SlackWebhook.rb

class SlackWebhook
  attr_accessor :webhook

  def initialize(webhook)
    @webhook = webhook
  end

  def send_message(text)
    uri = URI(webhook)

    connection.post do |req|
      req.url uri.path
      req.headers['Content-Type'] = 'application/json'
      req.body = { text: text }.to_json
    end
  end

  private

  def connection
    Faraday.new(url: "https://hooks.slack.com") do |faraday|
      faraday.response :json, content_type: /\bjson$/, parser_options: { symbolize_names: true }
      faraday.adapter  Faraday.default_adapter
    end
  end
end