Add Mailbox and MailboxTest generators

.gitignore

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 .byebug_history
 *.sqlite3-journal
+.ruby-version
+.ruby-gemset
+/tmp/

lib/rails/generators/mailbox/USAGE

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+Description:
+============
+    Stubs out a new mailbox class in app/mailboxes and invokes your template
+    engine and test framework generators.
+
+Example:
+========
+    rails generate mailbox inbox
+
+    creates a InboxMailbox class and test:
+        Mailbox:  app/mailboxes/inbox_mailbox.rb
+        Test:     test/mailboxes/inbox_mailbox_test.rb

lib/rails/generators/mailbox/mailbox_generator.rb

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+# frozen_string_literal: true
+
+module Rails
+  module Generators
+    class MailboxGenerator < NamedBase
+      source_root File.expand_path("templates", __dir__)
+
+      argument :actions, type: :array, default: [:process], banner: "method method"
+
+      def check_class_collision
+        class_collisions "#{class_name}Mailbox", "#{class_name}MailboxTest"
+      end
+
+      def create_mailbox_file
+        template "mailbox.rb", File.join("app/mailboxes", class_path, "#{file_name}_mailbox.rb")
+
+        in_root do
+          if behavior == :invoke && !File.exist?(application_mailbox_file_name)
+            template "application_mailbox.rb", application_mailbox_file_name
+          end
+        end
+
+        template "mailer_test.rb", File.join('test/mailboxes', class_path, "#{file_name}_mailbox_test.rb")
+      end
+
+      hook_for :test_framework
+
+      private
+        def file_name # :doc:
+          @_file_name ||= super.sub(/_mailbox\z/i, "")
+        end
+
+        def application_mailbox_file_name
+          "app/mailboxes/application_mailbox.rb"
+        end
+    end
+  end
+end

lib/rails/generators/mailbox/templates/application_mailbox.rb.tt

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+# frozen_string_literal: true
+
+class ApplicationMailbox < ActionMailbox::Base
+  # routing /something/i => :somewhere
+end

lib/rails/generators/mailbox/templates/mailbox.rb.tt

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+# frozen_string_literal: true
+
+class <%= class_name %>Mailbox < ApplicationMailbox
+<% actions.each do |action| -%>
+  def <%= action %>
+  end
+<% end -%>
+end

lib/rails/generators/mailbox/templates/mailer_test.rb.tt

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+# frozen_string_literal: true
+
+require "test_helper"
+
+class <%= class_name %>MailboxTest < ActionMailbox::TestCase
+  # test "receive mail" do
+  #   receive_inbound_email_from_mail \
+  #     to: '"someone" <someone@example.com>,
+  #     from: '"else" <else@example.com>',
+  #     subject: "Hello world!",
+  #     body: "Hello?"
+  # end
+end

test/generators/mailbox_generator_test.rb

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+# frozen_string_literal: true
+require "test_helper"
+require "rails/generators/mailbox/mailbox_generator"
+
+class MailboxGeneratorTest < Rails::Generators::TestCase
+  destination File.expand_path("../../tmp", File.dirname(__FILE__))
+  setup :prepare_destination
+  tests Rails::Generators::MailboxGenerator
+
+  arguments ["inbox"]
+
+  def test_mailbox_skeleton_is_created
+    run_generator
+    assert_file "app/mailboxes/inbox_mailbox.rb" do |mailbox|
+      assert_match(/class InboxMailbox < ApplicationMailbox/, mailbox)
+      assert_match(/def process/, mailbox)
+      assert_no_match(%r{# routing /something/i => :somewhere}, mailbox)
+    end
+
+    assert_file "app/mailboxes/application_mailbox.rb" do |mailbox|
+      assert_match(/class ApplicationMailbox < ActionMailbox::Base/, mailbox)
+      assert_match(%r{# routing /something/i => :somewhere}, mailbox)
+      assert_no_match(/def process/, mailbox)
+    end
+  end
+
+  def test_check_class_collision
+    Object.send :const_set, :InboxMailbox, Class.new
+    content = capture(:stderr) { run_generator }
+    assert_match(/The name 'InboxMailbox' is either already used in your application or reserved/, content)
+  ensure
+    Object.send :remove_const, :InboxMailbox
+  end
+
+  def test_invokes_default_test_framework
+    run_generator %w(inbox foo bar)
+    assert_file "test/mailboxes/inbox_mailbox_test.rb" do |test|
+      assert_match(/class InboxMailboxTest < ActionMailbox::TestCase/, test)
+      assert_match(/# test "receive mail" do/, test)
+      assert_match(/#     to: '"someone" <someone@example.com>,/, test)
+    end
+  end
+
+  def test_check_test_class_collision
+    Object.send :const_set, :InboxMailboxTest, Class.new
+    content = capture(:stderr) { run_generator }
+    assert_match(/The name 'InboxMailboxTest' is either already used in your application or reserved/, content)
+  ensure
+    Object.send :remove_const, :InboxMailboxTest
+  end
+
+  def test_actions_are_turned_into_methods
+    run_generator %w(inbox foo bar)
+
+    assert_file "app/mailboxes/inbox_mailbox.rb" do |mailbox|
+      assert_instance_method :foo, mailbox
+      assert_instance_method :bar, mailbox
+    end
+  end
+
+  def test_mailbox_on_revoke
+    run_generator
+    run_generator ["inbox"], behavior: :revoke
+
+    assert_no_file "app/mailboxes/inbox.rb"
+  end
+
+  def test_mailbox_suffix_is_not_duplicated
+    run_generator ["inbox_mailbox"]
+
+    assert_no_file "app/mailboxes/inbox_mailbox_mailbox.rb"
+    assert_file "app/mailboxes/inbox_mailbox.rb"
+
+    assert_no_file "test/mailboxes/inbox_mailbox_mailbox_test.rb"
+    assert_file "test/mailboxes/inbox_mailbox_test.rb"
+  end
+end