Add preview test

.github/workflows/ScreenShotTest.yml

@@ -0,0 +1,55 @@
+on:
+  pull_request:
+
+jobs:
+  screenshot-test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 60
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Validate Gradle Wrapper
+        uses: gradle/wrapper-validation-action@v1
+
+      - name: Copy CI gradle.properties
+        run: mkdir -p ~/.gradle ; cp .github/ci-gradle.properties ~/.gradle/gradle.properties
+
+      - name: Set up JDK 11
+        uses: actions/setup-java@v3
+        with:
+          distribution: temurin
+          java-version: 11
+
+      - name: Setup Gradle
+        uses: gradle/gradle-build-action@v2
+
+      - name: Download Screenshots
+        id: download-artifact
+        uses: dawidd6/action-download-artifact@v2
+        with:
+          workflow: UpdateScreenshots.yml
+          name: screenshots
+          path: preview-screenshots/src/test/snapshots/images
+
+      - name: Run screenshot tests
+        id: verifyPaparazziDebug
+        continue-on-error: true
+        run: ./gradlew preview-screenshots:verifyPaparazziDebug
+
+      - name: Error Screenshot tests
+        if: ${{ hashFiles('preview-screenshots/out/failures/*.png') != '' }}
+        uses: actions/upload-artifact@v3
+        with:
+          name: scrennshot-test-results
+          path: preview-screenshots/out/failures
+
+      - name: Comment PR
+        if: ${{ hashFiles('preview-screenshots/out/failures/*.png') != '' }}
+        uses: thollander/actions-comment-pull-request@v1
+        with:
+          message: |
+            There are differences in Compose previews. Please check your build and download the diff artifact.
+            https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/UpdateScreenshots.yml

@@ -0,0 +1,25 @@
+on:
+  pull_request:
+    branches:
+      - main
+    types: [closed]
+
+jobs:
+  update-screenshot:
+    runs-on: ubuntu-latest
+    if: github.event.pull_request.merged == true
+
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-java@v3
+        with:
+          java-version: '11'
+      - name: Run Update Screenshots
+        run: ./gradlew recordPaparazziDebug
+
+      - name: Upload Screenshots
+        uses: actions/upload-artifact@v3
+        with:
+          name: screenshots
+          path: preview-screenshots/src/test/snapshots/images
+          retention-days: 15

core-ui/build.gradle.kts

@@ -1,10 +1,12 @@
+// TODO: Remove once https://youtrack.jetbrains.com/issue/KTIJ-19369 is fixed
 plugins {
     id("droidkaigi.primitive.android")
     id("droidkaigi.primitive.android.kotlin")
     id("droidkaigi.primitive.android.compose")
     id("droidkaigi.primitive.android.hilt")
     id("droidkaigi.primitive.molecule")
     id("droidkaigi.primitive.spotless")
+    id("droidkaigi.primitive.android.compose.showkase")
 }
 
 android.namespace = "io.github.droidkaigi.confsched2022.template.core.ui"

feature-contributors/build.gradle.kts

@@ -1,5 +1,7 @@
+// TODO: Remove once https://youtrack.jetbrains.com/issue/KTIJ-19369 is fixed
 plugins {
     id("droidkaigi.convention.androidfeature")
+    id("droidkaigi.primitive.android.compose.showkase")
 }
 
 android.namespace = "io.github.droidkaigi.confsched2022.feature.contributors"

feature-sessions/build.gradle.kts

@@ -1,5 +1,7 @@
+// TODO: Remove once https://youtrack.jetbrains.com/issue/KTIJ-19369 is fixed
 plugins {
     id("droidkaigi.convention.androidfeature")
+    id("droidkaigi.primitive.android.compose.showkase")
 }
 
 android.namespace = "io.github.droidkaigi.confsched2022.feature.sessions"

feature-sessions/src/main/java/io/github/droidkaigi/confsched2022/feature/sessions/Search.kt

@@ -286,7 +286,7 @@ private fun SearchedItem(
 }
 
 @Composable
-private fun FullScreenLoading(modifier: Modifier = Modifier) {
+fun FullScreenLoading(modifier: Modifier = Modifier) {
     Box(
         modifier = modifier.fillMaxSize(),
         contentAlignment = Alignment.Center,
@@ -297,7 +297,7 @@ private fun FullScreenLoading(modifier: Modifier = Modifier) {
 
 @Preview(showSystemUi = true)
 @Composable
-private fun SearchScreenPreview() {
+fun SearchScreenPreview() {
     SearchScreen(
         uiModel = SearchUiModel(
             state = Success(DroidKaigiSchedule.fake())

gradle/libs.versions.toml

@@ -44,6 +44,10 @@ kluent = "1.68"
 coilCompose = "2.2.1"
 koin = "3.2.1"
 androidXChromeCustomTabs = "1.4.0"
+ksp = "1.7.10-1.0.6"
+paparazzi = "1.0.0"
+showkase = "1.0.0-beta13"
+testParameterInjector = "1.8"
 mokoResources = "0.20.1"
 detekt = '1.21.0'
 
