Consider passing RoborazziOptions to Compose Preview Support

[takahirom]

My suggestion is to create a roborazziOptions(): RoborazziOptions function in the tester interface to set up the RoborazziOptions. However, we might want to access the annotations of the Preview function within roborazziOptions(). We could pass a ComposablePreview instance as a parameter, but I'm unsure if there's a more efficient approach.

[sergio-sastre]

This would be for default options right?
For options applying to a single Preview, I’d bet the best is to provide a @ RoborazziConfig annotation with params matching the options -and annotate your @ Previews with it.

then you can get that info via

AndroidComposablePreviewScanner()
  …
  .includeAnnotationInfoForAllOf(RoborazziConfig::class.java)

and map them in the tests with
ComposablePreview<AndroidPreview>.getAnnotation<RoborazziConfig>()

You can find some examples here:

https://github.com/sergio-sastre/Android-screenshot-testing-playground/tree/master/lazycolumnscreen-previews/roborazzi/src

[takahirom]

Thanks! I believe we have two main use cases for this:

1. Users can set up tests using @RoborazziConfig. We should add @RoborazziConfig to allow users to configure tests using a prepared annotation, as you suggested.

(In Roborazzi)
annotation class RoborazziConfig(xxxx)

class AndroidComposePreviewTester : ComposePreviewTester<AndroidPreviewInfo> {
  // This will be a new method of ComposePreviewTester
  override fun roborazziOptions(): RoborazziOptions {
     // How to access the composablePreview here?
     // options().composablePreview or passing as a parameter
     val someOptions = composablePreview.getAnnotation<RoborazziConfig>().xxxx
     return RoborazziOptions(xxx)
  }

  override fun test(composablePreview) {
      val roborazziOptions = roborazziOptions()
...
  }
}

https://github.com/takahirom/roborazzi/blob/main/roborazzi-compose-preview-scanner-support/src/main/java/com/github/takahirom/roborazzi/RoborazziPreviewScannerSupport.kt#L85C1-L85C34 (The current implementation of AndroidComposePreviewTester)

2. Users want to set the default diff tolerance or their custom annotations

(In user project)
class MyCustomComposePreviewTester : ComposePreviewTester<AndroidPreviewInfo> by AndroidComposePreviewTester() {
  override fun roborazziOptions(): RoborazziOptions {
     // How to access the composablePreview here?
     // options().composablePreview or passing as a parameter
     val someOptions = composablePreview.getAnnotation<UserCustomConfig>().xxxx
     return RoborazziOptions(xxx)
  }
}

I think we need to consider adding a new roborazziOptions() method to the tester interface and determine how we can pass composablePreview to roborazziOptions(), or explore other approaches.

[sergio-sastre]

So for me there are 3 use cases then:

1. Default Roborazzi options, set in the plugin
2. Per test Roborazzi Options set via a @RoborazziConfig provided by Roborazzi
3. Per test Roborazzi Options set via a custom annotation

I'd focus first on providing options 1 & 2
3rd is definitely harder to maintain and for more advanced users. I'd rather add it later, if ever.