msb-public
/
nowinandroid
mirror of https://github.com/android/nowinandroid.git
1
0
Code Issues Projects Releases Wiki Activity
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
Branches Tags
${ item.name }
Create tag ${ searchTerm }
Create branch ${ searchTerm }
from 'av/paparazzi-showkase-preview-screenshot-testing'
${ noResults }
nowinandroid/preview-screenshots
History
Alex Vanyo 332b678394
Rebase onto main 		2 years ago
..
src Rebase onto main 2 years ago
README.md Add preview screenshot testing with Paparazzi and Showkase 2 years ago
build.gradle.kts Rebase onto main 2 years ago

README.md

Preview Screenshot Tests

preview-screenshots performs automatic @Preview screenshot testing utilizing Showkase, Paparazzi and TestParameterInjector.

Showkase aggregates all @Preview definitions, and collects them into a list of components via a KSP processor. We can then use these components as parameterized inputs to tests configured with TestParameterInjector, and then we use Paparazzi to render each preview and diff the output.

This CL configures Showkase to run on all UI modules, and then aggregates them all in a test-only preview-screenshots module. These tests run all previews in a matrix of configurations:

  • Each @Preview
  • Nexus 5, Pixel 5, Pixel C
  • Font scale of 1.0 and 1.5

This could be expanded even further if desired (locale, theming, etc.)

Screenshots are rendered with layoutlib, which is the same tool that drives rendering previews in Android Studio. As a result, the screenshots being taken do not have the same fidelity as what will actually displayed on a real device. In particular, certain devices might behave slightly differently, and it isn't possible to verify display interactions with the system (dialogs, soft keyboard, etc.)

The advantage, however, is that Paparazzi runs in JVM tests, which means they are faster, and don't require managing a virtual or physical device, making it easier to parameterize across different device sizes and configurations.

Recording tests can be done with ./gradlew recordPaparazziDemoDebug, and then checked with ./gradlew verifyPaparazziDemoDebug. check is configured to depend on verifyPaparazziDemoDebug.