how to run mobile tests in CI with emulators

TL;DR

Run emulators headless in CI with hardware acceleration, keep one emulator per job, and accept that mobile e2e is slower: split it from the fast suite.

Error

(Not an error; a setup guide. The challenge: emulators are heavy and slow in CI.)

Steps

1. Use a CI image with the Android SDK or Xcode preinstalled. Expected: no SDK downloads per run.
2. Create the emulator once: avdmanager create avd with an x86_64 image. Expected: a defined device.
3. Boot headless with -no-window -no-audio and wait for sys.boot_completed. Expected: deterministic boot.
4. Enable hardware acceleration (KVM on Linux runners). Expected: usable speed.
5. Run the mobile suite as its own job, possibly nightly. Expected: does not block every PR.

When to use

• Adding Appium/Detox/Espresso/XCUITest to CI.
• You need real-device-ish fidelity.

When not to use

• Unit tests (run on the JVM/Node directly).
• Every-PR gating (too slow; use nightly).

Tool compatibility

• Android emulator, iOS simulator; Appium, Detox, Espresso, XCUITest.

Variant phrasings

Android emulator in CI

The Android-specific setup.

iOS simulator GitHub Actions

The iOS-specific setup; macOS runners required.

Why it happens

Mobile tests need a device. Emulators provide it, but they are resource-hungry and slow to boot.

Edge cases

• macOS runners are required for iOS simulators and cost more.
• Emulator snapshots speed up boot dramatically; use them.
• Flakiness is higher on emulators; budget retries.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_TJohTtHmPSxuvz8Bg72TRg