Methods and systems disclosed herein can be used for testing an application's rendering of output to individual controls of a Graphical User Interface (GUI), displayed on a target device executing the application. A system according to the present invention includes a test tool running on a development computer that communicates with an agent executing on the target device. Testing is performed by using the test tool to execute test scripts, which cause test input to be injected via the agent into the application on the target device. The test tool can validate whether actual output on the target device matches expected output known to the test tool. The present invention includes a variety of key components, such as a flexible trap manager for handling unexpected screens that appear during an automated test, and a configuration manger for testing against multiple languages and platform configurations.