Meshtastic-Android/feature/car/TESTING.md

Testing the Car (Android Auto) feature

Two ways to verify feature:car. Use the unit tests for correctness; use the DHU only when you want to eyeball the real in-car experience end to end.

1. Automated — SessionController tests (no hardware, runs in CI)

./gradlew :feature:car:testGoogleDebugUnitTest

CarScreensTest drives the real HomeScreen through the androidx.car.app testing context, pushing state via the CarStateCoordinator test seam (setStateForTest), and asserts the right template renders per connection state plus the ALERT_APP → emergency flow. This is what catches regressions (e.g. it caught the TabTemplate.setActiveTabContentId crash the 1.7.0 pin introduced). Robolectric is pinned to @Config(sdk = [36]) because no Robolectric SDK-37 sandbox exists yet — harmless, the templates are SDK-agnostic.

2. Visual — Desktop Head Unit (DHU)

Platform matters

DHU decodes an H.264 video stream from the phone. macOS Apple Silicon (2.1-mac-arm64) fails at this step — it connects and reports Has video focus: true but renders no frames. Use an x86_64 Linux (or Windows) host; linux-arm64 DHU does not exist, and an emulated x86 VM has no hardware decode (same failure). A VM is fine only on an x86_64 host with real virtualization.

Phone prep (one time)

1. Settings → About → tap Build number ×7 → enable USB debugging and Wireless debugging.
2. Open Android Auto settings (on a Pixel: adb shell am start -n com.google.android.projection.gearhead/.companion.settings.DefaultSettingsActivity), tap Version ~10× to unlock Developer settings, then enable Start head unit server.

On the x86_64 box

sdkmanager "extras;google;auto"                 # installs the linux-x86_64 DHU
# Connect to the phone over wifi (no re-plugging; works even if the phone lives on another machine):
adb pair <phone-ip>:<pair-port>                 # one-time; code shown under Wireless debugging
adb connect <phone-ip>:<debug-port>
adb forward tcp:5277 tcp:5277
cd "$ANDROID_SDK_ROOT/extras/google/auto" && ./desktop-head-unit

DHU commands: type help in its shell; focus video, tap <x> <y>, screenshot <file>.

Caveat: our app has no car-launcher tile

feature:car is a MESSAGING-category app. It does not appear as an icon on the Android Auto home — it surfaces when a message notification arrives. To see the ConversationItem UI in the DHU you must have a paired Meshtastic radio sending a text; the notification (read-aloud + reply) is the entry point. Without a radio you'll see the AA home, not our screens. (For the same reason, the AAOS emulator is not a fit either: messaging isn't an AAOS distribution category, and the app is projection-only — no CarAppActivity.)