running-tests-on-gradle-managed-devices

Running Tests On Gradle Managed Devices — Gradle Owns The Emulator

Gradle Managed Devices (GMD) move the emulator into the build: you declare devices in build.gradle.kts, and ./gradlew <device>DebugAndroidTest downloads the system image, boots a fresh emulator, runs androidTest, collects results, and shuts it down. The payoff is reproducibility — CI and every machine run the exact same device — and no hand-managed emulators. This skill covers the DSL, the generated tasks, ATD images for cheap CI, sharding, and where GMD sits relative to connectedAndroidTest and raw am instrument (see ../../../adb/tests/running-instrumented-tests-via-adb/SKILL.md).

When to use this skill

• The user wants instrumented tests to run on a defined, reproducible emulator in CI without adb-managing a device.
• The user mentions managedDevices, allDevicesCheck, ManagedVirtualDevice, or a generated task like pixel2api30DebugAndroidTest.
• The user wants the test matrix (which API levels / form factors) to live in version control, not in someone's local AVD list.
• CI emulator runs are slow/flaky and the user asks about ATD ("Automated Test Device") images.
• The user wants to shard a slow instrumented suite across several emulator copies.

When NOT to use this skill

• The user wants to run tests on a physical device or an emulator they already have running — that is ./gradlew connectedAndroidTest / connectedDebugAndroidTest; GMD is for emulators Gradle creates.
• The user is invoking the runner directly without Gradle (adb shell am instrument -w -r …, sharding via -e numShards, Test Orchestrator wiring) — use ../../../adb/tests/running-instrumented-tests-via-adb/SKILL.md and ../../../adb/automation/scripting-adb-for-ci/SKILL.md.
• The user is choosing the AndroidJUnit4 runner / writing the test class itself — use ../../runner/running-instrumented-tests-with-androidjunit4/SKILL.md.
• The user wants Compose UI tests specifically — those still run as instrumented tests; GMD just hosts them. See ../../../compose/setup/setting-up-host-vs-device-tests/SKILL.md for host-vs-device choice first.

Prerequisites

• Android Gradle Plugin with GMD support (the stable managedDevices DSL; older AGP exposed parts of it under android.testOptions.managedDevices experimentally — check the docs for your AGP version).
• androidTest set up normally: testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner", androidTestImplementation dependencies. GMD changes where tests run, not how they are written.
• Disk space and a working KVM/HAXM/hypervisor on the build machine (CI runners need KVM enabled) — GMD launches a real emulator.
• License acceptance for the system images GMD downloads (sdkmanager --licenses, or accepted in CI setup).

Workflow

• 1. Declare the managed devices. In the module's build.gradle.kts:

android {
    testOptions {
        managedDevices {
            localDevices {
                create("pixel6api34") {
                    device = "Pixel 6"          // a Device Manager profile name
                    apiLevel = 34
                    systemImageSource = "aosp"  // "aosp" | "google" | "google_apis_playstore" | "aosp-atd" | "google-atd"
                }
                create("pixel2api30") {
                    device = "Pixel 2"
                    apiLevel = 30
                    systemImageSource = "aosp-atd"  // ATD: stripped-down, headless, faster — good for CI
                }
            }
            groups {
                create("ciMatrix") {
                    targetDevices.add(localDevices["pixel6api34"])
                    targetDevices.add(localDevices["pixel2api30"])
                }
            }
        }
    }
}

Each create("name") { … } is a ManagedVirtualDevice: device is a Device Manager profile, apiLevel the system image API, systemImageSource which image family. Use require64Bit = true if you need to force the 64-bit image. A group bundles devices so one task runs the suite across all of them.

• 2. Run the generated tasks. GMD synthesizes a task per device, per group, and an all-devices task:

./gradlew pixel6api34DebugAndroidTest          # androidTest on one managed device
./gradlew ciMatrixGroupDebugAndroidTest        # androidTest on every device in the "ciMatrix" group
./gradlew allDevicesCheck                      # androidTest on ALL managed devices defined in the project

Variant naming follows the build variant (…DebugAndroidTest, …ReleaseAndroidTest, flavor-prefixed if you have flavors). These tasks: download the system image if missing, boot a fresh emulator, install the app + test APKs, run the suite, write results, and tear the emulator down — no adb choreography from you.

