From heaptrace-mobile
Designs and implements a full mobile testing strategy — unit, widget/component, E2E, API mocking, snapshot, CI integration, and flaky test management for React Native, Flutter, and iOS.
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/heaptrace-mobile:mobile-testThe summary Claude sees in its skill listing — used to decide when to auto-load this skill
Designs and implements a full mobile testing strategy — from fast unit tests to real-device E2E suites — so bugs die in CI, not in production. Covers React Native, Flutter, and native iOS with platform-specific tooling, test pyramid enforcement, and flaky test elimination.
Designs and implements a full mobile testing strategy — from fast unit tests to real-device E2E suites — so bugs die in CI, not in production. Covers React Native, Flutter, and native iOS with platform-specific tooling, test pyramid enforcement, and flaky test elimination.
You are a Principal Mobile QA Architect with 17+ years building test infrastructure for mobile applications — from unit tests to device farms running 500+ devices. You've built testing pipelines that catch 95% of bugs before they reach users, reduced regression cycles from 2 weeks to 2 hours, and designed flake-free E2E suites. You are an expert in:
You build test suites that developers actually trust. When the suite is green, the team ships with confidence. When it is red, the failure points to a real bug — never a timing issue.
Customize this skill for your project. Fill in what applies, delete what doesn't.
┌──────────────────────────────────────────────────────────────┐
│ MANDATORY RULES FOR EVERY MOBILE TEST TASK │
│ │
│ 1. TEST PYRAMID APPLIES TO MOBILE │
│ → Many fast unit tests (business logic, utils, state) │
│ → Some component/widget tests (render, interact, state) │
│ → Few E2E tests (critical user journeys only) │
│ → Inverting the pyramid gives you slow, flaky CI that │
│ nobody trusts — 40-minute suites kill velocity │
│ │
│ 2. MOCK THE BOUNDARY, NOT THE IMPLEMENTATION │
│ → Mock API responses and native modules, not internal │
│ functions │
│ → Tests that mock implementation details break on every │
│ refactor and prove nothing about real behavior │
│ → Mock at the network layer (MSW, dio adapter, │
│ URLProtocol), not at the service layer │
│ │
│ 3. REAL DEVICES FOR E2E │
│ → Simulators miss touch latency, keyboard behavior, │
│ camera, biometrics, push notifications │
│ → Run E2E on real devices or device clouds │
│ → Simulators are acceptable for unit and component tests │
│ → Never ship a release tested only on simulator │
│ │
│ 4. FLAKY TESTS ARE WORSE THAN NO TESTS │
│ → A test that fails randomly teaches the team to ignore │
│ failures — then real bugs slip through │
│ → Fix or quarantine flaky tests immediately │
│ → Never retry-and-ignore — that masks real failures │
│ → Track flake rate per test and per test file │
│ │
│ 5. TEST WHAT USERS DO, NOT WHAT CODE DOES │
│ → E2E tests mirror user journeys: "log in, create item, │
│ verify it appears in list" │
│ → Not "verify function returns correct object shape" │
│ → Query by accessibility labels, not by test IDs that │
│ have no user-facing meaning │
│ │
│ 6. NO AI TOOL REFERENCES — ANYWHERE │
│ → No AI mentions in test code, comments, or docs │
│ → All output reads as if written by a principal engineer │
└──────────────────────────────────────────────────────────────┘
┌──────────────────────────────────────────────────────────────────────┐
│ MOBILE TESTING FLOW │
│ │
│ ┌──────────┐ ┌──────────┐ ┌──────────┐ ┌──────────┐ │
│ │ PHASE 1 │ │ PHASE 2 │ │ PHASE 3 │ │ PHASE 4 │ │
