maestro-mobile-testing

Maestro Mobile E2E Testing

Overview

Maestro is a declarative YAML-based mobile E2E testing framework. It provides automatic waiting, built-in retry logic, and fast execution without boilerplate. It's more stable than Detox or Appium for React Native apps.

Key Features

• Declarative YAML — no imperative test code, just steps
• Automatic waiting — no manual sleep() or flaky waits
• Built-in retry — reduces test flakiness
• Fast execution — runs quickly without setup overhead
• Maestro Studio — interactive test builder (maestro studio)
• Sub-flows — reusable YAML sequences for DRY tests
• JavaScript scripting — GraalJS runtime for HTTP calls and data manipulation
• Maestro Cloud — real device testing in CI without local simulators

Quick Start

Install

curl -Ls "https://get.maestro.mobile.dev" | bash
brew install openjdk@17
export JAVA_HOME=/opt/homebrew/opt/openjdk@17/libexec/openjdk.jdk/Contents/Home

Minimal test

appId: com.myapp
---
- launchApp
- tapOn:
    id: "my-button"
- assertVisible: "Expected Text"

Run

maestro test .maestro/smoke-test.yaml
maestro test --debug .maestro/smoke-test.yaml  # step through
maestro studio                                  # interactive builder

---

Core Patterns

1. Selector Strategy: testID vs Text

Choose your selector approach based on project context. Both are valid — the right choice depends on whether your app is localized and your team's testing philosophy.

Context	Recommended Selector	Rationale
Multi-language / i18n	id: (testID)	Stable across translations
Single language	Text labels	Human-readable, self-documenting tests
Agent-maintained tests	Either — ask the developer	Readability matters less for AI-maintained flows
System dialogs	Text (always)	No testID possible on native alerts

# testID selector — stable across translations
- tapOn:
    id: "submit-button"

# Text selector — human-readable, self-documenting
- tapOn: "Submit"

When to prefer testIDs:

• App supports multiple languages or will be translated
• UI text is dynamic or frequently changes
• Multiple elements share the same visible text

When to prefer text selectors:

• Single-language app with stable copy
• Readability and self-documentation are a priority
• Testing user-visible behavior exactly as it appears

In React Native, add testID props when using ID-based selectors:

<TouchableOpacity testID="submit-button" onPress={handleSubmit}>
  <Text>{t('submit')}</Text>
</TouchableOpacity>

testID Naming Convention

When using ID-based selectors:

{component}-{action/type}[-{variant}]

Examples:
- auth-prompt-login-button
- product-card-{id}
- otp-input-0
- tab-home
- dashboard-loading

2. Auth Pre-Flight Pattern

Prevent race conditions where Maestro interacts with the UI before auth state resolves. Add a zero-size auth-loaded marker that only renders when auth loading completes:

// In your tab bar or root layout
{!isLoading && <View testID="auth-loaded" style={{ width: 0, height: 0 }} />}

Then in every test:

- launchApp

# Prevent XCTest crash on cold boot (iOS)
- swipe:
    direction: DOWN
    duration: 100

# Wait for auth state to resolve
- extendedWaitUntil:
    visible:
      id: "auth-loaded"
    timeout: 15000

# Now safe to interact
- tapOn:
    id: "tab-home"

3. Adaptive Tests (Handle Both Auth States)

Tests should work regardless of whether the user is authenticated:

# Auth flow — only runs if login prompt is visible
- runFlow:
    when:
      visible: "Sign In"
    file: flows/auth-flow.yaml

# Already authenticated — proceed directly
- runFlow:
    when:
      visible:
        id: "tab-home"
    file: flows/authenticated-action.yaml

4. Testing Optimistic Updates

Use short timeouts to verify UI changes happen before server response:

# Trigger mutation
- tapOn:
    id: "action-button"

# OPTIMISTIC: UI must change within 3s (not waiting for server)
- extendedWaitUntil:
    visible:
      id: "undo-button"
    timeout: 3000

