Drive's Ruby API - Things I've learned using the googl-api-ruby-client 0.9 -

drive_api_ruby_examples.rb

#Authentification
#Notice the authorization.refresh!. 
def get_drive_service(user)
  authorization = Signet::OAuth2::Client.new(
      :client_id => 'example',
      :client_secret => 'example',
      access_token: user.access_token, 
      refresh_token: user.refresh_token, 
      token_credential_uri: 'https://www.googleapis.com/oauth2/v3/token')
  drive_service = Google::Apis::DriveV3::DriveService.new
  authorization.refresh!
  drive_service.authorization = authorization
  return drive_service
end
  
#Deleting a file
#Moving a file to the trash, passing only one parameter
file_metadata = {trashed: true}
new_file = drive_service.update_file(file.gdrive_id,file_metadata,{})

#Creating a notification channel
drive_service = get_drive_service(user)
page_token = user_get_drive_changes_page_token(user);
uuid = SecureRandom.uuid
channel = Google::Apis::DriveV3::Channel.new(id: uuid, type:'web_hook', address:'https://example.com/notifications')
result = drive_service.watch_change(page_token,channel)

Thanks for posting this - Google picked it up and it would have taken me a long time to figure out how to watch_change without it.