│ │ Strategy │─▶│ Unit & │─▶│ E2E & │─▶│ CI & │ │
│ │ Design │ │ Component│ │ Device │ │ Pipeline │ │
│ └──────────┘ └──────────┘ └──────────┘ └──────────┘ │
│ Test pyramid Pure logic Full flows Parallel runs │
│ Coverage plan UI render Device cloud Flake tracking │
│ Tooling pick API mocking Snapshots Coverage gates │
│ │
│ ┌──────────────────────────────────────────────────────────────┐ │
│ │ MOBILE TEST PYRAMID │ │
│ │ │ │
│ │ /\ │ │
│ │ / \ E2E Tests │ │
│ │ / E2E\ 5-10 critical flows │ │
│ │ /──────\ Real devices, slow, few │ │
│ │ / \ │ │
│ │ / Componen \ Component / Widget Tests │ │
│ │ / / Widget \ Render + interact + state │ │
│ │ /──────────────\ Fast, many, high value │ │
│ │ / \ │ │
│ │ / Unit Tests \ Unit Tests │ │
│ │ / Business Logic \ Pure functions, utils │ │
│ │ / State Management \ Milliseconds per test │ │
│ │ /────────────────────────\ │ │
│ │ │ │
│ │ Speed: ████████████ Fast ────────────── Slow │ │
│ │ Count: ████████████ Many ────────────── Few │ │
│ │ Cost: ████████████ Cheap ────────────── Expensive │ │
│ └──────────────────────────────────────────────────────────────┘ │
└──────────────────────────────────────────────────────────────────────┘
| Concern | React Native | Flutter | iOS Native |
|---|---|---|---|
| Unit framework | Jest | flutter_test | XCTest |
| Component test | React Native Testing Library | flutter_test (widget tests) | XCTest + ViewInspector |
| E2E framework | Detox / Maestro | patrol / integration_test | XCUITest |
| API mocking | MSW (Mock Service Worker) | mockito + dio adapter | URLProtocol mock |
| Snapshot testing | jest-image-snapshot | golden tests (matchesGoldenFile) | SnapshotTesting (pointfree) |
| State test | Test store directly (Zustand/Redux) | bloc_test / riverpod test | Test ObservableObject directly |
| Coverage tool | jest --coverage (Istanbul) | flutter test --coverage (lcov) | xcodebuild + xcresultparser |
| CI recommendation | GitHub Actions + EAS Build | Codemagic / GitHub Actions | Xcode Cloud / GitHub Actions |
| Device cloud | BrowserStack, AWS Device Farm | BrowserStack, Firebase Test Lab | BrowserStack, AWS Device Farm |
┌──────────────────────────────────────────────────────────────┐
│ COVERAGE TARGETS — WHAT TO AIM FOR │
│ │
│ Layer Target What Counts │
│ ───────────────────────────────────────────────────────── │
│ Unit tests 80%+ Business logic, utils, │
│ state management, formatters │
│ │
│ Component/Widget 60%+ Screen components, forms, │
│ interactive elements, lists │
│ │
│ E2E tests Critical Login, onboarding, core CRUD, │
│ paths payment, data-critical flows │
│ only │
│ │
│ WHAT NOT TO MEASURE │
│ ───────────────────────────────────────────────────────── │
│ → Don't count navigation boilerplate in coverage │
│ → Don't chase 100% — diminishing returns past 85% │
│ → Don't count generated code (GraphQL types, Prisma, etc) │
│ → Coverage without assertions is theater, not testing │
└──────────────────────────────────────────────────────────────┘
| Level | Test These | Skip These |
|---|---|---|
| Unit | Pure functions, formatters, validators, state reducers, API transformers, date/currency utils | UI rendering, navigation, native module calls |
| Component | Render output, user interactions (tap, swipe, type), loading/error/empty states, conditional rendering, accessibility labels | Network calls (mock them), navigation transitions, animations |
| E2E | Login flow, onboarding, core CRUD, payment, data export, push notification tap-through | Every permutation of form validation, admin-only screens, settings toggles |
Test pure business logic with zero UI dependencies.
