Qualified night/dark assets not being picked up in @Preview snapshot tests

[drinkthestars]

Given the following:

@Preview(name = "TestBox - Light")
@Composable
fun TestPreviewLight() {
    TestBox()
}

@Preview(name = "TestBox - Dark", uiMode = Configuration.UI_MODE_NIGHT_YES)
@Composable
fun TestPreviewDark() {
    TestBox()
}

@Composable
fun TestBox(
    modifier: Modifier = Modifier
) {
    Box(
        modifier = modifier.size(100.dp)
    ) {
        Image(
            imageVector = ImageVector.vectorResource(id = R.drawable.test_drawable),
            contentDescription = "Testing background",
        )
    }
}

where the R.drawable.test_drawable is a vector that references night/day qualified colors or has a drawable-night equivalent, the recorded snapshots only show the light variant - somehow the dark/night qualified assets are not being picked up:

Preview:

Golden Snapshots:

Tried the following to try to force it, but didn't work either:

@Preview...
fun TestPreview() {
    val customConfiguration = Configuration(LocalConfiguration.current).apply {
        uiMode = Configuration.UI_MODE_NIGHT_YES
    }
    CompositionLocalProvider(LocalConfiguration provides customConfiguration) {
        TestBox()
    }
}

Is this a bug/limitation or is it a config issue? Thanks!

[vinaygaba]

@drinkthestars Showkase isn't currently parsing uiMode from the @Preview annotation but should be possible to add. The open question from my perspective is that each component anyway gets previewed in dark mode inside the Showkase browser and I wonder if that should be the behavior even with the Paparazzi screenshots? If that is indeed the case, I'm on the fence about how that's reconciled with previews that are specifically meant to be in dark mode through the use of the uiMode property. Any thoughts?

[drinkthestars]

Continuing an offline discussion. Gave it some more thought, and this is probably a very naive approach but it looks like with this issue and #292, we have the following requirements:

• Allow @Preview args such as uiMode to be respected.
• Allow developers to specify which UI permutations are important for their projects (e.g., Dark Mode, Font Scaling, RTL).
• Maintain default behavior when no custom configuration is specified - so, enable explicit customization through an opt-in mechanism...

For the opt-in mechanism:
Introduce a new annotation, e.g. ShowkaseCustomConfig, which can be used in conjunction with @Preview. This annotation supports hierarchical configuration options to specify how permutations should be handled.

The following cases would be supported:

Case 1:
Merely inheriting from @Preview - this mode guarantees that the @Preview settings are used as is.

@Preview(uiMode = Configuration.UI_MODE_NIGHT_YES)
@ShowkaseCustomConfig(config = ShowkaseCustomConfig.Config.InheritPreview)
@Composable
fun NightPreview() {
    // This Composable will strictly follow the NIGHT mode setup from @Preview, no additional permutations.
}

Case 2:
In this scenario, specific dimensions are included or excluded, building on the base settings from @Preview.

@Preview(uiMode = Configuration.UI_MODE_NIGHT_YES)
@ShowkaseCustomConfig(config = ShowkaseCustomConfig.Config.MergePreview(
    excludeDimensions = arrayOf(Dimension.RTL)
))
@Composable
fun CustomizedPreview() {
    // Applies NIGHT mode from @Preview; includes everything except RTL.
}

Case 3:
This setup specifies broad customization, impacting how permutations are generated without specific @Preview settings to override.

@Preview
@ShowkaseCustomConfig(config = ShowkaseCustomConfig.Config.MergePreview(
    excludeDimensions = arrayOf(Dimension.RTL, Dimension.FontSize)
))
@Composable
fun BroadCustomizedPreview() {
    // Generates permutations for all UI modes but excludes RTL & FontSize.
}

Handling Complex Edge Cases
One example: if no @Preview args are provided but MergePreview is used, the default UI settings should be assumed, and only the specified excludeDimensions should be applied.

This assumes a lot of flexibility is required - if we assume some flexibility loss perhaps this can be whittled down further. Overall the main idea is to have some type of an opt-in customization mechanism. Sorry for the long text, hoping this makes sense somewhat 😅

[vinaygaba]

@drinkthestars For the Showkase configuration, do you think it makes sense to handle it at the root level instead of doing it for each preview? Would that work better?

[drinkthestars]

@vinaygaba hmm, maybe 🤔 would you have an example of what you're thinking of? trying to visualize it