This repository documents how to set-up an Android Studio project with .gradle with:

• A shared library module (with unit tests)
• An Android app target (with unit and instrumentation tests)
• A cross-platform CLI .jar target
• A GitHub actions configurations

I found this kind of configuration helpful when iterating on algorithms in libraries. With the CLI .jar target I am able to run them locally on my machine (and beefy servers) against larger inputs. It also allows to create a local UI application for QA.

Project layout

The project consists of three modules:

:lib contains the shared library code and should only rely on pure Java/Kotlin dependencies. It comes with unit tests.

:app contains a sample Android application with a minimal UI. It comes with both unit tests and instrumented UI tests (using espresso).

:cli contains a sample CLI application that can run on "normal" computers from the command line. It is configured to build a "fat jar" which bundles all dependencies similar to how one is used to from .apk files.

Running

The following commands run through the important bits of this project:

# Clean everything (often a good idea)
./gradlew clean

# Build and unit test library
./gradlew :lib:test

# Build CLI .jar and run it
./gradlew :cli:jar
java -jar ./cli/build/libs/cli.jar "Hello"

# Unit test app
./gradlew :app:test

# Instrumented test of the app (using Espresso)
./gradlew :app:connectedAndroidTest

# Run app
./gradlew :app:installDebug
adb shell am start -n org.example.droidjar.app/.MainActivity