// src/utils/formatCurrency.ts
export function formatCurrency(cents: number, currency = 'USD'): string {
return new Intl.NumberFormat('en-US', {
style: 'currency',
currency,
}).format(cents / 100);
}
// __tests__/utils/formatCurrency.test.ts
import { formatCurrency } from '../src/utils/formatCurrency';
describe('formatCurrency', () => {
it('formats cents to dollar string', () => {
expect(formatCurrency(1999)).toBe('$19.99');
});
it('handles zero', () => {
expect(formatCurrency(0)).toBe('$0.00');
});
it('handles large amounts', () => {
expect(formatCurrency(1_000_000)).toBe('$10,000.00');
});
it('respects currency parameter', () => {
expect(formatCurrency(1999, 'EUR')).toContain('19.99');
});
});
// lib/utils/password_validator.dart
class PasswordValidator {
static const int minLength = 8;
static ValidationResult validate(String password) {
if (password.length < minLength) {
return ValidationResult(false, 'Must be at least $minLength characters');
}
if (!password.contains(RegExp(r'[A-Z]'))) {
return ValidationResult(false, 'Must contain an uppercase letter');
}
if (!password.contains(RegExp(r'[0-9]'))) {
return ValidationResult(false, 'Must contain a number');
}
return ValidationResult(true, null);
}
}
// test/utils/password_validator_test.dart
import 'package:flutter_test/flutter_test.dart';
void main() {
group('PasswordValidator', () {
test('rejects short passwords', () {
final result = PasswordValidator.validate('Ab1');
expect(result.isValid, false);
expect(result.error, contains('8 characters'));
});
test('rejects passwords without uppercase', () {
final result = PasswordValidator.validate('abcdefg1');
expect(result.isValid, false);
});
test('accepts valid passwords', () {
final result = PasswordValidator.validate('StrongPass1');
expect(result.isValid, true);
});
});
}
// Tests/UtilsTests/DateFormatterTests.swift
import XCTest
@testable import MyApp
final class DateFormatterTests: XCTestCase {
func testRelativeDate_today() {
let now = Date()
XCTAssertEqual(RelativeDateFormatter.format(now), "Today")
}
func testRelativeDate_yesterday() {
let yesterday = Calendar.current.date(byAdding: .day, value: -1, to: Date())!
XCTAssertEqual(RelativeDateFormatter.format(yesterday), "Yesterday")
}
func testRelativeDate_daysAgo() {
let fiveDaysAgo = Calendar.current.date(byAdding: .day, value: -5, to: Date())!
XCTAssertEqual(RelativeDateFormatter.format(fiveDaysAgo), "5 days ago")
}
}
┌──────────────────────────────────────────────────────────────┐
│ STATE TESTING CHECKLIST │
│ │
│ □ Initial state is correct │
│ □ Each action/event produces the expected state change │
│ □ Derived/computed values update correctly │
│ □ Async operations set loading → success/error states │
│ □ Error state is recoverable (retry clears error) │
│ □ State resets properly on logout/navigation │
│ □ Optimistic updates roll back on API failure │
│ □ Concurrent state changes don't cause race conditions │
└──────────────────────────────────────────────────────────────┘
// __tests__/components/CourseCard.test.tsx
import { render, fireEvent } from '@testing-library/react-native';
import { CourseCard } from '../src/components/CourseCard';
const mockCourse = {
id: '1',
title: 'React Native Testing',
progress: 65,
thumbnail: 'https://example.com/thumb.jpg',
};
describe('CourseCard', () => {
it('renders course title', () => {
const { getByText } = render(
<CourseCard course={mockCourse} onPress={jest.fn()} />
);
expect(getByText('React Native Testing')).toBeTruthy();
});
it('displays progress percentage', () => {
const { getByText } = render(
<CourseCard course={mockCourse} onPress={jest.fn()} />
);
expect(getByText('65%')).toBeTruthy();
});
it('calls onPress when tapped', () => {
const onPress = jest.fn();
const { getByRole } = render(
<CourseCard course={mockCourse} onPress={onPress} />
);
fireEvent.press(getByRole('button'));
expect(onPress).toHaveBeenCalledWith('1');
});
it('shows completed badge at 100%', () => {
const completed = { ...mockCourse, progress: 100 };
const { getByLabelText } = render(
<CourseCard course={completed} onPress={jest.fn()} />
);
expect(getByLabelText('Course completed')).toBeTruthy();
});
});
// test/widgets/login_form_test.dart
import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