# Verify derived UI state
- extendedWaitUntil:
    visible:
      id: "user-indicator"
    timeout: 5000

Action	Expected Change	Timeout
Mutation trigger	Button state flips	< 3s
List update	Item appears/disappears	< 5s
Re-do action	Proves persistence	< 3s

5. Dismissing Native Alerts

React Native Alert.alert() creates native dialogs that block the UI:

- tapOn:
    id: "action-button"

# Wait for expected state change first
- extendedWaitUntil:
    visible:
      id: "new-state-element"
    timeout: 5000

# Dismiss alert (optional in case it already closed)
- tapOn:
    text: "OK"
    optional: true

# Brief delay for alert animation
- swipe:
    direction: DOWN
    duration: 300

6. Sub-Flows for Reusability

Break repeated sequences into sub-flow files:

.maestro/
├── flows/
│   ├── auth-and-return.yaml
│   ├── complete-purchase.yaml
│   └── verify-result.yaml
├── smoke-test.yaml
└── feature-test.yaml

# In main test
- runFlow:
    file: flows/auth-and-return.yaml

7. Deep Links (Expo)

Use the Expo scheme from app.json, not the bundle ID:

# WRONG
- openLink: "com.myapp://profile/settings"

# CORRECT
- openLink: "myapp://profile/settings"

Deep links must be registered in your app's deep link handler. Unregistered routes silently fail.

8. Platform-Specific Logic

- runFlow:
    when:
      platform: ios
    file: flows/ios-specific.yaml

- runFlow:
    when:
      platform: android
    file: flows/android-specific.yaml

9. Environment Variables

appId: com.myapp
env:
  TEST_EMAIL: maestro-test@example.com
  API_BASE_URL: http://localhost:3000
---
- inputText: ${TEST_EMAIL}

10. Selector State Properties

Use enabled, selected, checked, and focused to target elements by their current state. This is useful for validating interactive element states before or after actions.

# Only tap the submit button if it's enabled
- tapOn:
    id: "submit-button"
    enabled: true

# Assert a checkbox is checked
- assertVisible:
    id: "terms-checkbox"
    checked: true

# Wait for an input to be focused
- extendedWaitUntil:
    visible:
      id: "email-input"
      focused: true
    timeout: 3000

Property	Values	Use Case
enabled	true / false	Buttons that disable during submission or until form is valid
checked	true / false	Checkboxes, toggle switches
selected	true / false	Tab items, segmented controls
focused	true / false	Input fields with auto-focus

11. Relative Position Selectors

Distinguish between similar elements by their spatial relationship to other elements. This is more idiomatic and resilient than index-based selection.

# BAD — fragile, breaks if order changes
- tapOn:
    text: "Add to Basket"
    index: 1

# GOOD — contextual, self-documenting
- tapOn:
    text: "Add to Basket"
    below:
      text: "Awesome Shoes"

Available relative selectors:

# Target element below another
- tapOn:
    text: "Buy Now"
    below: "Product Title"

# Target element that is a child of a parent
- tapOn:
    text: "Delete"
    childOf:
      id: "item-card-42"

# Target a parent that contains a specific child
- tapOn:
    containsChild: "Urgent"

# Target by multiple descendants
- tapOn:
    containsDescendants:
      - id: title_id
        text: "Specific Title"
      - "Another descendant text"

# Horizontal positioning
- tapOn:
    text: "Edit"
    rightOf: "Username"

Selector	Meaning
below:	Element is positioned below the referenced element
above:	Element is positioned above the referenced element
leftOf:	Element is to the left of the referenced element
rightOf:	Element is to the right of the referenced element
childOf:	Element is a direct child of the referenced parent
containsChild:	Element contains a direct child matching the reference
containsDescendants:	Element contains all specified descendant elements

---

Authentication Testing

Architecture

Testing OTP or magic-link authentication in E2E requires capturing emails programmatically. The general pattern:

┌─────────────┐     ┌──────────────┐     ┌─────────────────┐
│  Maestro    │────▶│  Auth        │────▶│  Email Capture  │
│  Test       │     │  Provider    │     │  Service        │
└─────────────┘     └──────────────┘     └─────────────────┘
       │                                        │
       │         ┌──────────────────────────────┘
       │         ▼
       │   ┌─────────────┐
       └──▶│  REST API   │ ─── GET /api/v1/messages
           │  (email)    │ ─── Extract OTP code
           └─────────────┘

Common email capture services: Mailpit, MailHog, Ethereal.

