chore: add downgrade compatibility CI

.github/workflows/build.yml

@@ -44,3 +44,47 @@ jobs:
 
       - name: Make stop
         run: make stop
+
+  downgrade-compatibility:
+    name: Downgrade compatibility (${{ matrix.downgrade_version }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        downgrade_version:
+          # Pin persisted-storage schema boundaries rather than the last N releases.
+          # 3.43.3 predates the replay minimum-duration buffer queue.
+          - 3.43.3
+          # 3.45.1 predates the persisted logs queue.
+          - 3.45.1
+          # 3.47.0 includes the logs queue but predates the current captureLog surface.
+          - 3.47.0
+
+    steps:
+      - name: Git checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - name: 'Set up Java 17'
+        uses: actions/setup-java@be666c2fcd27ec809703dec50e508c2fdc7f6654 # v5.2.0
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+
+      - name: Cache Gradle packages
+        uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+          key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*', '**/gradle-wrapper.properties') }}
+          restore-keys: |
+            ${{ runner.os }}-gradle-
+
+      - name: Test downgrade compatibility
+        env:
+          DOWNGRADE_VERSION: ${{ matrix.downgrade_version }}
+        run: make testDowngradeCompatibility
+
+      - name: Make stop
+        if: always()
+        run: make stop

Makefile

@@ -1,4 +1,4 @@
-.PHONY: clean compile stop checkFormat format api dryRelease release testReport test testJava generateLintBaseLine updateLocks
+.PHONY: clean compile stop checkFormat format api dryRelease release testReport test testJava testDowngradeCompatibility generateLintBaseLine updateLocks
 
 clean:
 	./gradlew clean
@@ -61,6 +61,9 @@ test:
 testJava:
 	./gradlew :posthog:test
 
+testDowngradeCompatibility:
+	DOWNGRADE_VERSION="$${DOWNGRADE_VERSION:-3.45.1}" ./scripts/test-downgrade-compatibility.sh
+
 generateLintBaseLine:
 	rm -f posthog-android/lint-baseline.xml
 	./gradlew lintDebug -Dlint.baselines.continue=true

scripts/downgrade-compatibility-smoke/.gitignore

@@ -0,0 +1,2 @@
+.gradle/
+build/

scripts/downgrade-compatibility-smoke/build.gradle

@@ -0,0 +1,34 @@
+plugins {
+    id 'com.android.library' version '8.9.1'
+}
+
+android {
+    namespace 'com.posthog.downgradecompatibility'
+    compileSdk 36
+
+    defaultConfig {
+        minSdk 23
+        testInstrumentationRunner 'androidx.test.runner.AndroidJUnitRunner'
+    }
+
+    testOptions {
+        unitTests {
+            includeAndroidResources = true
+            returnDefaultValues = true
+            all {
+                systemProperty 'posthog.smoke.mode', System.getProperty('posthog.smoke.mode', 'read')
+                systemProperty 'posthog.smoke.stateDir', System.getProperty('posthog.smoke.stateDir', '')
+                systemProperty 'posthog.smoke.apiKey', System.getProperty('posthog.smoke.apiKey', 'downgrade_compatibility_project')
+            }
+        }
+    }
+}
+
+dependencies {
+    String posthogVersion = providers.gradleProperty('posthogVersion').orElse('3.45.1').get()
+
+    testImplementation "com.posthog:posthog-android:${posthogVersion}"
+    testImplementation 'junit:junit:4.13.2'
+    testImplementation 'org.robolectric:robolectric:4.14.1'
+    testImplementation 'com.google.code.gson:gson:2.10.1'
+}

scripts/downgrade-compatibility-smoke/gradle.properties

@@ -0,0 +1 @@
+android.useAndroidX=true

scripts/downgrade-compatibility-smoke/settings.gradle

@@ -0,0 +1,33 @@
+pluginManagement {
+    repositories {
+        google()
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
+
+dependencyResolutionManagement {
+    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
+    repositories {
+        google()
+        mavenCentral()
+    }
+}
+
+rootProject.name = 'posthog-downgrade-compatibility-smoke'
+
+String dependencyMode = settings.startParameter.projectProperties['posthogDependencyMode']
+String dependencyPath = settings.startParameter.projectProperties['posthogDependencyPath']
+
+if (dependencyMode == 'composite') {
+    if (dependencyPath == null || dependencyPath.trim().isEmpty()) {
+        throw new GradleException('posthogDependencyPath is required when posthogDependencyMode=composite')
+    }
+
+    includeBuild(dependencyPath) {
+        dependencySubstitution {
+            substitute(module('com.posthog:posthog')).using(project(':posthog'))
+            substitute(module('com.posthog:posthog-android')).using(project(':posthog-android'))
+        }
+    }
+}