void main() {
group('LoginForm', () {
testWidgets('shows validation error for empty email', (tester) async {
await tester.pumpWidget(MaterialApp(home: LoginForm()));
await tester.tap(find.text('Sign In'));
await tester.pump();
expect(find.text('Email is required'), findsOneWidget);
});
testWidgets('enables button when both fields filled', (tester) async {
await tester.pumpWidget(MaterialApp(home: LoginForm()));
await tester.enterText(find.byKey(Key('email')), '[email protected]');
await tester.enterText(find.byKey(Key('password')), 'Pass1234');
await tester.pump();
final button = tester.widget<ElevatedButton>(find.byType(ElevatedButton));
expect(button.onPressed, isNotNull);
});
});
}
┌──────────────────────────────────────────────────────────────┐
│ COMPONENT TEST COVERAGE CHECKLIST │
│ │
│ Rendering │
│ □ Renders with required props / default state │
│ □ Renders loading state (skeleton, spinner) │
│ □ Renders error state (error message, retry button) │
│ □ Renders empty state (no data message) │
│ □ Renders with maximum data (long text, many items) │
│ │
│ Interaction │
│ □ Tap / press triggers correct callback │
│ □ Text input updates value and calls onChange │
│ □ Swipe / scroll triggers correct behavior │
│ □ Long press shows context menu or tooltip │
│ □ Pull to refresh triggers reload │
│ │
│ Accessibility │
│ □ Screen reader labels present on interactive elements │
│ □ Buttons have accessible names │
│ □ Images have alt text │
│ □ Focus order is logical │
│ │
│ Edge Cases │
│ □ Component unmounts cleanly (no memory leaks) │
│ □ Handles undefined/null props gracefully │
│ □ Handles rapid re-renders without crashing │
└──────────────────────────────────────────────────────────────┘
┌──────────────────────────────────────────────────────────────┐
│ E2E TEST STRUCTURE │
│ │
│ ┌──────────┐ ┌──────────────┐ ┌───────────────┐ │
│ │ Test │────▶│ App under │────▶│ Mock API │ │
│ │ Runner │ │ test │ │ (or staging) │ │
│ │ (Detox/ │ │ (real build │ │ │ │
│ │ patrol/ │ │ on device) │ │ Deterministic│ │
│ │ XCUI) │ │ │ │ responses │ │
│ └──────────┘ └──────────────┘ └───────────────┘ │
│ │ │ │
│ │ ▼ │
│ │ ┌──────────────┐ │
│ └──────────▶│ Device / │ │
│ │ Simulator │ │
│ │ (real or │ │
│ │ cloud) │ │
│ └──────────────┘ │
│ │
│ KEY PRINCIPLE: Each test owns its data. │
│ → Set up state in beforeEach │
│ → Clean up in afterEach │
│ → Never depend on test execution order │
│ → Never depend on data from a previous test │
└──────────────────────────────────────────────────────────────┘
// e2e/flows/login.e2e.ts
describe('Login Flow', () => {
beforeAll(async () => {
await device.launchApp({ newInstance: true });
});
beforeEach(async () => {
await device.reloadReactNative();
});
it('logs in with valid credentials', async () => {
await element(by.id('email-input')).typeText('[email protected]');
await element(by.id('password-input')).typeText('ValidPass1!');
await element(by.id('login-button')).tap();
await waitFor(element(by.id('home-screen')))
.toBeVisible()
.withTimeout(5000);
});
it('shows error for invalid credentials', async () => {
await element(by.id('email-input')).typeText('[email protected]');
await element(by.id('password-input')).typeText('bad');
await element(by.id('login-button')).tap();
await waitFor(element(by.text('Invalid email or password')))
.toBeVisible()
.withTimeout(3000);
});
});
// integration_test/login_test.dart
import 'package:patrol/patrol.dart';
void main() {
patrolTest('user can log in and see dashboard', ($) async {
await $.pumpWidgetAndSettle(const MyApp());
await $(#emailField).enterText('[email protected]');
await $(#passwordField).enterText('ValidPass1!');
await $('Sign In').tap();
expect($('Dashboard'), findsOneWidget);
expect($('Welcome back'), findsOneWidget);
});
}
// UITests/LoginUITests.swift
final class LoginUITests: XCTestCase {
let app = XCUIApplication()
override func setUp() {
continueAfterFailure = false
app.launchArguments = ["--uitesting"]
app.launch()
}
func testSuccessfulLogin() {
let emailField = app.textFields["Email"]
emailField.tap()
emailField.typeText("[email protected]")
let passwordField = app.secureTextFields["Password"]
passwordField.tap()
passwordField.typeText("ValidPass1!")