@@ -62,6 +66,8 @@ firebasePlugin = { module = "com.google.gms:google-services", version.ref = "fir
 mokoResourcesPlugin = { module = "dev.icerock.moko:resources-generator", version.ref = "mokoResources" }
 androidDesugarJdkLibs = { group = "com.android.tools", name = "desugar_jdk_libs", version.ref = "androidDesugarJdkLibs" }
 detektGradlePlugin = { module = "io.gitlab.arturbosch.detekt:detekt-gradle-plugin", version.ref = "detekt" }
+kspGradlePlugin = { module = "com.google.devtools.ksp:com.google.devtools.ksp.gradle.plugin", version.ref = "ksp" }
+paparazziGradlePlugin = { module = "app.cash.paparazzi:paparazzi-gradle-plugin", version.ref = "paparazzi" }
 
 composeRuntime = { module = "androidx.compose.runtime:runtime", version.ref = "compose" }
 composeUi = { module = "androidx.compose.ui:ui", version.ref = "compose" }
@@ -132,11 +138,16 @@ androidxTestEspressoEspressoCore = { module = "androidx.test.espresso:espresso-c
 hiltAndroidTesting = { group = "com.google.dagger", name = "hilt-android-testing", version.ref = "dagger" }
 robolectric = { module = "org.robolectric:robolectric", version.ref = "robolectric" }
 kluentAndroid = { module = "org.amshove.kluent:kluent-android", version.ref = "kluent" }
+showkaseRuntime = { group = "com.airbnb.android", name = "showkase", version.ref = "showkase" }
+showkaseProcessor = { group = "com.airbnb.android", name = "showkase-processor", version.ref = "showkase" }
+testParameterInjector = { group = "com.google.testparameterinjector", name = "test-parameter-injector", version.ref = "testParameterInjector" }
 
 [plugins]
 androidGradlePlugin = { id = "com.android.application", version.ref = "androidGradlePlugin" }
 androidGradleLibraryPlugin = { id = "com.android.library", version.ref = "androidGradlePlugin" }
 kotlinPlugin = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }
 hiltGradlePlugin = { id = "com.google.dagger.hilt.android", version.ref = "dagger" }
+kspPlugin = { id = "com.google.devtools.ksp", version.ref = "ksp" }
+paparazziPlugin = { id = "app.cash.paparazzi", version.ref = "paparazzi" }
 sqldelightGradlePlugin = { id = "com.squareup.sqldelight", version.ref = "sqldelight" }
 detektPlugin = { id = "io.gitlab.arturbosch.detekt", version.ref = "detekt" }

gradle/plugins/build.gradle.kts

@@ -27,6 +27,8 @@ dependencies {
     implementation(libs.sqldelightGradlePlugin)
     implementation(libs.detektGradlePlugin)
     implementation(libs.mokoResourcesPlugin)
+    implementation(libs.kspGradlePlugin)
+    implementation(libs.paparazziGradlePlugin)
 }
 
 gradlePlugin {
@@ -108,7 +110,14 @@ gradlePlugin {
             id = "droidkaigi.primitive.detekt"
             implementationClass = "io.github.droidkaigi.confsched2022.primitive.DetektPlugin"
         }
-
+        register("paparazzi") {
+            id = "droidkaigi.primitive.android.paparazzi"
+            implementationClass = "io.github.droidkaigi.confsched2022.primitive.PaparazziPlugin"
+        }
+        register("showkase") {
+            id = "droidkaigi.primitive.android.compose.showkase"
+            implementationClass = "io.github.droidkaigi.confsched2022.primitive.ShowkasePlugin"
+        }
         // Conventions
         register("androidFeature") {
             id = "droidkaigi.convention.androidfeature"

gradle/plugins/src/main/kotlin/io/github/droidkaigi/confsched2022/primitive/KotlinGradleDsl.kt

@@ -22,4 +22,10 @@ fun DependencyHandlerScope.kaptTest(
 
 fun TestedExtension.kotlinOptions(block: KotlinJvmOptions.() -> Unit) {
     (this as ExtensionAware).extensions.configure("kotlinOptions", block)
+}
+
+fun DependencyHandlerScope.ksp(
+    artifact: Optional<Provider<MinimalExternalModuleDependency>>
+) {
+    add("ksp", artifact.get())
 }

gradle/plugins/src/main/kotlin/io/github/droidkaigi/confsched2022/primitive/PaparazziPlugin.kt

@@ -0,0 +1,13 @@
+package io.github.droidkaigi.confsched2022.primitive
+
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+
+@Suppress("unused")
+class PaparazziPlugin : Plugin<Project> {
+    override fun apply(target: Project) {
+        with(target) {
+            pluginManager.apply("app.cash.paparazzi")
+        }
+    }
+}

gradle/plugins/src/main/kotlin/io/github/droidkaigi/confsched2022/primitive/ShowkasePlugin.kt