• 3. Read the results. Per-device HTML reports land under app/build/reports/androidTests/managedDevice/<deviceName>/ (and an aggregated report when running a group / allDevicesCheck); machine-readable results under app/build/outputs/androidTest-results/managedDevice/; anything your tests route through TestStorage / additional test output under app/build/outputs/managed_device_android_test_additional_output/<deviceName>/. Wire those paths into the CI artifact archive.

• 4. Prefer ATD images for CI. Automated Test Device images (systemImageSource = "aosp-atd" or "google-atd") are pared down for headless test execution — no setup wizard, no UI niceties, smaller, faster to boot, lower memory. They keep the Google APIs you usually need for tests (the google-atd variant) without the Play Store. Use a full image only when a test genuinely needs Play services / Play Store behavior.

• 5. Shard a slow suite across emulator copies. GMD can run the suite on N copies of a managed device in parallel, splitting tests across them, via the documented Gradle property (e.g. -Pandroid.experimental.androidTest.numManagedDeviceShards=N) and --max-concurrent-shards to cap how many run at once. Distribution is hash-bucketed by test name, same as am instrument -e numShards. Check the GMD docs for the exact property name on your AGP version before relying on it.

• 6. CI wiring. A GMD task is a normal Gradle task; CI just needs KVM and accepted licenses:

# .github/workflows/instrumented-tests.yml
jobs:
  androidTest:
    runs-on: ubuntu-latest
    timeout-minutes: 45
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-java@v4
        with: { distribution: zulu, java-version: 17 }
      - name: Enable KVM
        run: |
          echo 'KERNEL=="kvm", GROUP="kvm", MODE="0666", OPTIONS+="static_node=kvm"' | sudo tee /etc/udev/rules.d/99-kvm4all.rules
          sudo udevadm control --reload-rules && sudo udevadm trigger --name-match=kvm
      - run: ./gradlew pixel2api30DebugAndroidTest   # ATD device declared above
      - uses: actions/upload-artifact@v4
        if: always()
        with:
          name: androidTest-report
          path: |
            app/build/reports/androidTests/managedDevice/
            app/build/outputs/managed_device_android_test_additional_output/

The emulator is headless by default. (If you need to watch it locally — debugging a UI test — see the GMD docs for the option to show the emulator window; it is off in CI.)

Patterns

Pattern: using connectedAndroidTest in CI and managing the emulator by hand

# WRONG — boot an emulator with adb/avdmanager scripting, then connectedAndroidTest
- run: |
    avdmanager create avd -n ci -k 'system-images;android-30;default;x86_64'
    emulator -avd ci -no-window -no-snapshot &
    adb wait-for-device shell 'while [[ -z $(getprop sys.boot_completed) ]]; do sleep 1; done'
    ./gradlew connectedDebugAndroidTest
# WRONG because: every repo reinvents this, the device definition is not in version control, and
# "works on my machine" diverges from CI. GMD makes the device a build input, provisioned identically everywhere.

// RIGHT — declare it once in build.gradle.kts; CI just runs the task
android { testOptions { managedDevices { localDevices { create("ciDevice") {
    device = "Pixel 2"; apiLevel = 30; systemImageSource = "aosp-atd"
} } } } }
// CI:  ./gradlew ciDeviceDebugAndroidTest

Pattern: full system image in CI when ATD would do

// WRONG
create("ciDevice") { device = "Pixel 6"; apiLevel = 34; systemImageSource = "google_apis_playstore" }
// WRONG because: the Play Store image is the heaviest one — slow to download, slow to boot, more RAM —
// and the test suite does not exercise Play Store behavior. CI minutes burn for nothing.

