Add twurl version to user agent header (#126)

* Add twurl version to user agent header

* Add test

Author: smaeda-ks

lib/twurl/oauth_client.rb

@@ -124,9 +124,15 @@ def perform_request_from_options(options, &block)
       end
 
       request.oauth!(consumer.http, consumer, access_token)
+      request['user-agent'] = user_agent
       consumer.http.request(request, &block)
     end
 
+    def user_agent
+      "twurl version: #{Version} " \
+      "platform: #{RUBY_ENGINE} #{RUBY_VERSION} (#{RUBY_PLATFORM})"
+    end
+
     def exchange_credentials_for_access_token
       response = begin
         consumer.token_request(:post, consumer.access_token_path, nil, {}, client_auth_parameters)

test/oauth_client_test.rb

@@ -167,6 +167,20 @@ def test_content_type_is_set_to_form_encoded_if_not_set_and_data_in_options
 
     client.perform_request_from_options(options)
   end
+
+  def test_user_agent_request_header_is_set
+    client = Twurl::OAuthClient.test_exemplar
+    expected_ua_string = "twurl version: #{Twurl::Version} platform: #{RUBY_ENGINE} #{RUBY_VERSION} (#{RUBY_PLATFORM})"
+
+    mock(client.consumer.http).request(
+      satisfy { |req|
+        req.is_a?(Net::HTTP::Get) &&
+        req['user-agent'] == expected_ua_string
+      }
+    )
+
+    client.perform_request_from_options(options)
+  end
 end
 
 class Twurl::OAuthClient::CredentialsForAccessTokenExchangeTest < Twurl::OAuthClient::AbstractOAuthClientTest