Golden tests, also called screenshot tests, let's you write tests to easily find UI regressions. It compares the UI to saved golden screenshots, and if there is a pixel difference the tests will fail. It gives us confidence that code changes does not cause UI regressions.

Updating goldens

An expected change to the UI will also cause the golden tests to fail. If this is unintended, you will need to change your code to prevent the UI change. If it was intended, you will then need to update the goldens by running the following command on your machine:

flutter test --update-goldens

Due to slight differences in rendering across platforms, mostly around text, the tests will only be run on a Linux machine on Github Actions (because it's cheaper). This means that if you update the tests on a macOS or Windows machine the golden tests will not pass on Github Actions. Instead you are recommended to download the goldens directly from the failed Github Actions job, and use those inside of your branch.

You can find the goldens under Artifacts in the top menu inside of the failed Github Actions job. It will include the master image, your test image and the difference.

Shadows in golden tests

In the golden tests the shadows are opaqued, to reduce the likelihood of golden file tests being flaky. A side effect of this is that we are not testing the exact rendering of shadows inside of the goldens.