OTP Fetch Script

Fetch OTP codes from your email capture service using Maestro's GraalJS runtime:

// CRITICAL: Maestro uses GraalJS — NO async/await, NO fetch()
var email = typeof EMAIL !== "undefined" ? EMAIL : "test@example.com";
var emailServiceUrl = typeof EMAIL_SERVICE_URL !== "undefined"
  ? EMAIL_SERVICE_URL : "http://localhost:8025";

var response = http.get(emailServiceUrl + "/api/v1/messages");
if (!response.ok) {
  throw new Error("Failed to fetch emails: " + response.status);
}

var data = json(response.body);
// Find the latest email and extract OTP code
var body = data.messages[0].Content.Body;
var match = body.match(/(\d{6})/);
output.OTP_CODE = match[1];

OTP Input Strategy

OTP components with auto-focus need individual digit entry. Tap each input before typing:

# Split OTP into digits via helper script
- runScript:
    file: scripts/split-otp.js
    env:
      OTP_CODE: ${output.OTP_CODE}

# Enter each digit by tapping its input
- tapOn:
    id: "otp-input-0"
- inputText: ${output.OTP_0}

- tapOn:
    id: "otp-input-1"
- inputText: ${output.OTP_1}
# ... repeat for all digits

For provider-specific implementations (Supabase + Mailpit, Firebase Auth, Auth0), create a project-level skill that extends this one.

---

GraalJS Script Rules

Maestro uses the GraalJS runtime. These constraints are non-negotiable:

Feature	Status
async/await	NOT supported
fetch()	NOT supported
http.get(), http.post()	Use these instead
json()	Use to parse response bodies
output.VAR	Set variables for use in YAML flow
var declarations	Required (use var, not const/let for safety)

// Script template
var response = http.get("http://localhost:8025/api/endpoint");
if (!response.ok) {
  throw new Error("Request failed: " + response.status);
}
var data = json(response.body);
output.RESULT = data.value;

---

Critical Gotchas

clearState Does NOT Clear iOS Keychain

clearState: true clears the app sandbox (UserDefaults, files, caches) but does NOT clear the iOS Keychain. Auth tokens stored via expo-secure-store (or any Keychain-based storage) persist across clearState resets and even app reinstalls.

# WRONG — user may still be authenticated
- launchApp:
    clearState: true
- assertVisible: "Welcome"  # Fails if Keychain has tokens

# CORRECT — wait for auth resolution, then adapt
- launchApp
- extendedWaitUntil:
    visible:
      id: "auth-loaded"
    timeout: 15000

Rules:

• Never rely on clearState to produce guest state on iOS
• For auth tests: skip clearState, use auth-loaded pre-flight
• For guest tests: use adaptive flows that handle both states
• Never assert guest-only UI after clearState

Note: On Android, clearState: true fully resets app data including credentials. This is an iOS-only gotcha.

XCTest kAXErrorInvalidUIElement Crash (iOS)

The XCTest driver may crash if Maestro interacts with the accessibility tree before the first render cycle completes on cold boot.

Fix: Add a no-op swipe immediately after launchApp:

- launchApp
- swipe:
    direction: DOWN
    duration: 100

API Server Dependency

Mobile apps calling backend APIs on localhost need either the full server or a mock server running. Without it, all API-dependent screens show loading spinners or empty states (queries fail silently).

