emulator.wtf

emulator.wtf runs Android instrumentation tests on hosted emulators. Patrol tests need no special support there: build the APKs with patrol build android and hand them to ew-cli.

Before you proceed, make sure that you've completed the native setup guide.

Running tests

patrol build android

ew-cli \
  --app build/app/outputs/apk/debug/app-debug.apk \
  --test build/app/outputs/apk/androidTest/debug/app-debug-androidTest.apk \
  --device model=Pixel7,version=34 \
  --use-orchestrator

Credentials come from --token or the EW_API_TOKEN env var. See the ew-cli docs for devices, sharding and outputs.

Patrol can collect Dart line coverage on emulator.wtf the same way it does on BrowserStack: the app embeds it into the JaCoCo .ec files emulator.wtf already collects, and patrol coverage pull turns them into a patrol_lcov.info.

Instrument the app under test. In android/app/build.gradle.kts set enableAndroidTestCoverage = true (AGP 8+; testCoverageEnabled = true on AGP 7) on the debug build type.

Declare the storage permission in a debug-only manifest, android/app/src/debug/AndroidManifest.xml. ew-cli refuses to start a coverage run without it:

<manifest xmlns:android="http://schemas.android.com/apk/res/android">
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
</manifest>

On API levels below 29 the permission must also be granted at runtime; see emulator.wtf's coverage docs.

Build with the coverage dart-defines:

patrol build android --dart-define=PATROL_BS_COVERAGE=true --dart-define='PATROL_BS_COVERAGE_PACKAGES=^package:my_app/'

PATROL_BS_COVERAGE_PACKAGES and PATROL_BS_COVERAGE_FORCE_COMPILE work as described in the BrowserStack guide.

Run with coverage and keep package data between tests. Clearing it is incompatible with coverage, as on BrowserStack:

ew-cli \
  --app build/app/outputs/apk/debug/app-debug.apk \
  --test build/app/outputs/apk/androidTest/debug/app-debug-androidTest.apk \
  --device model=Pixel7,version=34 \
  --use-orchestrator --no-clear-package-data \
  --with-coverage \
  --outputs coverage \
  --outputs-dir ew-out

With the orchestrator, emulator.wtf downloads one .ec file per test into ew-out; without it, one per shard.

Split and merge the downloaded files:

patrol coverage pull --input ew-out --output coverage

This reads every .ec file under ew-out and writes coverage/jacoco.exec (Java/Kotlin) and coverage/patrol_lcov.info (Dart, merged across all tests and shards).

Running tests

Dart code coverage

On this page