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Karate Image Comparison

This project is designed to demonstrate basic usage of the Image Comparison feature. You can also watch a video explanation here.


The Image Comparison feature was introduced in Karate 1.3.0. As a new feature with a number of options and a new UI component we wanted to provide a simple introduction to help users get started.

The included features are numbered 1 through 7 and build on each other. They are intended to demonstrate how you might start from scratch without any baseline images on a new project:

  • 1_establish_baseline.feature establishes baseline images to use in future test runs
  • 2_compare_baseline.feature compares dynamic screenshots against our baseline images
  • 3_custom_rebase.feature demonstrates the use of the onShowRebase handler to customize the filename when rebasing
  • 4_generic_rebase.feature shows a slightly more advanced use of the onShowRebase handler that incorporates image comparison configuration options
  • 5_custom_config.feature shows a complete scenario that is similar to what you might use in real tests
  • 6_outline.feature explores a more complex use case with multiple browsers
  • 7_api.feature solves some issues identified in the outline feature above using the JS API

There is also a screencast that demonstrates basic usage of the diff UI in the Karate HTML report.


The 5_custom_config.feature is a complete Karate UI test that can be executed by running ImageComparisonRunner as a JUnit test. You will be able to open the HTML report (the file-name will appear at the end of the console log) and refresh it when re-running the test.

To manually run the test execute the following commands:

  • Install maven artifacts from the latest develop branch locally
    mvn clean install -P pre-release
  • Run the test from the examples/image-comparison directory
     mvn clean test -Dtest=ImageComparisonRunner


You should be able to use the Karate extension for Visual Studio Code for stepping-through a test for troubleshooting.