Automatic diff matching


Covered in this doc

  • What automatic diff matching is
  • Criteria for visual changes to be matched

Percy automatically matches and groups snapshots that have the same visual change, saving you time and effort while reviewing builds.


How it works

Criteria for matching diffs

For diffs to be matched, the following criteria must be met:

  • All diffs across all screenshots must have the same geometry, including size but irrespective of page coordinates.
  • Both the baseline screenshots and new screenshots must have the exact same underlying pixels across diffs.
  • Only snapshot comparisons that have the same diff geometry and underlying pixels for each enabled width and browser will be matched.

Approving and requesting changes on groups

When matching diffs are detected, they are grouped together at the top of your snapshot list. All matching changes can be approved or have changes requested with a single click. You can expand the group to inspect individual snapshots, but approve or request changes cannot be taken on individual snapshots within a group. Please note that requesting changes on a group will also automatically add a changes requested comment to each of the grouped snapshots.

If you have questions about matching diffs, please feel free to contact support.