Android: introduce unit tests and Kotlin

Author: ofalvai

.github/workflows/ci-test.yml

@@ -21,8 +21,34 @@ jobs:
       - name: Check public API compatibility
         run: npm run check:api-compat
 
-  android-test:
+  android-unit-test:
     needs: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+
+      - uses: jdx/mise-action@v4
+
+      - name: Cache npm packages
+        uses: actions/cache@v6
+        with:
+          path: ~/.npm
+          key: ${{ runner.os }}-npm-${{ hashFiles('package-lock.json', 'test/test.ts') }}
+          restore-keys: |
+            ${{ runner.os }}-npm-
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v6
+
+      - name: Run Android unit tests
+        working-directory: android
+        run: ./gradlew :app:test
+
+  android-test:
+    needs: [lint, android-unit-test]
     runs-on: bitrise-react-native-code-push-linux-runner
     strategy:
       matrix:
@@ -49,6 +75,16 @@ jobs:
       - name: Install dependencies
         run: npm install
 
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v6
+        with:
+          # This job's Gradle build lives in a test app generated at runtime by the test harness,
+          # not a project checked into this repo, so there's nothing meaningful for it to
+          # contribute back to the cache. Read-only avoids each matrix variant (bare/expo) writing
+          # its own redundant entry; it still reuses whatever android-unit-test wrote, since
+          # setup-gradle shares its cache across jobs in the same workflow run.
+          cache-read-only: true
+
       - name: Enable KVM
         run: |
           echo 'KERNEL=="kvm", GROUP="kvm", MODE="0666", OPTIONS+="static_node=kvm"' | sudo tee /etc/udev/rules.d/99-kvm4all.rules

CLAUDE.md

@@ -7,7 +7,13 @@ React Native CodePush is a native module that enables over-the-air updates for R
 ## Development Commands
 
 ### Testing
-- `npm test` - Run all tests with TypeScript compilation
+
+#### Unit tests
+
+- `cd android && ./gradlew :app:test`
+- iOS: no unit tests yet.
+
+#### E2E Tests
 - `npm run test:android` - Run Android-specific tests
 - `npm run test:ios` - Run iOS-specific tests  
 - `npm run test:setup-android` - Set up Android emulator for testing
@@ -34,7 +40,7 @@ React Native CodePush is a native module that enables over-the-air updates for R
 
 ### Platform Structure
 - **iOS**: `ios/` - Objective-C implementation with CocoaPods integration
-- **Android**: `android/` - Java implementation with Gradle plugin
+- **Android**: `android/` - Java/Kotlin implementation with Gradle plugin
 - **Windows**: `windows/` - C++ implementation for Windows React Native
 - **JavaScript**: Root level - TypeScript definitions and bridge code
 
@@ -48,7 +54,7 @@ React Native CodePush is a native module that enables over-the-air updates for R
 - **Custom Test Runner**: TypeScript-based test framework in `test/`
 - **Real App Testing**: Creates actual React Native apps for integration testing
 - **Scenario Testing**: Update, rollback, and error scenarios
-- **No unit test infra yet**: this repo only has the mocha-based integration suite above. `src/acquisition-sdk/__tests__/` contains tests ported from upstream `microsoft/code-push`, kept for future reference - they are deliberately not wired into `npm test` or any runner. Don't assume they're dead/forgotten code, and don't wire them in without setting up real unit test infra first.
+- **No unit test infra for JS/iOS yet**: JS/iOS only have the mocha-based integration suite above. `src/acquisition-sdk/__tests__/` contains tests ported from upstream `microsoft/code-push`, kept for future reference - they are deliberately not wired into `npm test` or any runner. Don't assume they're dead/forgotten code, and don't wire them in without setting up real unit test infra first.
 - **Templates**: `test/template/` holds native files (Podfile, AppDelegate, Android app files) and JS scenarios copied over top of a freshly generated RN/Expo app during test setup, overwriting its defaults — edit files here, not the generated project, for changes to persist
 - **`test:ios` vs `test:setup:ios` vs `test:fast:ios`**: `test:ios` is just `test:setup:ios` followed by `test:fast:ios` — the two are meant to be split apart for local iteration.
   - `test:setup:ios` (mocha `--ios --setup`) boots the simulator and provisions the test app once: copies templates, runs `pod install`, patches Info.plist/AppDelegate. It never builds or runs any test scenario.

Examples/CodePushDemo/android/gradle.properties

@@ -42,3 +42,9 @@ hermesEnabled=true
 # This allows your app to draw behind system bars for an immersive UI.
 # Note: Only works with ReactActivity and should not be used with custom Activity.
 edgeToEdgeEnabled=false
+
+# Opt out of AGP 9's built-in Kotlin support and new DSL, matching what RN's own 0.87 app template
+# does. See the AGP v9 adoption RFC:
+# https://github.com/react-native-community/discussions-and-proposals/pull/1006).
+android.builtInKotlin=false
+android.newDsl=false

android/app/build.gradle

@@ -1,4 +1,21 @@
-apply plugin: "com.android.library"
+// No versions specified: both plugins are expected to already be resolved on the root project's
+// buildscript classpath, which every RN app template declares (AGP for the app itself, Kotlin
+// because RN ships Kotlin internally).
+// Matches how other RN libraries (e.g. reanimated) apply these plugins.
+plugins {
+    id "com.android.library"
+    id "org.jetbrains.kotlin.android" apply false
+}
+
+// AGP 9 provides Kotlin support built in; applying the classic kotlin-android plugin on top of it
+// leads to a configuration-time failure. Below AGP 9, and on AGP 9+ when `android.builtInKotlin=false`
+// opts back out of built-in Kotlin, the classic plugin is still required.
+// See React Native RFC about ecosystem migration details: https://github.com/react-native-community/discussions-and-proposals/pull/1006
+def agpMajor = com.android.Version.ANDROID_GRADLE_PLUGIN_VERSION.tokenize('.')[0].toInteger()
+def builtInKotlinEnabled = agpMajor >= 9 && (!project.hasProperty("android.builtInKotlin") || Boolean.parseBoolean(project.property("android.builtInKotlin").toString()))
+if (!builtInKotlinEnabled) {
+    apply plugin: "org.jetbrains.kotlin.android"
+}
 
