test: Add Compose screenshot testing support

Integrate the experimental Android screenshot testing plugin into the `core:ui` module. This includes initial visual regression tests for Alert components and updates to the CI workflow for automated validation.

- core/ui: Add `AlertScreenshotTest` and screenshot test dependencies
- gradle.properties: Enable `android.experimental.enableScreenshotTest`
- libs.versions.toml: Add `com.android.compose.screenshot` plugin and validation API
- reusable-check.yml: Add screenshot validation tasks to GitHub Actions workflow

.github/workflows/reusable-check.yml

@@ -12,6 +12,9 @@ on:
       run_instrumented_tests:
         type: boolean
         default: true
+      run_screenshot_tests:
+        type: boolean
+        default: true
       flavors:
         type: string
         default: '["google"]'
@@ -110,6 +113,15 @@ jobs:
             fi
           fi
           
+          # Screenshot Test Tasks
+          if [ "${{ inputs.run_screenshot_tests }}" = "true" ] && [ "$IS_FIRST_API" = "true" ]; then
+            if [ "$FLAVOR" = "google" ]; then
+              TASKS="$TASKS validateGoogleDebugScreenshotTest "
+            elif [ "$FLAVOR" = "fdroid" ]; then
+              TASKS="$TASKS validateFdroidDebugScreenshotTest "
+            fi
+          fi
+          
           # Instrumented Test Tasks
           if [ "${{ inputs.run_instrumented_tests }}" = "true" ]; then
             [ "$IS_FIRST_FLAVOR" = "true" ] && TASKS="$TASKS connectedDebugAndroidTest "

core/ui/build.gradle.kts

@@ -21,9 +21,13 @@ plugins {
     alias(libs.plugins.meshtastic.android.library.compose)
     alias(libs.plugins.meshtastic.android.library.flavors)
     alias(libs.plugins.meshtastic.hilt)
+    alias(libs.plugins.screenshot)
 }
 
-configure<LibraryExtension> { namespace = "org.meshtastic.core.ui" }
+configure<LibraryExtension> {
+    namespace = "org.meshtastic.core.ui"
+    experimentalProperties["android.experimental.enableScreenshotTest"] = true
+}
 
 dependencies {
     implementation(projects.core.common)
@@ -55,4 +59,7 @@ dependencies {
     androidTestImplementation(libs.androidx.test.runner)
 
     testImplementation(libs.junit)
+
+    screenshotTestImplementation(libs.screenshot.validation.api)
+    screenshotTestImplementation(libs.androidx.compose.ui.tooling)
 }

core/ui/src/screenshotTest/kotlin/org/meshtastic/core/ui/AlertScreenshotTest.kt

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2025-2026 Meshtastic LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.meshtastic.core.ui
+
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.tooling.preview.Preview
+import com.android.tools.screenshot.PreviewTest
+import org.meshtastic.core.ui.util.PreviewTextAlert
+import org.meshtastic.core.ui.util.PreviewIconAlert
+import org.meshtastic.core.ui.util.PreviewHtmlAlert
+import org.meshtastic.core.ui.util.PreviewMultipleChoiceAlert
+import org.meshtastic.core.ui.util.PreviewComposableAlert
+
+class AlertScreenshotTest {
+
+    @PreviewTest
+    @Preview(showBackground = true)
+    @Composable
+    fun TextAlert() {
+        PreviewTextAlert()
+    }
+
+    @PreviewTest
+    @Preview(showBackground = true)
+    @Composable
+    fun IconAlert() {
+        PreviewIconAlert()
+    }
+
+    @PreviewTest
+    @Preview(showBackground = true)
+    @Composable
+    fun HtmlAlert() {
+        PreviewHtmlAlert()
+    }
+
+    @PreviewTest
+    @Preview(showBackground = true)
+    @Composable
+    fun MultipleChoiceAlert() {
+        PreviewMultipleChoiceAlert()
+    }
+
+    @PreviewTest
+    @Preview(showBackground = true)
+    @Composable
+    fun ComposableAlert() {
+        PreviewComposableAlert()
+    }
+}

gradle.properties

@@ -20,6 +20,9 @@ android.useAndroidX=true
 dependency.analysis.print.build.health=true
 enableComposeCompilerMetrics=false
 enableComposeCompilerReports=false
+android.experimental.enableScreenshotTest=true
+
+# Housekeeping
 kotlin.code.style=official
 kotlin.daemon.jvm.options=-Xmx4g -XX\:+UseParallelGC
 kotlin.parallel.tasks.in.project=true

gradle/libs.versions.toml

@@ -54,6 +54,7 @@ devtools-ksp = "2.3.6"
 markdownRenderer = "0.39.2"
 okio = "3.16.4"
 osmdroid-android = "6.1.20"
+screenshot = "0.0.1-alpha13"
 spotless = "8.2.1"
 wire = "6.0.0-alpha02"
 vico = "3.0.2"
@@ -180,6 +181,7 @@ androidx-test-espresso-core = { module = "androidx.test.espresso:espresso-core",
 junit = { module = "junit:junit", version = "4.13.2" }
 mockk = { module = "io.mockk:mockk", version.ref = "mockk" }
 robolectric = { module = "org.robolectric:robolectric", version = "4.16.1" }
+screenshot-validation-api = { group = "com.android.tools.screenshot", name = "screenshot-validation-api", version.ref = "screenshot" }
 turbine = { module = "app.cash.turbine:turbine", version.ref = "turbine" }
 
 # Other
@@ -282,6 +284,7 @@ detekt = { id = "io.gitlab.arturbosch.detekt", version.ref = "detekt" }
 dokka = { id = "org.jetbrains.dokka", version.ref = "dokka" }
 wire = { id = "com.squareup.wire", version.ref = "wire" }
 room = { id = "androidx.room", version.ref = "room" }
+screenshot = { id = "com.android.compose.screenshot", version.ref = "screenshot" }
 spotless = { id = "com.diffplug.spotless", version.ref = "spotless" }
 test-retry = { id = "org.gradle.test-retry", version.ref = "testRetry" }
 dependency-guard = { id = "com.dropbox.dependency-guard", version.ref = "dependency-guard" }