Skip sending a message to a Slack if the payload is empty (#2)

CHANGELOG.md

@@ -5,9 +5,13 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- Fix a bug related to using a `Null` messaging
 
 ## [0.1.0] - 2021-05-26
 ### Added
 - Initial version. ([@chubchenko][])
 
 [@chubchenko]: https://github.com/chubchenko
+[Unreleased]: https://github.com/chubchenko/capistrano-slacky/compare/v0.1.0...HEAD
+[0.1.0]: https://github.com/chubchenko/capistrano-slacky/releases/tag/v0.1.0

lib/capistrano/slacky/payload.rb

@@ -11,15 +11,25 @@ def initialize(env:, action:)
         @messaging = ::Capistrano::Slacky::Messaging.for(env: env)
       end
 
+      def empty?
+        payload_for_action.nil?
+      end
+
       def to_json
         {
           username: ::Capistrano::Slacky.username,
           icon_emoji: ::Capistrano::Slacky.icon_emoji,
           channel: ::Capistrano::Slacky.channel
         }.merge(
-          @messaging.payload_for(action: @action)
+          payload_for_action
         ).to_json
       end
+
+      private
+
+      def payload_for_action
+        @payload_for_action ||= @messaging.payload_for(action: @action)
+      end
     end
   end
 end

lib/capistrano/slacky/runner.rb

@@ -11,6 +11,8 @@ def self.call(env:, action:)
           env: env, action: action
         )
 
+        return if payload.empty?
+
         ::Capistrano::Slacky::Fanout.call(payload: payload)
       end
     end