device-testing

name	device-testing
description	Interact with iOS simulators and verify app behavior using xcobra

Use bunx xcobra to interact with iOS simulators and debug Expo apps.

Inspecting the UI

Get the accessibility tree to understand current screen state:

bunx xcobra sim xml

This returns XML with all UI elements, their labels, identifiers, and positions. Use this to:

• Find element identifiers for tapping
• Verify UI state after actions
• Debug layout issues

Tapping Elements

Tap by accessibility label (preferred):

bunx xcobra sim tap --label "Submit"

Tap by accessibility identifier:

bunx xcobra sim tap --id "submit-button"

Tap by coordinates:

bunx xcobra sim tap --x 200 --y 400

Add delays for animations:

bunx xcobra sim tap --label "Next" --pre-delay 500 --post-delay 300

Typing Text

Type text into focused input:

bunx xcobra sim type "Hello World"

Type from stdin:

echo "[e-mail]" | bunx xcobra sim type --stdin

Gestures

Preset gestures:

bunx xcobra sim gesture scroll-up
bunx xcobra sim gesture scroll-down
bunx xcobra sim gesture swipe-from-left-edge

Custom swipe:

bunx xcobra sim swipe --start-x 200 --start-y 400 --end-x 200 --end-y 100

Hardware Buttons

Press hardware buttons:

bunx xcobra sim button home
bunx xcobra sim button lock
bunx xcobra sim button siri

Screenshots

Capture screenshot:

bunx xcobra sim screenshot --output screenshot.png

Video Recording

Record simulator video:

bunx xcobra sim record-video --output recording.mp4

Evaluating JavaScript

Execute JS in the running Expo app:

bunx xcobra expo eval "Date.now()"

Get app state:

bunx xcobra expo eval "global.__REDUX_STORE__?.getState()"

Call exposed functions:

bunx xcobra expo eval "globalThis.testHelper?.getCurrentRoute()"

Console Logs

Stream console output:

bunx xcobra expo console

JSON format for parsing:

bunx xcobra expo console --json

Network Monitoring

Monitor network requests:

bunx xcobra expo network

Reloading the App

Trigger a reload to refresh the JavaScript bundle:

bunx xcobra expo reload

This is useful when:

• The Metro connection becomes stale
• Hot reload isn't picking up changes
• The app state needs a fresh start
• Deep links or navigation seem stuck

Crash Reports

View latest crash:

bunx xcobra crash latest

List recent crashes:

bunx xcobra crash list

Show specific crash:

bunx xcobra crash show <crash-id>

Source Inspection

List loaded scripts:

bunx xcobra expo src scripts

Get source code by script ID:

bunx xcobra expo src source <script-id>

List Metro modules:

bunx xcobra expo src modules

Simulator Management

List all simulators:

bunx xcobra sim list

Target specific simulator:

bunx xcobra sim tap --udid "DEVICE-UDID" --label "OK"

Testing Workflow

1. Get current UI state

   bunx xcobra sim xml
   

2. Perform action

   bunx xcobra sim tap --label "Login"
   

3. Wait and verify

   sleep 1
   bunx xcobra sim xml | grep "Welcome"
   

4. Check for errors

   bunx xcobra expo console --json | head -20
   

Verifying Screen Content

After navigating, verify you're on the expected screen:

# Check for expected text content
bunx xcobra sim xml | grep -i "expected title"

# Get full accessibility tree and search for elements
bunx xcobra sim xml > /tmp/ui.xml && cat /tmp/ui.xml

Use JavaScript eval to check the current route:

bunx xcobra expo eval "window.location?.pathname"

Troubleshooting Unexpected Routes

If deep links navigate to the wrong screen or you see unexpected content:

1. Check the current route in the app:

bunx xcobra expo eval "globalThis.testHelper?.getCurrentRoute()"

2. Verify the app directory structure:

Look for unexpected index routes that may be intercepting navigation:

# List all index files - these define default routes
find app -name "index.tsx" -o -name "index.ts" -o -name "index.js"

# Check for index routes inside groups that may override expected behavior
find app -path "*/(*)/*" -name "index.*"

3. Common issues:

• Unexpected index in a group: A file like app/(tabs)/index.tsx will be the default route for the (tabs) group, potentially overriding app/index.tsx
• Missing layout: Groups need a _layout.tsx to properly nest routes
• Conflicting routes: Two files resolving to the same URL path

4. Verify route structure matches expectations:

# List all route files
find app -name "*.tsx" | grep -v "_layout" | sort

# Check group structure
find app -type d -name "(*)"`

5. Test deep link resolution:

# Open a deep link and immediately check the route
xcrun simctl openurl booted "myapp://settings" && sleep 1 && bunx xcobra expo eval "window.location?.pathname"

Exposing Test Helpers

Add global helpers in your app for testing:

if (__DEV__) {
  globalThis.testHelper = {
    getCurrentRoute: () => navigationRef.current?.getCurrentRoute(),
    getState: () => store.getState(),
    resetApp: () => { /* reset logic */ },
  };
}

Then call via eval:

bunx xcobra expo eval "testHelper.getCurrentRoute()"