Jest Setup for Expo

jest-expo gives Expo SDK 57 projects a working Jest preset: native modules are mocked, TypeScript transforms are configured, and you can run unit and component tests on every commit without booting a simulator.

Recipe

Quick-reference recipe card - copy-paste ready.

npx expo install jest-expo jest @types/jest @testing-library/react-native test-renderer --dev

{
  "scripts": {
    "test": "jest --watchAll",
    "test:ci": "jest --ci --coverage=false"
  },
  "jest": {
    "preset": "jest-expo",
    "transformIgnorePatterns": [
      "node_modules/(?!((jest-)?react-native|@react-native(-community)?)|expo(nent)?|@expo(nent)?/.*|@expo-google-fonts/.*|react-navigation|@react-navigation/.*|@sentry/react-native|native-base|react-native-svg)"
    ],
    "setupFilesAfterEnv": ["<rootDir>/jest.setup.ts"]
  }
}

// jest.setup.ts
import "@testing-library/react-native";
 
afterEach(() => {
  jest.clearAllMocks();
});

When to reach for this:

• Every Expo app that ships features - run tests in CI before EAS builds.
• Component and hook tests with @testing-library/react-native (see React Native Testing Library).
• Pure TypeScript utilities (formatters, reducers, API mappers) with no native imports.
• Snapshot tests for small, stable presentational components - not navigation trees.

Working Example

# From project root (Expo SDK 57)
npx expo install jest-expo jest @types/jest @testing-library/react-native test-renderer --dev

// package.json (excerpt)
{
  "scripts": {
    "test": "jest --watchAll",
    "test:ci": "jest --ci --coverage=false --changedSince=origin/main",
    "test:update-snapshots": "jest -u --coverage=false"
  },
  "jest": {
    "preset": "jest-expo",
    "transformIgnorePatterns": [
      "node_modules/(?!((jest-)?react-native|@react-native(-community)?)|expo(nent)?|@expo(nent)?/.*|@expo-google-fonts/.*|react-navigation|@react-navigation/.*|@sentry/react-native|native-base|react-native-svg)"
    ],
    "setupFilesAfterEnv": ["<rootDir>/jest.setup.ts"],
    "collectCoverageFrom": [
      "**/*.{ts,tsx}",
      "!**/__tests__/**",
      "!**/coverage/**",
      "!**/node_modules/**",
      "!**/.expo/**",
      "!**/expo-env.d.ts"
    ]
  }
}

// jest.setup.ts
import "@testing-library/react-native";
 
// Reset module mocks between tests when you use jest.mock at file scope.
afterEach(() => {
  jest.clearAllMocks();
});

// tsconfig.json (excerpt - enables Jest globals in TypeScript)
{
  "compilerOptions": {
    "types": ["jest"]
  }
}

// src/components/greeting.tsx
import { StyleSheet, Text, View } from "react-native";
 
export function Greeting({ name }: { name: string }) {
  return (
    <View style={styles.container}>
      <Text accessibilityRole="header">Hello, {name}</Text>
    </View>
  );
}
 
const styles = StyleSheet.create({
  container: { padding: 16 },
});

// __tests__/greeting-test.tsx
import { render, screen } from "@testing-library/react-native";
import { Greeting } from "../src/components/greeting";
 
describe("<Greeting />", () => {
  test("renders the name", () => {
    render(<Greeting name="Alex" />);
    expect(screen.getByRole("header", { name: "Hello, Alex" })).toBeOnTheScreen();
  });
 
  test("matches snapshot for stable markup", () => {
    const { toJSON } = render(<Greeting name="Alex" />);
    expect(toJSON()).toMatchSnapshot();
  });
});

What this demonstrates:

• jest-expo preset - zero custom Babel config for standard Expo projects.
• transformIgnorePatterns - transpiles ESM packages Jest would otherwise skip.
• jest.setup.ts - imports RNTL once so Jest matchers (toBeOnTheScreen) are registered.
• *-test.tsx naming - recognized by jest-expo without extra testMatch config.
• Snapshot on a leaf component - not the whole app shell.

