twitter_stream_api.rb

require 'twitter'

client = Twitter::Streaming::Client.new do |config|
  config.consumer_key = 'xxx'
  config.consumer_secret = 'xxx'
  config.access_token = 'xxx'
  config.access_token_secret = 'xxx'
end

client.filter(track: 'xxx') do |obj|
  puts obj.text if obj.is_a?(Twitter::Tweet)
end