Provide the ability to override the queue adapter used by jobs under

test.

This PR adds a method called `queue_adapter_for_test` to
`ActiveJob::TestHelper`. This method is expected to provide the queue
adapter to be used for jobs under test. It maintains the current
behaviour by defaulting to an instance of
`ActiveJob::QueueAdapter::TestAdapter`. Tests that include
`ActiveJob::TestHelper` or extend from `ActiveJob::TestCase` can provide
a custom queue adapter by overriding `queue_adapter_for_test` in their
class.

2 files changed, 26 insertions, 1 deletions

diff --git a/activejob/lib/active_job/test_helper.rb b/activejob/lib/active_job/test_helper.rb
index 3feb82d432..e16af1947f 100644
--- a/activejob/lib/active_job/test_helper.rb
+++ b/activejob/lib/active_job/test_helper.rb
@@ -9,7 +9,7 @@ module ActiveJob
       to: :queue_adapter
 
     def before_setup # :nodoc:
-      test_adapter = ActiveJob::QueueAdapters::TestAdapter.new
+      test_adapter = queue_adapter_for_test
 
       @old_queue_adapters = (ActiveJob::Base.subclasses << ActiveJob::Base).select do |klass|
         # only override explicitly set adapters, a quirk of `class_attribute`
@@ -32,6 +32,19 @@ module ActiveJob
       end
     end
 
+    # Specifies the queue adapter to use with all active job test helpers.
+    #
+    # Returns an instance of the queue adapter and defaults to
+    # <tt>ActiveJob::QueueAdapters::TestAdapter</tt>.
+    #
+    # Note: The adapter provided by this method must provide some additional
+    # methods from those expected of a standard <tt>ActiveJob::QueueAdapter</tt>
+    # in order to be used with the active job test helpers. Refer to
+    # <tt>ActiveJob::QueueAdapters::TestAdapter</tt>.
+    def queue_adapter_for_test
+      ActiveJob::QueueAdapters::TestAdapter.new
+    end
+
     # Asserts that the number of enqueued jobs matches the given number.
     #
     #   def test_jobs
diff --git a/activejob/test/cases/test_helper_test.rb b/activejob/test/cases/test_helper_test.rb
index f7ee763e8a..3d863f5e65 100644
--- a/activejob/test/cases/test_helper_test.rb
+++ b/activejob/test/cases/test_helper_test.rb
@@ -509,3 +509,15 @@ class PerformedJobsTest < ActiveJob::TestCase
     assert_equal 2, ActiveJob::Base.queue_adapter.performed_jobs.count
   end
 end
+
+class OverrideQueueAdapterTest < ActiveJob::TestCase
+  class CustomQueueAdapter < ActiveJob::QueueAdapters::TestAdapter; end
+
+  def queue_adapter_for_test
+    CustomQueueAdapter.new
+  end
+
+  def test_assert_job_has_custom_queue_adapter_set
+    assert_instance_of CustomQueueAdapter, HelloJob.queue_adapter
+  end
+end