Deep Dive

How It Works

• jest-expo preset extends Jest with Expo-aware transforms, module name mappers, and built-in mocks for most expo-* and React Native internals.
• Test Renderer (via @testing-library/react-native) renders components to a JS tree - no native view hierarchy, no simulator.
• transformIgnorePatterns tells Jest which node_modules packages to run through Babel; without it, imports from react-native, expo-router, or navigation packages throw syntax errors.
• setupFilesAfterEnv runs after the test framework installs - ideal for global matchers, mock resets, and shared jest.mock setup.
• Fake timers in setup are optional; enable per-file when testing setTimeout, animations, or debounced search.

Jest Config at a Glance

Module Path Aliases

When tsconfig.json maps @/* to ./src/*, mirror it in Jest:

"jest": {
  "preset": "jest-expo",
  "moduleNameMapper": {
    "^@/(.*)$": "<rootDir>/src/$1"
  }
}

Snapshot Discipline

Expo's own docs recommend Maestro E2E over snapshot tests for full UI flows - snapshots complement, not replace, integration and E2E coverage.

TypeScript Notes

// jest.setup.ts - typed mock helpers for native modules
import "@testing-library/react-native";
 
type ExpoLocationMock = {
  requestForegroundPermissionsAsync: jest.Mock;
  getCurrentPositionAsync: jest.Mock;
};
 
export function getLocationMock(): ExpoLocationMock {
  return jest.requireMock("expo-location") as ExpoLocationMock;
}

• Add "jest" to compilerOptions.types so describe, it, and expect type-check.
• Install @types/jest via expo install to stay aligned with the SDK's Jest version.
• Prefer jest.MockedFunction<typeof fn> over any when typing mocked imports.

Gotchas

• Tests inside app/ with Expo Router - Every file under app/ must be a route or layout. Fix: Put tests in __tests__/ at the project root or colocate *.test.tsx next to src/components/.

• "Cannot use import statement outside a module" - A dependency ships ESM and Jest skips transpiling it. Fix: Add the package to transformIgnorePatterns (or use the full Expo-recommended regex above).

• Forgetting test-renderer - @testing-library/react-native depends on the standalone test-renderer package (not deprecated react-test-renderer). Fix: npx expo install test-renderer --dev.

• Matchers like toBeOnTheScreen not found - RNTL extends Jest only after you import from @testing-library/react-native. Fix: Add import "@testing-library/react-native" to jest.setup.ts.

• Snapshots that never fail - Giant snapshots of screens with timestamps, random IDs, or fetched data create noise. Fix: Snapshot presentational components with fixed props; test data-driven UI with queries and assertions.

• Running jest without jest-expo - Plain Jest does not mock expo-constants, expo-font, or native modules. Fix: Always set "preset": "jest-expo" in package.json or jest.config.js.

• Watch mode in CI - --watchAll hangs CI runners. Fix: Use "test:ci": "jest --ci --coverage=false" in pipelines and pre-merge checks.

Alternatives

FAQs

npx expo install jest-expo jest @types/jest @testing-library/react-native test-renderer --dev

"test:ci": "jest --ci --coverage=false --changedSince=origin/main"

jest.mock("expo-font", () => ({
  loadAsync: jest.fn(() => Promise.resolve()),
  isLoaded: jest.fn(() => true),
}));
 
jest.mock("expo-splash-screen", () => ({
  preventAutoHideAsync: jest.fn(() => Promise.resolve()),
  hideAsync: jest.fn(() => Promise.resolve()),
}));

Related

• Mobile Testing Basics - unit → component → integration → E2E pyramid
• React Native Testing Library - queries, async, and user-centric assertions
• Mocking Native Modules - manual mocks beyond jest-expo defaults
• Maestro E2E - YAML flows when Jest is not enough
• Container/Presenter on Mobile - presenters are ideal Jest + RNTL targets
• GitHub Actions Integration - wire test:ci into PR checks

Stack versions: This page was written for React 19.2.3, React Native 0.86.0, and Expo SDK 57 (expo ~57.0.4).