Fix: Start a mock API server before running Maestro tests:

# Start mock server (serves canned responses on your API port)
npx tsx scripts/mock-api-server.ts &

# Then run tests
maestro test .maestro/my-test.yaml

Create a lightweight mock that returns canned JSON for each endpoint your app calls. This is faster and more deterministic than running your full backend.

Auth-Aware Tab Bars

Tab bars that show different tabs for guest vs authenticated users will cause selector failures:

State	Typical Tabs
Guest	home, search, cart, profile
Auth	home, feed, create, messages, profile

Only assert tabs that exist in both states, or use adaptive when: conditions.

---

Test File Template

# {Feature} {Action} Test
#
# Tests: {what this validates}
# Prerequisites:
# - Simulator/emulator running with app installed
# - Backend or mock server running (if API-dependent)

appId: com.myapp
env:
  TEST_EMAIL: maestro-{feature}@example.com
  EMAIL_SERVICE_URL: http://localhost:8025
---
# ==========================================
# STEP 1: LAUNCH + AUTH PRE-FLIGHT
# ==========================================

- launchApp

- swipe:
    direction: DOWN
    duration: 100

- extendedWaitUntil:
    visible:
      id: "auth-loaded"
    timeout: 15000

- takeScreenshot: 01-initial-state

# ==========================================
# STEP 2: {ACTION}
# ==========================================

- tapOn:
    id: "target-element"

# ==========================================
# STEP 3: VERIFY
# ==========================================

- extendedWaitUntil:
    visible:
      id: "expected-result"
    timeout: 5000

- takeScreenshot: 02-final-state

---

Folder Structure

.maestro/
├── README.md                    # Quick reference + testID inventory
├── config.yaml                  # Shared configuration
├── flows/                       # Reusable sub-flows
│   ├── auth-and-return.yaml
│   ├── complete-action.yaml
│   └── verify-result.yaml
├── scripts/                     # GraalJS helpers
│   ├── fetch-otp.js
│   └── split-otp.js
├── smoke-test.yaml              # Guest navigation
├── auth-signin.yaml             # OTP sign-in flow
├── feature-screenshots.yaml     # Screenshot capture flows
└── feature-action.yaml          # Feature-specific tests

scripts/
├── mock-api-server.ts           # Lightweight mock for E2E
└── run-e2e.sh                   # Orchestration script

Naming Conventions

Type	Pattern	Example
Main test	{feature}-{action}.yaml	checkout-purchase.yaml
Sub-flow	{action}-{context}.yaml	auth-and-return-to-dashboard.yaml
Script	{verb}-{noun}.js	fetch-otp.js

---

Infrastructure

Mock Server for API-Dependent Tests

Create a lightweight mock server that serves canned responses for your API layer. This is faster and more deterministic than running your full backend during E2E tests.

# Start mock server before running Maestro tests
npx tsx scripts/mock-api-server.ts &

Orchestration Script

Automate the full E2E setup with a shell script that:

1. Starts backend services (database, auth)
2. Seeds test data
3. Starts mock API server
4. Runs Maestro tests
5. Cleans up all services

bash scripts/run-e2e.sh

Seed Data

Tests that depend on specific data require seeded databases. Keep seed scripts alongside your test infrastructure and run them before each test suite.

---

Android-Specific Patterns

Emulator Setup

Android tests require an emulator or a USB-connected physical device. Maestro auto-detects connected devices.

# List available system images
sdkmanager --list | grep system-images

# Create emulator
avdmanager create avd -n maestro_test \
  -k "system-images;android-34;google_apis;arm64-v8a"

# Start emulator
emulator -avd maestro_test

iOS vs Android Differences

Aspect	iOS	Android
Device type	Simulator only (no physical)	Emulator + physical via ADB
clearState	Does NOT clear Keychain	Fully resets app data
Cold boot crash	XCTest kAXError (add swipe delay)	No equivalent issue
Performance	Runs natively (fast)	ARM emulation (slower on x86)
Permission dialogs	System alerts	System dialogs with different text