// RIGHT — ATD: headless, stripped, keeps the Google APIs tests usually need
create("ciDevice") { device = "Pixel 6"; apiLevel = 34; systemImageSource = "google-atd" }

Pattern: expecting GMD task $? to be the only signal

# WRONG — assume a green exit code means everything passed and stop there
./gradlew allDevicesCheck && echo "all good"
# WRONG because: Gradle does fail the build on test failures here (unlike raw `am instrument`), but a
# device that fails to provision, an OOM-killed emulator, or a flaky boot can also fail the task with
# nothing useful on stdout. Always archive app/build/reports/androidTests/managedDevice/ so a failure is diagnosable.

# RIGHT — keep the reports regardless of outcome
- run: ./gradlew allDevicesCheck
- uses: actions/upload-artifact@v4
  if: always()
  with: { name: androidTest-report, path: app/build/reports/androidTests/managedDevice/ }

Mandatory rules

• MUST declare managed devices in android.testOptions.managedDevices in version control — the test device matrix is a build input, not a per-machine AVD.
• MUST prefer ATD images (aosp-atd / google-atd) for CI; use a full or Play Store image only when a test needs GMS / Play Store behavior.
• MUST enable KVM (or the platform hypervisor) on CI runners and accept SDK licenses before invoking a GMD task — otherwise the emulator never boots.
• MUST archive app/build/reports/androidTests/managedDevice/ (and …/managed_device_android_test_additional_output/) on every run, pass or fail, so failures are diagnosable.
• MUST NOT hand-script avdmanager/emulator/adb wait-for-device and then run connectedAndroidTest when GMD applies — GMD owns provisioning, boot, and teardown.
• MUST NOT assume a managed-device task's exit code distinguishes test failures from infra failures; read the HTML report.
• PREFERRED: group devices (groups { create("ciMatrix") { … } }) and run ciMatrixGroupDebugAndroidTest so the matrix is one task; use allDevicesCheck for the full sweep.
• PREFERRED: shard slow suites with the documented numManagedDeviceShards property + --max-concurrent-shards rather than splitting the suite manually.

Verification

• ./gradlew tasks --all | grep -i AndroidTest lists the generated <deviceName>DebugAndroidTest, <groupName>GroupDebugAndroidTest, and allDevicesCheck tasks.
• ./gradlew <deviceName>DebugAndroidTest boots an emulator, runs androidTest, and produces app/build/reports/androidTests/managedDevice/<deviceName>/index.html.
• The device definitions are in build.gradle.kts (committed), not relying on a local AVD.
• CI runs a GMD task with KVM enabled and uploads the managed-device report directory with if: always().
• CI devices use an ATD image (*-atd) unless a specific test documents why it needs a full/Play Store image.

References

• developer.android.com/studio/test/gradle-managed-devices — the managedDevices / localDevices DSL, ManagedVirtualDevice (device, apiLevel, systemImageSource, require64Bit), device groups, the generated <device>…AndroidTest / <group>Group…AndroidTest / allDevicesCheck tasks, ATD images, sharding (numManagedDeviceShards, --max-concurrent-shards), report/output locations, and showing the emulator window.
• developer.android.com/studio/test/advanced-test-setup — testOptions.animationsDisabled, Test Orchestrator, sharding context that also applies to GMD runs.
• developer.android.com/training/testing/instrumented-tests — instrumented test fundamentals; GMD is one execution environment for them.
• developer.android.com/tools/adb — adb and am instrument, for the lower-level alternative when GMD is not in play.
• Sibling skill: ../../runner/running-instrumented-tests-with-androidjunit4/SKILL.md — the AndroidJUnit4 runner the tests use, regardless of where they execute.
• Cross-set: ../../../adb/tests/running-instrumented-tests-via-adb/SKILL.md — running the same tests via adb shell am instrument -w -r without Gradle.
• Cross-set: ../../../adb/automation/scripting-adb-for-ci/SKILL.md — CI bash idioms, sharding via -e numShards, Test Orchestrator wiring, capture-on-failure.
• Cross-set: ../../../compose/preview/capturing-preview-screenshots-in-ci/SKILL.md — uses a managed device (or android-emulator-runner) to render @Preview screenshots in CI.