The Screenshot Comparison browser is where all your screenshot comparisons will populate, and as you introduce new ones or if a screenshot comparison fails, this view is where you'll take care
of it. From this browser, you can review the failures and make the correct decision, which might be to update the screenshot if a feature change has necessitated the updated screenshot or enter a
bug report for your game if you suspect there is an issue.
To access the Screenshot Comparison browser, you'll first need to open Unreal (Session) Frontend. You can do this from inside the Editor by selecting Window > Developer Tools > Session Frontend.
The Screenshot Comparison Browser from Epic's internal test project for Automation Testing.
When screenshots are captured they will be saved to the project's folder in the Saved > Automation > Comparisons folder. You can use the text box to enter your save location
When several tests have been run, you'll have your own populated images for comparison. This will give you access to several options for what to do with these images when connected to Source Control.
If you're not connected to any form of source control, these dialog options will be disabled.
Replace/Add As Alternative
Adds the screenshot to the ground truth folder and adds it to a pending change list in your Source Control.
Deletes all examples of ground truth data and replaces them with the newest screenshot as the new ground truth data.
Add As Alternative
Occasionally, two images can both be correct. Perhaps due to small differences in hardware or driver or maybe even extensions the hardware supports. Because we only bucket screenshots based on Platform_RHI_ShaderModel, it's possible further refinement is needed. That's where Add As Alternative comes into play. It adds another ground truth version of the image, and when comparing images, the system will always pick the ground truth screenshot matching closest based on the metadata. This option will be grayed out if the screenshot is from an identical device.
Always use Delete All Reports before running a fresh set of tests. Because the tool accumulates individual reports over time, there's no good place for the tool to automatically clean up
reports from a previous run in the applications. This ensures that you start with a clean slate before running the next tests.