ADB Debugging

adb devices                                    # List connected devices
adb shell am start -n com.myapp/.MainActivity  # Launch app
adb logcat | grep Maestro                      # Filter Maestro logs
adb shell input keyevent 82                    # Unlock screen

Android Permission Handling

Android permissions appear as system dialogs. Dismiss with optional taps:

- tapOn:
    text: "Allow"
    optional: true

- tapOn:
    text: "While using the app"
    optional: true

---

CI/CD Integration

GitHub Actions with Maestro Cloud

Maestro Cloud provides real devices in CI without local simulators. Use the official action:

name: Mobile E2E Tests
on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  maestro-e2e:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      # Build Android APK
      - uses: actions/setup-java@v4
        with:
          java-version: '17'
          distribution: 'temurin'

      - name: Build Android APK
        run: |
          cd apps/mobile
          npx expo prebuild --platform android --no-install
          cd android && ./gradlew assembleRelease

      - name: Run Maestro Cloud Tests
        id: maestro
        uses: mobile-dev-inc/action-maestro-cloud@v2
        with:
          api-key: ${{ secrets.MAESTRO_API_KEY }}
          app-file: apps/mobile/android/app/build/outputs/apk/release/app-release.apk
          workspace: .maestro
          include-tags: ci

      # Access results
      # ${{ steps.maestro.outputs.MAESTRO_CLOUD_CONSOLE_URL }}
      # ${{ steps.maestro.outputs.MAESTRO_CLOUD_UPLOAD_STATUS }}
      # ${{ steps.maestro.outputs.MAESTRO_CLOUD_FLOW_RESULTS }}

Tag-Based Flow Filtering

Use tags to control which tests run in CI vs locally:

# In your flow file header
appId: com.myapp
tags:
  - ci
  - smoke
---
- launchApp
# ... test steps

# Run only CI-tagged flows locally
maestro test --include-tags ci .maestro/

# Exclude work-in-progress flows
maestro test --exclude-tags wip .maestro/

Local CI with Docker (Android Only)

FROM openjdk:17-slim

RUN curl -Ls "https://get.maestro.mobile.dev" | bash
ENV PATH="/root/.maestro/bin:${PATH}"

COPY .maestro/ /app/.maestro/
WORKDIR /app

CMD ["maestro", "test", ".maestro/"]

Note: iOS tests cannot run in Docker (requires macOS). Use Maestro Cloud for iOS in CI.

---

Maestro Cloud

Maestro Cloud runs tests on real devices without local simulator setup.

Setup

1. Create account at cloud.maestro.dev
2. Generate API key from dashboard
3. Store as MAESTRO_API_KEY secret in your CI provider

Running from CLI

# Upload and run on Maestro Cloud
maestro cloud --api-key $MAESTRO_API_KEY \
  --app-file ./app-release.apk \
  .maestro/

# With tag filtering
maestro cloud --api-key $MAESTRO_API_KEY \
  --app-file ./app-release.apk \
  --include-tags smoke \
  .maestro/

Key Points

• iOS testing: Supported on Maestro Cloud (not on local physical devices)
• Android testing: Both local physical devices and Maestro Cloud
• Results: Dashboard with video recordings, logs, and screenshots
• CI outputs: MAESTRO_CLOUD_CONSOLE_URL, MAESTRO_CLOUD_FLOW_RESULTS

---

Maestro MCP Server

The Maestro MCP server exposes Maestro's full command set as Model Context Protocol tools, letting AI agents execute tests and interact with devices directly — not just write YAML.

How It Complements This Skill

	This Skill	Maestro MCP
Role	Teaches correct patterns	Provides runtime execution
Layer	Authoring (write good YAML)	Execution (run, tap, assert, screenshot)
Output	Better test files	Live device interaction

Use both together: this skill ensures the AI writes correct tests; the MCP lets it run them immediately, see failures, and iterate.

