveJob::Base
+  self.queue_adapter = :inline
+end