준비

$ gem install slack-ruby-client

gem 'slack-ruby-client'

소스 코드

require 'slack-ruby-client'

Slack.configure do |config|
  # APIトークンを設定
  config.token = 'xoxp-xxxxxxxxxxxx-xxxxxxxxxxxx-xxxxxxxxxxxx-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'
end

# APIクライアントを生成
client = Slack::Web::Client.new

# #チャンネル名 of @ユーザー名
channel = '#slack-test'

# メッセージ
text = 'Hello World'

response = client.chat_postMessage(channel: channel, text: text, as_user: false)

pp response

$ ruby slack.rb
{"ok"=>true,
...

참고