 def isNewArchitectureEnabled() {
     // To opt-in for the New Architecture, you can either:
@@ -10,15 +27,18 @@ def isNewArchitectureEnabled() {
 
 def IS_NEW_ARCHITECTURE_ENABLED = isNewArchitectureEnabled()
 
-def DEFAULT_COMPILE_SDK_VERSION = 26
-def DEFAULT_BUILD_TOOLS_VERSION = "26.0.3"
-def DEFAULT_TARGET_SDK_VERSION = 26
-def DEFAULT_MIN_SDK_VERSION = 16
+// These are fallbacks only. Keep them aligned with RN's current app template
+// so a consumer relying on the fallback still gets a build that actually works
+// with a current RN version.
+def DEFAULT_COMPILE_SDK_VERSION = 35
+def DEFAULT_BUILD_TOOLS_VERSION = "36.0.0"
+def DEFAULT_TARGET_SDK_VERSION = 35 
+def DEFAULT_MIN_SDK_VERSION = 24
 
 android {
     namespace "com.microsoft.codepush.react"
 
-    compileSdkVersion rootProject.hasProperty('compileSdkVersion') ? rootProject.compileSdkVersion : DEFAULT_COMPILE_SDK_VERSION
+    compileSdk rootProject.hasProperty('compileSdkVersion') ? rootProject.compileSdkVersion : DEFAULT_COMPILE_SDK_VERSION
     buildToolsVersion rootProject.hasProperty('buildToolsVersion') ? rootProject.buildToolsVersion : DEFAULT_BUILD_TOOLS_VERSION
 
     defaultConfig {
@@ -40,9 +60,25 @@ android {
     buildFeatures {
         buildConfig true
     }
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_17
+        targetCompatibility JavaVersion.VERSION_17
+    }
+}
+
+// Only set when we applied the classic kotlin-android plugin ourselves above: AGP 9's built-in
+// Kotlin integration doesn't expose this extension at all, per Android's own built-in
+// Kotlin migration guide: https://developer.android.com/build/migrate-to-built-in-kotlin
+if (!builtInKotlinEnabled) {
+    android.kotlinOptions {
+        jvmTarget = "17"
+    }
 }
 
 dependencies {
     implementation 'com.facebook.react:react-android:0.82.1'
     implementation 'com.nimbusds:nimbus-jose-jwt:9.37.3'
+
+    testImplementation 'junit:junit:4.13.2'
 }

android/app/src/test/java/com/microsoft/codepush/react/FileUtilsTest.kt

@@ -0,0 +1,34 @@
+package com.microsoft.codepush.react
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.TemporaryFolder
+import java.io.File
+
+class FileUtilsTest {
+
+    @get:Rule
+    val tempFolder = TemporaryFolder()
+
+    @Test
+    fun copyDirectoryContents_copiesNestedFilesAndSubdirectories() {
+        // Given
+        val sourceDir = tempFolder.newFolder("source")
+        File(sourceDir, "root.txt").writeText("root contents")
+        val nestedDir = File(sourceDir, "nested").apply { mkdir() }
+        File(nestedDir, "child.txt").writeText("child contents")
+
+        val destinationDir = File(tempFolder.root, "destination")
+
+        // When
+        FileUtils.copyDirectoryContents(sourceDir.absolutePath, destinationDir.absolutePath)
+
+        // Then
+        assertEquals("root contents", File(destinationDir, "root.txt").readText())
+        val copiedNestedFile = File(destinationDir, "nested/child.txt")
+        assertTrue(copiedNestedFile.exists())
+        assertEquals("child contents", copiedNestedFile.readText())
+    }
+}

android/build.gradle

@@ -6,7 +6,12 @@ buildscript {
         mavenCentral()
     }
     dependencies {
-        classpath("com.android.tools.build:gradle:8.12.0")
+        // Must match (or exceed) the AGP version RN's own @react-native/gradle-plugin declares: that plugin is
+        // included as a composite build below and its own AGP dependency wins Gradle's classpath
+        // conflict resolution regardless of what's pinned here, so an out-of-date pin here is
+        // silently overridden rather than actually enforced. Bump this in lockstep with RN's own
+        // gradle-plugin version whenever bumping the react-native devDependency.
+        classpath("com.android.tools.build:gradle:9.2.1")
         classpath("com.facebook.react:react-native-gradle-plugin")
 
         // NOTE: Do not place your application dependencies here; they belong

android/gradle.properties

@@ -16,3 +16,10 @@
 # This option should only be used with decoupled projects. More details, visit
 # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
 # org.gradle.parallel=true
+android.useAndroidX=true
+
+# https://github.com/react-native-community/discussions-and-proposals/pull/1006
+# Applies to this repo's own standalone build/test harness only; see android/app/build.gradle's comments
+# for why downstream consumers may still land in either mode.
+android.builtInKotlin=false
+android.newDsl=false

android/gradle/wrapper/gradle-wrapper.properties

@@ -2,4 +2,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.14.3-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.4.1-all.zip