When I run this test I get:
Unexpected exception of type [JSONDecoderException] with message [Cannot decode an empty string] in [/Users/gina/Sites/thinkup/webapp/_lib/class.JSONDecoder.php line 37]
	in testParseJSONErrorCodeAPI
	in TestOfTwitterAPIAccessorOAuth

And I think that's because this error_source_user.json wasn't included with this pull request, because it doesn't exist in my test data folder.