/android-e2e-testing

name: android-e2e-testing
description: Test Expo Router features on Android emulators using ADB. Use after implementing native Android features or when verifying UI behavior on Android.
user-invokable: true

Android E2E Testing for Expo Router

Use `adb` to manually test Expo Router screens and components on Android emulators.

When to Use

• After implementing or modifying native Android UI components (toolbars, tabs, menus)
• When verifying Jetpack Compose components (`@expo/ui/jetpack-compose`)
• When running the `native-navigation` or other E2E apps on Android
• Before opening a PR that touches Android-specific behavior

Prerequisites

An Android emulator must be running. Prefer **Pixel emulators** over tablet ones for standard phone-sized testing.

# Verify emulator is connected
adb devices

# Check which emulator is running
adb -s DEVICE_ID emu avd name

# Check screen resolution (important for coordinate calculations)
adb -s DEVICE_ID shell wm size

Step 1: Build and Launch

Router E2E apps

Package name: `dev.expo.routere2e`

Each app in `apps/router-e2e/__e2e__/` has a corresponding `yarn android:<name>` script. Check `apps/router-e2e/package.json` for available scripts.

cd apps/router-e2e
yarn android:[APP_NAME]   # e.g. yarn android:native-navigation

If the app is already built, relaunch it:

adb shell monkey -p dev.expo.routere2e -c android.intent.category.LAUNCHER 1

To find the package name of any installed app:

adb shell pm list packages | grep -i <keyword>

Step 2: Navigate Using UI Dump

**CRITICAL: Always use `uiautomator dump` for element coordinates.** Screenshot pixel coordinates have display scaling factors that make them unreliable for `adb shell input tap`. The UI dump provides actual device coordinates.

Dump the view hierarchy

adb shell uiautomator dump /sdcard/ui.xml && adb shell cat /sdcard/ui.xml

This returns XML with every UI element including:

• `text` — displayed text
• `content-desc` — accessibility description (useful for icon buttons)
• `bounds` — position as `[left,top][right,bottom]`
• `clickable` — whether the element responds to taps
• `class` — Android view class

Find and tap an element

1. Search the XML for your target element by `text` or `content-desc` 2. Extract the `bounds` attribute: `bounds="[left,top][right,bottom]"` 3. Calculate center: `x = (left + right) / 2`, `y = (top + bottom) / 2` 4. Tap:

adb shell input tap <x> <y>

**Example:** For `bounds="[367,498][714,633]"`:

• x = (367 + 714) / 2 = 540
• y = (498 + 633) / 2 = 565

adb shell input tap 540 565

Wait for navigation to settle

After tapping a navigation element, wait before verifying:

sleep 1

For slow transitions or heavy screens, use `sleep 2`.

Step 3: Interact

Tap items

adb shell input tap <x> <y>

Scroll

# Scroll down
adb shell input swipe 540 1500 540 500 300

# Scroll up
adb shell input swipe 540 500 540 1500 300

# Scroll further (larger distance)
adb shell input swipe 540 1500 540 200 500

Type text

adb shell input text "hello%sworld"   # %s = space

Press hardware buttons

adb shell input keyevent 4    # Back
adb shell input keyevent 3    # Home
adb shell input keyevent 82   # Menu / React Native dev menu

Long press

adb shell input swipe <x> <y> <x> <y> 1000

Step 4: Verify

Visual verification via screenshot

adb shell screencap -p /sdcard/screenshot.png && adb pull /sdcard/screenshot.png /tmp/screenshot.png

Then use the `Read` tool to view `/tmp/screenshot.png`. Screenshots are useful for:

• Confirming visual appearance (colors, layout, styling)
• Verifying toolbar/tab positioning
• Checking selection states and visual feedback

**Note:** Use screenshots for _visual_ verification only. For element positions and tapping, always use `uiautomator dump`.

Programmatic verification via UI dump

adb shell uiautomator dump /sdcard/ui.xml && adb shell cat /sdcard/ui.xml

Search the XML for expected content:

• Verify text content appears
• Check `content-desc` for accessibility labels
• Confirm element presence after navigation
• Verify selection states (look for checkmarks, content-desc changes)

Check for errors

# React Native JS errors
adb logcat -d -s ReactNativeJS:E | tail -20

# Crash logs
adb logcat -b crash -d

# All recent errors
adb logcat -d *:E | tail -30

Step 5: Report Results

After testing, summarize results in a table:

| Test | Result | | --------------------------- | --------- | | Navigation to screen | PASS/FAIL | | Component renders correctly | PASS/FAIL | | Interaction works | PASS/FAIL | | No JS errors in logcat | PASS/FAIL |

Include details for any failures: what was expected vs what happened, relevant logcat output, and screenshots.

Preferably attach screenshots for features you tested.

Testing Jetpack Compose Components

Components from `@expo/ui/jetpack-compose` (like `HorizontalFloatingToolbar`, `IconButton`, `Host`) render as Compose views inside React Native. In UI dumps they appear as:

• `androidx.compose.ui.platform.ComposeView` — the Compose container
• `android.widget.HorizontalScrollView` — inside toolbar layouts
• `android.widget.Button` — Compose buttons
• `android.view.View` with `content-desc` — icon buttons with accessibility labels

When testing Compose components:

1. Look for `content-desc` attributes to identify buttons (e.g., `content-desc="Clear selection"`) 2. The `ComposeView` wrapper may have different bounds than the inner interactive elements 3. Tap the interactive element's bounds, not the container's

Troubleshooting

uiautomator dump fails or returns empty

This can happen during animations or transitions. Wait and retry:

sleep 2 && adb shell uiautomator dump /sdcard/ui