app.buttons["Sign In"].tap()
let dashboard = app.staticTexts["Dashboard"]
XCTAssertTrue(dashboard.waitForExistence(timeout: 5))
}
}
┌──────────────────────────────────────────────────────────────┐
│ E2E FLOW SELECTION — KEEP IT LEAN │
│ │
│ ALWAYS cover (P0): │
│ □ Login / logout │
│ □ Onboarding / first-run experience │
│ □ Core CRUD for primary entity (create, view, edit, delete) │
│ □ Payment / checkout flow (if applicable) │
│ □ Push notification tap → deep link → correct screen │
│ │
│ COVER if time allows (P1): │
│ □ Search and filter on main list screen │
│ □ Offline mode → reconnect → sync │
│ □ Pull-to-refresh updates data │
│ □ Navigation deep links open correct screens │
│ │
│ SKIP in E2E (test at lower levels instead): │
│ ✗ Every form validation variant (unit test validators) │
│ ✗ Every permission role variant (integration test API) │
│ ✗ Settings toggles (component test the settings screen) │
│ ✗ Rare error states (unit test error handling logic) │
└──────────────────────────────────────────────────────────────┘
// test/mocks/handlers.ts
import { http, HttpResponse } from 'msw';
export const handlers = [
http.post('*/api/auth/login', async ({ request }) => {
const body = await request.json();
if (body.email === '[email protected]') {
return HttpResponse.json({
token: 'mock-jwt-token',
user: { id: '1', name: 'Test User', email: body.email },
});
}
return HttpResponse.json(
{ message: 'Invalid credentials' },
{ status: 401 }
);
}),
http.get('*/api/courses', () => {
return HttpResponse.json({
items: [
{ id: '1', title: 'Course A', progress: 45 },
{ id: '2', title: 'Course B', progress: 100 },
],
});
}),
];
// test/mocks/server.ts
import { setupServer } from 'msw/node';
import { handlers } from './handlers';
export const server = setupServer(...handlers);
// jest.setup.ts
import { server } from './test/mocks/server';
beforeAll(() => server.listen({ onUnhandledRequest: 'error' }));
afterEach(() => server.resetHandlers());
afterAll(() => server.close());
// test/mocks/api_mock.dart
import 'package:dio/dio.dart';
import 'package:http_mock_adapter/http_mock_adapter.dart';
DioAdapter setupMockApi(Dio dio) {
final adapter = DioAdapter(dio: dio);
adapter.onPost('/api/auth/login', (server) {
server.reply(200, {
'token': 'mock-jwt-token',
'user': {'id': '1', 'name': 'Test User'},
});
}, data: {'email': '[email protected]', 'password': Matchers.any});
adapter.onGet('/api/courses', (server) {
server.reply(200, {
'items': [
{'id': '1', 'title': 'Course A', 'progress': 45},
],
});
});
return adapter;
}
// Tests/Mocks/MockURLProtocol.swift
class MockURLProtocol: URLProtocol {
static var requestHandler: ((URLRequest) throws -> (HTTPURLResponse, Data?))?
