Fix ActionMailer assertion not working for mail defining delivery_job:

- If a Mail defines a custom delivery_job, all ActionMailer assertion
  helper (assert_emails, assert_enqueued_emails ...) wouldn't work.

  ```ruby
    MyMailer < ApplicationMailer
      self.delivery_job = MyJob
    end

    # This assertion will fail
    assert_emails(1) do
      MyMailer.my_mail.deliver_later
    end

  This PR leverage the new ActiveJob feature that accepts Procs for the
  `only` keyword and check if the delivery job is one of ActionMailer
   registered ones.

1 files changed, 51 insertions, 0 deletions

diff --git a/actionmailer/test/test_helper_test.rb b/actionmailer/test/test_helper_test.rb
index d31170706b..c700db9408 100644
--- a/actionmailer/test/test_helper_test.rb
+++ b/actionmailer/test/test_helper_test.rb
@@ -24,6 +24,17 @@ class TestHelperMailer < ActionMailer::Base
   end
 end
 
+class CustomDeliveryJob < ActionMailer::DeliveryJob
+end
+
+class CustomParameterizedDeliveryJob < ActionMailer::Parameterized::DeliveryJob
+end
+
+class CustomDeliveryMailer < TestHelperMailer
+  self.delivery_job = CustomDeliveryJob
+  self.parameterized_delivery_job = CustomParameterizedDeliveryJob
+end
+
 class TestHelperMailerTest < ActionMailer::TestCase
   include ActiveSupport::Testing::Stream
 
@@ -69,6 +80,26 @@ class TestHelperMailerTest < ActionMailer::TestCase
     end
   end
 
+  def test_assert_emails_with_custom_delivery_job
+    assert_nothing_raised do
+      assert_emails(1) do
+        silence_stream($stdout) do
+          CustomDeliveryMailer.test.deliver_later
+        end
+      end
+    end
+  end
+
+  def test_assert_emails_with_custom_parameterized_delivery_job
+    assert_nothing_raised do
+      assert_emails(1) do
+        silence_stream($stdout) do
+          CustomDeliveryMailer.with(foo: "bar").test_parameter_args.deliver_later
+        end
+      end
+    end
+  end
+
   def test_assert_emails_with_enqueued_emails
     assert_nothing_raised do
       assert_emails 1 do
@@ -201,6 +232,16 @@ class TestHelperMailerTest < ActionMailer::TestCase
     assert_match(/2 .* but 1/, error.message)
   end
 
+  def test_assert_enqueued_emails_with_custom_delivery_job
+    assert_nothing_raised do
+      assert_enqueued_emails(1) do
+        silence_stream($stdout) do
+          CustomDeliveryMailer.test.deliver_later
+        end
+      end
+    end
+  end
+
   def test_assert_enqueued_emails_too_many_sent
     error = assert_raise ActiveSupport::TestCase::Assertion do
       assert_enqueued_emails 1 do
@@ -252,6 +293,16 @@ class TestHelperMailerTest < ActionMailer::TestCase
     end
   end
 
+  def test_assert_enqueued_email_with_when_mailer_has_custom_delivery_job
+    assert_nothing_raised do
+      assert_enqueued_email_with CustomDeliveryMailer, :test do
+        silence_stream($stdout) do
+          CustomDeliveryMailer.test.deliver_later
+        end
+      end
+    end
+  end
+
   def test_assert_enqueued_email_with_with_no_block
     assert_nothing_raised do
       silence_stream($stdout) do