Configuring Windows Service for Optimal Screen Resolution in Automated UI Testing

Configuring Windows Service for Optimal Screen Resolution in Automated UI Testing

11 April 2024 Stephan Petzl Leave a comment Tech-Help

When managing automated UI tests in a continuous integration setup, such as one utilizing Jenkins with Selenium Grid, it’s crucial to ensure that the screen resolution meets the requirements of the tests. A common issue that arises is that the default resolution for Windows Services interacting with the desktop may not align with what is needed for accurate test results. In this guide, we’ll explore a practical solution to adjust the screen resolution for automated UI tests running on Windows services.

Understanding the Challenge

In a typical setup where Jenkins controls Windows Slaves as a service, services are defined to interact with the desktop. However, this can lead to a scenario where the UI tests execute at a lower resolution than desired. For instance, tests may run at 1036 x 780 pixels, but a higher resolution such as 1600 x 1200 pixels is required for certain applications.

Practical Solution: VNC Service

A practical workaround to this resolution issue is the use of a VNC (Virtual Network Computing) service. This approach involves the following steps:

  • Install a VNC service on all the nodes that will be running the UI tests.
  • Write a script that adjusts the desktop resolution before initiating any tests.

By integrating a VNC service into your testing nodes, you can control and set the desktop resolution to a higher value, such as 1280 x 1024 pixels. Although this may not reach the desired 1600 x 1200 pixels, it has proven to be a sufficient solution for many automated testing scenarios, including both Selenium and GUI automation tests.

Alternative Consideration: Foregoing Windows Service

If the resolution provided by the VNC service is not satisfactory, there is an alternative method, albeit with its own set of trade-offs. One can run Jenkins not as a Windows Service but rather through an open Remote Desktop Connection (RDC) that manages the Jenkins JNLP process. While this approach can potentially offer a higher resolution, it requires maintaining an open RDC session, which may not be optimal for all use cases.


Choosing the right solution for screen resolution issues when running automated UI tests on Windows services will depend on the specific requirements and constraints of your setup. The VNC service method provides a balance between resolution improvement and ease of maintenance, making it a viable option for many testing environments. For those who require higher resolutions and can manage the demands of an open RDC session, running Jenkins through JNLP may be the preferred route. Consider your testing needs and infrastructure capabilities to make an informed decision.

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