Add types for actionmailbox v8.1

gems/actioncable/README.md

@@ -13,6 +13,7 @@ If you have any questions, please contact the maintainers. Refer to `_reviewers.
 ## Target gems
 
 - actioncable
+- actionmailbox
 - actionmailer
 - actionpack
 - actiontext

gems/actionmailbox/.rubocop.yml

@@ -0,0 +1,8 @@
+inherit_from: ../../.rubocop.yml
+
+RBS/Layout:
+  Enabled: true
+RBS/Lint:
+  Enabled: true
+RBS/Style:
+  Enabled: true

gems/actionmailbox/8.1/_test/test.rb

@@ -0,0 +1,42 @@
+# Write Ruby code to test the RBS.
+# It is type checked by `steep check` command.
+
+require "actionmailbox"
+
+class ForwardsMailbox < ActionMailbox::Base
+  before_processing :require_sender
+
+  def process
+    mail.subject
+    inbound_email.message_id.size
+    bounced! unless inbound_email.processed?
+  end
+
+  private
+
+  def require_sender
+  end
+end
+
+class ApplicationMailbox < ActionMailbox::Base
+  routing all: :forwards
+end
+
+inbound_email = ActionMailbox::InboundEmail.new
+inbound_email.status.to_sym
+inbound_email.message_id.size
+inbound_email.message_checksum.size
+inbound_email.created_at.to_date
+inbound_email.raw_email.attached?
+inbound_email.delivered! unless inbound_email.bounced? || inbound_email.failed?
+inbound_email.processing! if inbound_email.pending?
+inbound_email.mail.subject
+inbound_email.source.size
+inbound_email.processed? || ForwardsMailbox.receive(inbound_email)
+
+class ForwardsMailboxTest < ActionMailbox::TestCase
+  def test_receive
+    receive_inbound_email_from_mail(to: "save@example.com", subject: "Hello")
+    create_inbound_email_from_mail(to: "save@example.com")
+  end
+end

gems/actionmailbox/8.1/_test/test.rbs

@@ -0,0 +1,14 @@
+class ForwardsMailbox < ActionMailbox::Base
+  def process: () -> void
+
+  private
+
+  def require_sender: () -> void
+end
+
+class ApplicationMailbox < ActionMailbox::Base
+end
+
+class ForwardsMailboxTest < ActionMailbox::TestCase
+  def test_receive: () -> void
+end