Setting display resolution for Selenium tests on virtual machine as Jenkins Slave - selenium

Question

I'm having trouble running some Selenium tests on a Jenkins Slave. To be specific, the display resolution that is used to run the tests is too small, causing some of the tests to fail.
To check the display resolution, we log the display height and width to the console, using:
driver.manage().window().maximize();
System.out.println("Window height: " + driver.manage().window().getSize().getHeight());
System.out.println("Window width: " + driver.manage().window().getSize().getWidth());
This returns:
Window height: 784
Window width: 1040
which seems like a very strange resolution to me. The desired resolution is 1920 x 1080.
The server that is used as a slave is a virtual machine (Windows Server 2012 R2). The Jenkins Slave is Connected via JNLP agent. The slave has the service running with Log On As "Local System" with the "Allow service to interact with desktop" option enabled.
So far we've tried a number of things like:
Connecting to slave VM using RDP and disconnecting to leave session open with desired display resolution
Using powershell to set the display resolution
Setting the default display resolution in the VM configuration
Setting the window dimensions using Selenium
And more...
All of these didn't resolve the issues. Suggestions are very welcome!

Answer 1

Finally managed to fix these issues after realizing that Jenkins does not necessarily need to run the slaves as a windows service. To start the slave, the JNLP agent can be downloaded from Jenkins and copied to the server. When running the JNLP file, you can select for the option to install the slave agent as a service.
Previously we had this option selected, that's why the slave was running as a service. After stopping and removing the service, we ran the JNLP file again and made sure to not select the option.
The solutions suggested that included disconnecting the remote desktop session and leaving the session open with a large resolution didn't work when running the slave as a service. They do work however when running the slave in the default way.
Make sure that the remote desktop session is not ended after a certain period of time:
Hope this helps someone!

Answer 2

Based on my experience with this you can't solve this problem programmatically. Your tests will run on the resolution which was used last time when you physically accessed this VM's display. For example, if I open VM on my big screen monitor and maximize it, tests will run on that resolution. But if I open it on my laptop screen and close RDP connection, tests will run on that smaller screen size.
I know it sounds strange, but I really couldn't find better solution. :D So now I must be careful to maximize VM display on my bigger screen before I close VM. You will probably dislike this answer, but remember it when you find yourself out of other solutions. ;)

Answer 3

Solution that worked for me is to run Chrome in a 'headless' mode (without GUI). It works with Jenkins Agent running as a service, when GUI is not available.
Here is the code sample of the web driver initialization:
var options = new ChromeOptions();
options.BinaryLocation = #"C:\Program Files\Google\Chrome\Application\chrome.exe";
options.AddArgument("Headless");
options.AddArgument("window-size=1920,1080");
driver = new ChromeDriver(#"<path>\Selenium.WebDriver.ChromeDriver.2.37.0\driver\win32", options);

Answer 4

I've been experienced the same issue. My seleniumn tests run under jenkins slave installed as windows service, using "Local System" account with "Allow service to interact with desktop" option enabled in windows 7. Some test cases were always failed due to incorrect display resolution.
I logged in to the console of the windows VM (EXSI Server + VMware Fusion), changed the resolution to 1400x900, and restart the windwos VM. Everything works well now.