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Add paparazzi and compose snapshots preview #693

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d2f10d9
Adding paparazzi and reflectively finding previews.
runningcode Dec 12, 2025
abeffbe
Add ComposePreviewScanner
runningcode Dec 15, 2025
be7ada8
Add roborazzi
runningcode Dec 15, 2025
4c3ec9d
test(android): Restore Compose test files
runningcode Dec 15, 2025
7b9cd0d
fix(android): Clean output directory before generating preview scanne…
runningcode Dec 19, 2025
29c7dda
more changes
runningcode Dec 19, 2025
d43dccf
Add ui-components
runningcode Dec 19, 2025
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3 changes: 3 additions & 0 deletions android/app/build.gradle.kts
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ plugins {
alias(libs.plugins.sentry)
alias(libs.plugins.roborazzi)
alias(libs.plugins.androidx.room)
alias(libs.plugins.paparazzi)
}

android {
Expand Down Expand Up @@ -164,6 +165,8 @@ dependencies {
ksp(libs.androidx.room.compiler)

testImplementation(libs.junit)
testImplementation(libs.reflections)
testImplementation(libs.composable.preview.scanner)
testImplementation(libs.robolectric)
testImplementation(libs.roborazzi)
testImplementation(libs.roborazzi.compose)
Expand Down
71 changes: 0 additions & 71 deletions android/app/src/test/kotlin/BookmarksScreenComposeTest.kt
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37 changes: 0 additions & 37 deletions android/app/src/test/kotlin/StoryRowComposeTest.kt
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44 changes: 44 additions & 0 deletions android/app/src/test/kotlin/com/emergetools/hackernews/ComposePreviewScanner.kt
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@@ -0,0 +1,44 @@
package com.emergetools.hackernews

import app.cash.paparazzi.Paparazzi
import org.junit.Rule
import org.junit.Test
import org.junit.runner.RunWith
import org.junit.runners.Parameterized
import sergio.sastre.composable.preview.scanner.android.AndroidComposablePreviewScanner
import sergio.sastre.composable.preview.scanner.android.AndroidPreviewInfo
import sergio.sastre.composable.preview.scanner.android.screenshotid.AndroidPreviewScreenshotIdBuilder
import sergio.sastre.composable.preview.scanner.core.preview.ComposablePreview


@RunWith(Parameterized::class)
class ComposePreviewScanner(val preview: ComposablePreview<AndroidPreviewInfo>) {

companion object {
// Optimization: This avoids scanning for every test
private val cachedPreviews: List<ComposablePreview<AndroidPreviewInfo>> by lazy {
AndroidComposablePreviewScanner()
.scanPackageTrees("com.emergetools.hackernews")
.getPreviews()
}

@JvmStatic
@Parameterized.Parameters
fun values(): List<ComposablePreview<AndroidPreviewInfo>> = cachedPreviews
}

@get:Rule val paparazzi= Paparazzi()


@Test
fun snapshotTest() {
val screenshotId = AndroidPreviewScreenshotIdBuilder(preview).build()

paparazzi.snapshot(name = screenshotId) {
val previewInfo = preview.previewInfo
preview()
}
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@sentry sentry bot Dec 15, 2025

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Bug: The previewInfo variable is extracted but unused. The preview() object is invoked directly, which likely ignores the intended preview configuration for the snapshot test.
Severity: HIGH | Confidence: High

🔍 Detailed Analysis

In the snapshot test, the previewInfo variable is extracted from the preview object but is never used. Instead, the preview() object is invoked directly. According to the library's documentation, the composable function should be invoked via the previewInfo object (e.g., previewInfo.previewComposable.invoke()). This discrepancy means that important configuration metadata from the @Preview annotation, such as device settings, locale, and theme, is likely being ignored. As a result, the generated snapshots may not reflect the intended configuration, leading to incorrect or failing tests.

💡 Suggested Fix

Replace the direct invocation preview() with the invocation from the previewInfo object, such as previewInfo.previewComposable.invoke(). This will ensure the composable is rendered with the correct configuration specified in its @Preview annotation.

🤖 Prompt for AI Agent 
Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location:
android/app/src/test/kotlin/com/emergetools/hackernews/ComposePreviewScanner.kt#L38-L40

Potential issue: In the snapshot test, the `previewInfo` variable is extracted from the
`preview` object but is never used. Instead, the `preview()` object is invoked directly.
According to the library's documentation, the composable function should be invoked via
the `previewInfo` object (e.g., `previewInfo.previewComposable.invoke()`). This
discrepancy means that important configuration metadata from the `@Preview` annotation,
such as device settings, locale, and theme, is likely being ignored. As a result, the
generated snapshots may not reflect the intended configuration, leading to incorrect or
failing tests.

Did we get this right? 👍 / 👎 to inform future reviews.
Reference ID: 7526923

}


}
4 changes: 4 additions & 0 deletions android/gradle/libs.versions.toml
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Expand Up @@ -5,6 +5,7 @@ ksp = "2.3.3"
coreKtx = "1.17.0"
junit = "4.13.2"
junitVersion = "1.1.5" # This is to match Compose's version
reflections = "0.10.2"
robolectric = "4.16"
roborazzi = "1.52.0"
espressoCore = "3.5.0" # This is to match Compose's version
Expand All @@ -31,6 +32,7 @@ uiautomator = "2.3.0"
benchmarkMacroJunit4 = "1.4.1"

[libraries]
composable-preview-scanner = { module = "io.github.sergio-sastre.ComposablePreviewScanner:android", version = "0.7.2" }
androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
androidx-lifecycle-runtime-ktx = { group = "androidx.lifecycle", name = "lifecycle-runtime-ktx", version.ref = "lifecycleRuntimeKtx" }
androidx-activity-compose = { group = "androidx.activity", name = "activity-compose", version.ref = "activityCompose" }
Expand All @@ -56,6 +58,7 @@ androidx-material3 = { group = "androidx.compose.material3", name = "material3"
extendedspans = { group = "me.saket.extendedspans", name = "extendedspans", version.ref = "extendedspans" }

okhttp = { group = "com.squareup.okhttp3", name = "okhttp", version.ref = "okhttp" }
reflections = { module = "org.reflections:reflections", version.ref = "reflections" }
retrofit = { group = "com.squareup.retrofit2", name = "retrofit", version.ref = "retrofit" }
retrofit-kotlinx-serialization = { group = "com.squareup.retrofit2", name = "converter-kotlinx-serialization", version.ref = "retrofit" }
kotlinx-serialization-json = { group = "org.jetbrains.kotlinx", name = "kotlinx-serialization-json", version.ref = "kotlinx-serialization-json" }
Expand Down Expand Up @@ -84,6 +87,7 @@ kotlin-ksp = { id = "com.google.devtools.ksp", version.ref = "ksp" }
emerge = { id = "com.emergetools.android", version.ref = "emergePlugin" }
sentry = { id = "io.sentry.android.gradle", version.ref = "sentry" }
roborazzi = { id = "io.github.takahirom.roborazzi", version.ref = "roborazzi" }
paparazzi = { id = "app.cash.paparazzi", version = "2.0.0-alpha02" }
androidx-room = { id = "androidx.room", version.ref = "room" }
android-test = { id = "com.android.test", version.ref = "agp" }

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