Example Android project with repeatable tests running inside an emulator

I’ve spent the last couple of days fighting the Android command line to set up a simple project that can run automated tests inside an emulator reliably and repeatably.

To make the tests reliable and independent from anything else on my machine, I wanted to store the Android SDK and AVD files in a local directory.

To do this I had to define a lot of inter-related environment variables, and wrap the tools in scripts that ensure they run with the right flags and settings.

The end result of this work is here: gitlab.com/andybalaam/android-skeleton

You need all the utility scripts included in that repo for it to work, but some highlights include:

The environment variables that I source in every script, scripts/paths:

PROJECT_ROOT=$(dirname $(dirname $(realpath ${BASH_SOURCE[${#BASH_SOURCE[@]} - 1]})))
export ANDROID_SDK_ROOT="${PROJECT_ROOT}/android_sdk"
export ANDROID_SDK_HOME="${ANDROID_SDK_ROOT}"
export ANDROID_EMULATOR_HOME="${ANDROID_SDK_ROOT}/emulator-home"
export ANDROID_AVD_HOME="${ANDROID_EMULATOR_HOME}/avd"

Creation of a local.properties file that tells Gradle and Android Studio where the SDK is, by running something like this:

echo "# File created automatically - changes will be overwritten!" > local.properties
echo "sdk.dir=${ANDROID_SDK_ROOT}" >> local.properties

The wrapper scripts for Android tools e.g. scripts/sdkmanager:

#!/bin/bash

set -e
set -u

source scripts/paths

"${ANDROID_SDK_ROOT}/tools/bin/sdkmanager" \
    "--sdk_root=${ANDROID_SDK_ROOT}" \
    "$@"

The wrapper for avdmanager is particularly interesting since it seems we need to override where it thinks the tools directory is for it to work properly – scripts/avdmanager:

#!/bin/bash

set -e
set -u

source scripts/paths

# Set toolsdir to include "bin/" since avdmanager seems to go 2 dirs up
# from that to find the SDK root?
AVDMANAGER_OPTS="-Dcom.android.sdkmanager.toolsdir=${ANDROID_SDK_ROOT}/tools/bin/" \
    "${ANDROID_SDK_ROOT}/tools/bin/avdmanager" "$@"

An installation script that must be run once before using the project scripts/install-android-tools:

#!/bin/bash

set -e
set -u
set -x

source scripts/paths

mkdir -p "${ANDROID_SDK_ROOT}"
mkdir -p "${ANDROID_AVD_HOME}"
mkdir -p "${ANDROID_EMULATOR_HOME}"

# Download sdkmanager, avdmanager etc.
cd "${ANDROID_SDK_ROOT}"
test -f commandlinetools-*.zip || \
    wget -q 'https://dl.google.com/android/repository/commandlinetools-linux-6200805_latest.zip'
unzip -q -u commandlinetools-*.zip
cd ..

# Ask sdkmanager to update itself
./scripts/sdkmanager --update

# Install the emulator and tools
yes | ./scripts/sdkmanager --install 'emulator' 'platform-tools'

# Platforms
./scripts/sdkmanager --install 'platforms;android-21'
./scripts/sdkmanager --install 'platforms;android-29'

# Install system images for our oldest and newest supported API versions
yes | ./scripts/sdkmanager --install 'system-images;android-21;default;x86_64'
yes | ./scripts/sdkmanager --install 'system-images;android-29;default;x86_64'

# Create AVDs to run the system images
echo no | ./scripts/avdmanager -v \
    create avd \
    -f \
    -n "avd-21" \
    -k "system-images;android-21;default;x86_64" \
    -p ${ANDROID_SDK_ROOT}/avds/avd-21
echo no | ./scripts/avdmanager -v \
    create avd \
    -f \
    -n "avd-29" \
    -k "system-images;android-29;default;x86_64" \
    -p ${ANDROID_SDK_ROOT}/avds/avd-29

Please do contribute to the project if you know easier ways to do this stuff.