Setup

The MCP ships with the Maestro CLI — no extra install needed:

# Verify it's available
maestro mcp

Claude Code — add to project .mcp.json or global settings:

{
  "mcpServers": {
    "maestro": {
      "command": "maestro",
      "args": ["mcp"]
    }
  }
}

Claude Desktop — add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS):

{
  "mcpServers": {
    "maestro": {
      "command": "maestro",
      "args": ["mcp"]
    }
  }
}

Also supported on Cursor, Windsurf, VS Code, and JetBrains IDEs. See the Maestro MCP docs for IDE-specific setup.

Key Capabilities

The MCP server exposes 47 tools organized by category:

Category	Tools	Examples
UI Interaction	tap, swipe, scroll, long press	tapOn, scrollUntilVisible
Text Input	type, erase, paste, copy	inputText, eraseText
Assertions	visibility, AI-powered	assertVisible, assertWithAI
App Lifecycle	launch, stop, clear state	launchApp, clearState
Device Control	location, orientation, airplane	setLocation, hideKeyboard
Flow Control	run flows, repeat, eval scripts	runFlow, evalScript
Media	screenshots, recording	takeScreenshot, startRecording
AI-Powered	visual assertions, defect detection	assertWithAI, assertNoDefectsWithAI

Write-Run-Fix Loop

With both this skill and the MCP active, the AI can:

1. Write a test YAML using patterns from this skill
2. Run it via MCP's runFlow / launchApp + interaction tools
3. See failures via screenshots and assertions
4. Fix the YAML and re-run — all in one conversation

---

Debugging

maestro test --debug .maestro/test.yaml   # Step through interactively
maestro record .maestro/test.yaml          # Record as video
maestro studio                             # Interactive UI builder
maestro hierarchy                          # View element tree

Screenshots saved to ~/.maestro/tests/{timestamp}/.

---

Checklist for New Tests

[ ] Unique test email (maestro-{feature}@example.com)
[ ] Selector strategy chosen (testID for i18n apps, text for single-language — see Pattern 1)
[ ] Selectors use state properties where relevant (enabled, checked — see Pattern 10)
[ ] Similar elements distinguished with relative selectors, not index (see Pattern 11)
[ ] Auth pre-flight pattern used (auth-loaded)
[ ] Post-launch swipe added (iOS crash prevention)
[ ] Both auth states handled (adaptive flows)
[ ] Native alerts dismissed after mutations
[ ] Short timeouts for optimistic updates (3-5s)
[ ] Sub-flows created for reusable sequences
[ ] Descriptive screenshots at key points
[ ] Header comment with prerequisites
[ ] Added to README.md test table
[ ] Mock API server started if backend-dependent
[ ] Tags added for CI filtering (ci, smoke, wip)

---

Common Errors

Error	Cause	Fix
"Unable to locate Java Runtime"	Java not in PATH	export JAVA_HOME=/opt/homebrew/opt/openjdk@17/...
"Element not found" after tap	Native alert blocking	Add tapOn: text: "OK" optional: true
OTP digits not entering	Auto-focus interference	Use individual otp-input-N testIDs
Test passes but nothing happened	optional: true misused	Only use optional for truly optional actions
"Assertion is false" on visibility	Element not rendered yet	Increase timeout or verify testID exists
Script output empty	Wrong JS API	Use http.get() not fetch()
Auth state inconsistent after clearState	iOS Keychain not cleared	Don't use clearState, use adaptive flows
kAXErrorInvalidUIElement crash	Cold boot race (iOS)	Add post-launch swipe delay
Loading spinners / empty screens	No API server running	Start mock API server before tests
Permission dialog blocking (Android)	System dialog not dismissed	Add tapOn: text: "Allow" optional: true

---

Resources

• Maestro Documentation
• Maestro Selectors Reference
• Maestro Cloud
• Maestro MCP Server
• Maestro GitHub
• GraalJS HTTP Requests
• Conditions & Adaptive Flows
• GitHub Actions Integration
• BrowserStack: Maestro Testing Guide
• DEV.to: Tips & Tricks for Maestro + React Native