Expose `mailbox_for` method

Currently, the only exposed entry point into the ApplicationMailbox's configured
routing system is to call `route`, which performs a lot of work to fully
`process` inbound email. It'd be nice to have a way (e.g. in test) of checking
which mailbox an email would route to without necessarily processing it yet.

2 files changed, 19 insertions, 0 deletions

diff --git a/actionmailbox/test/unit/mailbox/routing_test.rb b/actionmailbox/test/unit/mailbox/routing_test.rb
index d4ba702ac5..1ae56eb707 100644
--- a/actionmailbox/test/unit/mailbox/routing_test.rb
+++ b/actionmailbox/test/unit/mailbox/routing_test.rb
@@ -28,4 +28,9 @@ class ActionMailbox::Base::RoutingTest < ActiveSupport::TestCase
       assert_equal "Discussion: Let's debate these attachments", $processed
     end
   end
+
+  test "mailbox_for" do
+    mail = create_inbound_email_from_fixture "welcome.eml", status: :pending
+    assert_equal RepliesMailbox, ApplicationMailbox.mailbox_for(mail)
+  end
 end
diff --git a/actionmailbox/test/unit/router_test.rb b/actionmailbox/test/unit/router_test.rb
index c5dce60856..4dd3730604 100644
--- a/actionmailbox/test/unit/router_test.rb
+++ b/actionmailbox/test/unit/router_test.rb
@@ -135,5 +135,19 @@ module ActionMailbox
         @router.add_route Array.new, to: :first
       end
     end
+
+    test "single string mailbox_for" do
+      @router.add_routes("first@example.com" => :first)
+
+      inbound_email = create_inbound_email_from_mail(to: "first@example.com", subject: "This is a reply")
+      assert_equal FirstMailbox, @router.mailbox_for(inbound_email)
+    end
+
+    test "mailbox_for with no matches" do
+      @router.add_routes("first@example.com" => :first)
+
+      inbound_email = create_inbound_email_from_mail(to: "second@example.com", subject: "This is a reply")
+      assert_nil @router.mailbox_for(inbound_email)
+    end
   end
 end