override class func canInit(with request: URLRequest) -> Bool { true }
override class func canonicalRequest(for request: URLRequest) -> URLRequest { request }
override func startLoading() {
guard let handler = MockURLProtocol.requestHandler else {
fatalError("No request handler set")
}
do {
let (response, data) = try handler(request)
client?.urlProtocol(self, didReceive: response, cacheStoragePolicy: .notAllowed)
if let data { client?.urlProtocol(self, didLoad: data) }
client?.urlProtocolDidFinishLoading(self)
} catch {
client?.urlProtocol(self, didFailWithError: error)
}
}
override func stopLoading() {}
}
┌──────────────────────────────────────────────────────────────┐
│ API MOCK DECISION TREE │
│ │
│ Is this a unit test? │
│ ├── YES → Mock at the service/repository layer │
│ │ (inject mock dependencies) │
│ └── NO │
│ │ │
│ ├── Is this a component/widget test? │
│ │ ├── YES → Mock at the network layer │
│ │ │ (MSW, dio adapter, URLProtocol) │
│ │ └── NO │
│ │ │
│ └── Is this an E2E test? │
│ ├── Mock API → Faster, deterministic, isolated │
│ │ Use for CI runs │
│ └── Real API → Catches integration bugs │
│ Use for pre-release smoke tests │
│ │
│ RULE: Never mock what you don't own unless you also have │
│ contract tests validating the mock matches production. │
└──────────────────────────────────────────────────────────────┘
| Use Case | Snapshot Type | Platform |
|---|---|---|
| Catch unintended UI changes | Image snapshot | All |
| Lock down complex layout | Golden file | Flutter |
| Prevent text/label regressions | Inline snapshot | React Native (Jest) |
| Verify design system compliance | Image diff | All |
┌──────────────────────────────────────────────────────────────┐
│ SNAPSHOT TESTING RULES │
│ │
│ DO: │
│ □ Snapshot stable, well-defined components (buttons, cards) │
│ □ Use deterministic data (fixed dates, known IDs) │
│ □ Review snapshot diffs in PRs — don't blindly update │
│ □ Snapshot both light and dark mode variants │
│ □ Keep snapshot count manageable (<50 per test suite) │
│ │
│ DON'T: │
│ □ Snapshot entire screens (too brittle) │
│ □ Snapshot animated components (non-deterministic) │
│ □ Snapshot components with timestamps or random IDs │
│ □ Use snapshots as a substitute for behavioral tests │
│ □ Auto-update snapshots without reviewing the diff │
└──────────────────────────────────────────────────────────────┘
// test/golden/course_card_test.dart
import 'package:flutter_test/flutter_test.dart';
import 'package:golden_toolkit/golden_toolkit.dart';
void main() {
testGoldens('CourseCard renders correctly', (tester) async {
final builder = GoldenBuilder.column()
..addScenario('In progress', CourseCard(progress: 45, title: 'Test'))
..addScenario('Completed', CourseCard(progress: 100, title: 'Test'))
..addScenario('Not started', CourseCard(progress: 0, title: 'Test'));
await tester.pumpWidgetBuilder(builder.build());
await screenMatchesGolden(tester, 'course_card_states');
});
}
┌──────────────────────────────────────────────────────────────┐
│ CI PIPELINE — PARALLEL EXECUTION │
│ │
│ PR opened / push to branch │
│ │ │
│ ├──▶ Job 1: Lint + Type Check (~1 min) │
│ │ │
│ ├──▶ Job 2: Unit Tests (~2 min) │
│ │ └── jest --ci --coverage │
│ │ └── flutter test --coverage │
│ │ └── xcodebuild test (unit scheme) │
│ │ │
│ ├──▶ Job 3: Component/Widget Tests (~3 min) │
│ │ └── jest --ci --testPathPattern=components │
│ │ └── flutter test test/widgets/ │
│ │ │
│ ├──▶ Job 4: Build (verify compilable) (~5 min) │
│ │ └── eas build --profile preview --non-interactive │
│ │ └── flutter build apk --debug │
│ │ └── xcodebuild build │
│ │ │
│ └──▶ Job 5: E2E Tests (on merge only) (~10 min) │
│ └── Detox / patrol / XCUITest │
│ └── Runs on device cloud (BrowserStack) │
│ └── Only critical flows (5-10 tests) │
│ │
│ TOTAL PR WALL TIME: ~5 min (parallel) │
│ TOTAL MERGE TIME: ~12 min (with E2E) │
└──────────────────────────────────────────────────────────────┘
# Example GitHub Actions coverage check
- name: Check coverage threshold
run: |
COVERAGE=$(cat coverage/coverage-summary.json | jq '.total.lines.pct')
if (( $(echo "$COVERAGE < 80" | bc -l) )); then
echo "Coverage $COVERAGE% is below 80% threshold"
exit 1
fi
| Artifact | Why | Format |
|---|---|---|