@@ -0,0 +1,21 @@
+package io.github.droidkaigi.confsched2022.primitive
+
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.kotlin.dsl.dependencies
+import org.gradle.kotlin.dsl.get
+
+@Suppress("unused")
+class ShowkasePlugin : Plugin<Project> {
+    override fun apply(target: Project) {
+        with(target) {
+            with(pluginManager) {
+                apply("com.google.devtools.ksp")
+            }
+            dependencies {
+                implementation(libs.findLibrary("showkaseRuntime"))
+                ksp(libs.findLibrary("showkaseProcessor"))
+            }
+        }
+    }
+}

preview-screenshots/.gitignore

@@ -0,0 +1 @@
+/build

preview-screenshots/build.gradle.kts

@@ -0,0 +1,44 @@
+// TODO: Remove once https://youtrack.jetbrains.com/issue/KTIJ-19369 is fixed
+plugins {
+    id("droidkaigi.primitive.android")
+    id("droidkaigi.primitive.android.kotlin")
+    id("droidkaigi.primitive.android.compose")
+    id("droidkaigi.primitive.molecule")
+    id("droidkaigi.primitive.spotless")
+    id("droidkaigi.primitive.android.compose.showkase")
+    id("droidkaigi.primitive.android.paparazzi")
+}
+
+android.namespace = "io.github.droidkaigi.confsched2022.template.preview.screenshots"
+
+androidComponents {
+    // Disable release builds for this test-only library, no need to run screenshot tests more than
+    // once
+    beforeVariants(selector().withBuildType("release")) { builder ->
+        builder.enable = false
+    }
+    beforeVariants(selector().withBuildType("prod")) { builder ->
+        builder.enable = false
+    }
+}
+
+dependencies {
+
+    implementation(project(":core-ui"))
+    implementation(project(":feature-contributors"))
+    implementation(project(":feature-sessions"))
+
+    implementation(libs.composeUi)
+
+    testImplementation(projects.coreTesting)
+    testImplementation(libs.testParameterInjector)
+}
+
+tasks.named("check") {
+    dependsOn("verifyPaparazziDemoDebug")
+}
+
+tasks.withType<Test>().configureEach {
+    // Increase memory for Paparazzi tests
+    maxHeapSize = "2g"
+}

preview-screenshots/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

preview-screenshots/src/main/AndroidManifest.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+</manifest>

preview-screenshots/src/test/java/io/github/droidkaigi/confsched2022/PreviewScreenshotTests.kt

@@ -0,0 +1,79 @@
+package io.github.droidkaigi.confsched2022
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.platform.LocalInspectionMode
+import androidx.compose.ui.unit.Density
+import app.cash.paparazzi.DeviceConfig
+import app.cash.paparazzi.Paparazzi
+import app.cash.paparazzi.androidHome
+import app.cash.paparazzi.detectEnvironment
+import com.airbnb.android.showkase.models.Showkase
+import com.airbnb.android.showkase.models.ShowkaseBrowserComponent
+import com.google.testing.junit.testparameterinjector.TestParameter
+import com.google.testing.junit.testparameterinjector.TestParameter.TestParameterValuesProvider
+import com.google.testing.junit.testparameterinjector.TestParameterInjector
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+class ComponentPreview(
+    private val showkaseBrowserComponent: ShowkaseBrowserComponent
+) {
+    val content: @Composable () -> Unit = showkaseBrowserComponent.component
+    override fun toString(): String = showkaseBrowserComponent.componentKey
+}
+
+@RunWith(TestParameterInjector::class)
+class PreviewScreenshotTests {
+
+    object PreviewProvider : TestParameterValuesProvider {
+        override fun provideValues(): List<ComponentPreview> =
+            Showkase.getMetadata().componentList.map(::ComponentPreview)
+    }
+
+    enum class BaseDeviceConfig(
+        val deviceConfig: DeviceConfig,
+    ) {
+        NEXUS_5(DeviceConfig.NEXUS_5),
+        PIXEL_5(DeviceConfig.PIXEL_5),
+        PIXEL_C(DeviceConfig.PIXEL_C),
+    }
+
+    @get:Rule
+    val paparazzi = Paparazzi(
+        environment = detectEnvironment().copy(
+            platformDir = "${androidHome()}/platforms/android-31",
+            compileSdkVersion = 31
+        ),
+        maxPercentDifference = 0.0,
+    )
+
+    @Test
+    fun preview_tests(
+        @TestParameter(valuesProvider = PreviewProvider::class) componentPreview: ComponentPreview,
+        @TestParameter baseDeviceConfig: BaseDeviceConfig,
+        @TestParameter(value = ["1.0", "1.5"]) fontScale: Float
+    ) {
+        paparazzi.unsafeUpdateConfig(
+            baseDeviceConfig.deviceConfig.copy(
+                softButtons = false,
+            )
+        )
+        paparazzi.snapshot {
+            CompositionLocalProvider(
+                LocalInspectionMode provides true,
+                LocalDensity provides Density(
+                    density = LocalDensity.current.density,
+                    fontScale = fontScale
+                )
+            ) {
+                Box {
+                    componentPreview.content()
+                }
+            }
+        }
+    }
+}