added min required subscribed fields for messenger bot

lib/rubotnik.rb

@@ -25,12 +25,12 @@ class << self
 
     def logger
       @logger ||= Logger.new($stdout).tap do |log|
-        log.progname = self.name
+        log.progname = name
       end
     end
 
     def route(event, &block)
-      if [:message, :postback].include?(event)
+      if %i[message postback].include?(event)
         Bot.on event do |e|
           case e
           when Facebook::Messenger::Incoming::Message
@@ -45,7 +45,10 @@ def route(event, &block)
     end
 
     def subscribe(token)
-      Facebook::Messenger::Subscriptions.subscribe(access_token: token)
+      Facebook::Messenger::Subscriptions.subscribe(
+        access_token: token,
+        subscribed_fields: %w[messages messaging_postbacks]
+      )
     end
 
     def set_profile(*payloads)

spec/rubotnik_spec.rb

@@ -20,9 +20,13 @@
 
   describe 'subscribe' do
     it 'subscribes to a fb page' do
+      subscribed_fields = %w[messages messaging_postbacks]
       token = 'xxx'
       expect(Facebook::Messenger::Subscriptions)
-        .to receive(:subscribe).with(access_token: token)
+        .to receive(:subscribe).with(
+          access_token: token,
+          subscribed_fields: subscribed_fields
+        )
 
       described_class.subscribe(token)
     end