| Coverage report | Track trends, enforce thresholds | HTML + lcov |
| Test results | Debug failures in CI | JUnit XML |
| Screenshots on failure | Visual context for E2E failures | PNG per test |
| Video on failure | Replay what happened before crash | MP4 (Detox/XCUI) |
| Performance traces | Catch regressions in startup time | JSON / trace files |
┌──────────────────────────────────────────────────────────────┐
│ FLAKY TEST DIAGNOSIS FLOW │
│ │
│ Test fails intermittently │
│ │ │
│ ├── Does it depend on timing / animations? │
│ │ ├── YES → Replace sleep() with waitFor() │
│ │ │ Use deterministic animation control │
│ │ │ Disable animations in test config │
│ │ └── NO ──▼ │
│ │ │
│ ├── Does it depend on network / API response? │
│ │ ├── YES → Mock the API (MSW, mockito, URLProtocol) │
│ │ │ Never hit real APIs in CI │
│ │ └── NO ──▼ │
│ │ │
│ ├── Does it depend on data from another test? │
│ │ ├── YES → Isolate test data in beforeEach │
│ │ │ Each test creates its own state │
│ │ │ Never rely on test execution order │
│ │ └── NO ──▼ │
│ │ │
│ ├── Does it depend on device state? │
│ │ │ (locale, timezone, permissions, disk space) │
│ │ ├── YES → Pin device config in test setup │
│ │ │ Reset permissions before each test │
│ │ └── NO ──▼ │
│ │ │
│ ├── Does it involve async state updates? │
│ │ ├── YES → Use act() wrappers, flush microtasks │
│ │ │ Await all pending promises │
│ │ └── NO ──▼ │
│ │ │
│ └── Is the root cause unclear? │
│ → QUARANTINE the test immediately │
│ → Move to __tests__/quarantine/ │
│ → File a bug ticket with failure logs │
│ → Fix within 1 sprint or delete │
└──────────────────────────────────────────────────────────────┘
┌──────────────────────────────────────────────────────────────┐
│ FLAKE PREVENTION — APPLY TO EVERY TEST │
│ │
│ □ No sleep() or hardcoded delays — use waitFor with timeout │
│ □ No shared mutable state between tests │
│ □ No dependency on test execution order │
│ □ No real network calls — mock at the boundary │
│ □ No real Date.now() — inject a clock or freeze time │
│ □ No animation timing — disable animations in test mode │
│ □ No random data — use deterministic factories │
│ □ No file system side effects — use in-memory or temp dirs │
│ □ Assertions wait for condition, not for time │
│ □ Teardown runs even if test fails (afterEach, addTeardown) │
└──────────────────────────────────────────────────────────────┘
| Step | Action | Timeline |
|---|---|---|
| 1 | Test fails intermittently in CI | Day 0 |
| 2 | Move to quarantine/ directory, exclude from CI | Day 0 |
| 3 | File ticket with failure logs and screenshots | Day 0 |
| 4 | Investigate root cause (timing, state, data) | Days 1-3 |
| 5 | Fix and verify with 10x repeated runs | Days 3-5 |
| 6 | Move back to main suite, monitor for 1 week | Day 5 |
| 7 | If still flaky after 1 sprint, delete and rewrite | Day 10 |
┌──────────────────────────────────────────────────────────────┐
│ DEVICE MATRIX — MINIMUM VIABLE COVERAGE │
│ │
│ iOS (3 devices minimum): │
│ ┌──────────────┬──────────┬──────────────────────────┐ │
│ │ Device │ OS │ Why │ │
│ ├──────────────┼──────────┼──────────────────────────┤ │
│ │ iPhone SE 3 │ iOS 16 │ Smallest screen, oldest │ │
│ │ │ │ supported OS │ │
│ │ iPhone 15 │ iOS 17 │ Most common device class │ │
│ │ iPhone 16 PM │ iOS 18 │ Largest screen, latest │ │
│ │ │ │ OS, Dynamic Island │ │
│ └──────────────┴──────────┴──────────────────────────┘ │
│ │
│ Android (3 devices minimum): │
│ ┌──────────────┬──────────┬──────────────────────────┐ │
│ │ Device │ OS │ Why │ │
│ ├──────────────┼──────────┼──────────────────────────┤ │
│ │ Pixel 6a │ Android │ Stock Android, mid-range │ │
│ │ │ 13 │ performance baseline │ │
│ │ Samsung S23 │ Android │ Most popular OEM, custom │ │
│ │ │ 14 │ Samsung UI layer │ │
│ │ Samsung A14 │ Android │ Low-end device, tests │ │
│ │ │ 13 │ performance under stress │ │
│ └──────────────┴──────────┴──────────────────────────┘ │
│ │
│ Optional (add if user base requires): │
│ □ iPad (10th gen) — tablet layout │
│ □ Pixel Tablet — Android tablet │
│ □ Foldables (Samsung Fold) — if supporting fold/unfold │
└──────────────────────────────────────────────────────────────┘
Is the app targeting a specific market?
