Node / meshtastic / Meshtastic-Android / files / feature / car / TESTING.md

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Tc9d1d9# Testing the Car (Android Auto) feature

Two ways to verify Ta5d6ff`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.

Tc9d1d9## 1. Automated — `SessionController` tests (no hardware, runs in CI)

Ta5d6ff```Ta5d6ffbash

./gradlew :feature:car:testGoogleDebugUnitTest

Ta5d6ff```

Ta5d6ff`CarScreensTest` drives the real Ta5d6ff`HomeScreen` through the androidx.car.app testing context, pushing

state via the Ta5d6ff`CarStateCoordinator` test seam (Ta5d6ff`setStateForTest`), and asserts the right template

renders per connection state plus the Ta5d6ff`ALERT_APP` → emergency flow. This is what catches regressions

(e.g. it caught the Ta5d6ff`TabTemplate.setActiveTabContentId` crash the 1.7.0 pin introduced). Robolectric

is pinned to Ta5d6ff`@Config(sdk = [36])` because no Robolectric SDK-37 sandbox exists yet — harmless, the

templates are SDK-agnostic.

Tc9d1d9## 2. Visual — Desktop Head Unit (DHU)

Tc9d1d9### Platform matters

DHU decodes an H.264 video stream from the phone. **macOS Apple Silicon (Ta5d6ff`2.1-mac-arm64`) fails at

this step** — it connects and reports Ta5d6ff`Has video focus: true` but renders no frames. Use an

**x86_64 Linux (or Windows) host**; Ta5d6ff`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**.

Tc9d1d9### Phone prep (one time)

Tff7b721. Settings → About → tap *Build number* ×7 → enable **USB debugging** and **Wireless debugging**.

Tff7b722. Open Android Auto settings (on a Pixel: Ta5d6ff`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**.

Tc9d1d9### On the x86_64 box

Ta5d6ff```Ta5d6ffbash

sdkmanager Ta5d6ff"extras;google;auto" T8b949e# installs the linux-x86_64 DHU

T8b949e# Connect to the phone over wifi (no re-plugging; works even if the phone lives on another machine):

adb pair <phone-ip>:<pair-port> T8b949e# one-time; code shown under Wireless debugging

adb connect <phone-ip>:<debug-port>

adb forward tcp:5277 tcp:5277

Tffa657cd Ta5d6ff"Te6edf3$ANDROID_SDK_ROOTTa5d6ff/extras/google/autoTa5d6ff" Tff7b72&& ./desktop-head-unit

Ta5d6ff```

DHU commands: type Ta5d6ff`help` in its shell; Ta5d6ff`focus video`, Ta5d6ff`tap <x> <y>`, Ta5d6ff`screenshot <file>`.

Tc9d1d9### Caveat: our app has no car-launcher tile

Ta5d6ff`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 Ta5d6ff`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 Ta5d6ff`CarAppActivity`.)