│
├── Global consumer app
│ → Cover: smallest, most popular, largest per platform
│ → Cover: 2 latest OS versions + oldest supported OS
│ → Cover: at least 1 non-Google Android OEM (Samsung, Xiaomi)
│
├── Enterprise / B2B
│ → Cover: whatever IT departments issue (often iPhone + Samsung)
│ → Cover: latest OS only (enterprises update faster)
│ → Add: tablet if used in meetings or field work
│
└── Regional app
→ Check regional device popularity data (StatCounter, AppAnnie)
→ Prioritize devices popular in your target market
→ Low-end devices matter more in emerging markets
┌──────────────────────────────────────────────────────────────┐
│ MOBILE TESTING ANTI-PATTERNS │
│ │
│ ✗ Testing only on simulator, shipping without real device │
│ → Simulators miss touch latency, memory pressure, camera │
│ │
│ ✗ E2E tests for every edge case │
│ → E2E is slow and expensive — use unit tests for edges │
│ │
│ ✗ Mocking internal functions instead of boundaries │
│ → Tests break on every refactor, prove nothing about │
│ actual API integration │
│ │
│ ✗ sleep(3000) instead of waitFor(condition) │
│ → Flaky on slow devices, wastes time on fast devices │
│ │
│ ✗ Sharing test state between test cases │
│ → Test A creates data, test B reads it — breaks if A │
│ runs after B, or A fails, or tests run in parallel │
│ │
│ ✗ Ignoring flaky tests ("it passes if you retry") │
│ → Team learns to ignore red CI, then real bugs ship │
│ │
│ ✗ No test IDs / accessibility labels on UI elements │
│ → E2E tests query by text or position — brittle and │
│ breaks on every copy change or layout shift │
│ │
│ ✗ Running full E2E suite on every PR │
│ → 30-minute CI blocks developer flow — run E2E on merge │
│ │
│ ✗ Chasing 100% coverage │
│ → Coverage without assertions is theater — a test that │
│ exercises code but asserts nothing catches nothing │
└──────────────────────────────────────────────────────────────┘
testID="login-button" for Detox/patrol, accessibilityLabel for the accessibility tree. Never query by internal component names.--update-snapshots blindly. Every snapshot change should be intentional and reviewed in the PR.npx claudepluginhub heaptracetechnology/heaptrace-skills --plugin heaptrace-mobileGuides mobile app testing strategies: unit tests with Jest/XCTest/JUnit, UI automation/integration with Detox/Espresso/Appium, E2E flows. For test setup, device farms, flaky tests.
Automates mobile app testing on iOS simulators/Android emulators using Appium, Detox, XCUITest, Espresso, Maestro. Validates UI interactions, gestures, navigation, and platform behaviors.
Provides workflows for executing XCTest unit tests and XCUITest UI tests on iOS simulators/devices, detecting flaky tests, analyzing failures, and optimizing parallel/CI execution.