The following dependencies should be installed in order to be able to run tests:
- OpenJDK
- Android NDK
- Android SDK
To manage the dependencies, you can install them via terminal or using Android Studio.
OpenJDK can be installed on Linux (Ubuntu) using apt-get
:
sudo apt-get install openjdk-8-jdk zip unzip
Android SDK and NDK can be automatically installed via the following script:
#!/usr/bin/env bash
set -e
NDK_VER=r27c
SDK_VER=9123335_latest
SDK_API_LEVEL=33
SDK_BUILD_TOOLS=33.0.1
if [[ "$OSTYPE" == "darwin"* ]]; then
HOST_OS=darwin
HOST_OS_SHORT=mac
BASHRC=~/.zprofile
else
HOST_OS=linux
HOST_OS_SHORT=linux
BASHRC=~/.bashrc
fi
# download Android NDK
export ANDROID_NDK_ROOT=~/android-ndk-${NDK_VER}
curl https://dl.google.com/android/repository/android-ndk-${NDK_VER}-${HOST_OS}.zip -L --output ~/andk.zip
unzip ~/andk.zip -d $(dirname ${ANDROID_NDK_ROOT}) && rm -rf ~/andk.zip
# download Android SDK, accept licenses and download additional packages such as
# platform-tools, platforms and build-tools
export ANDROID_SDK_ROOT=~/android-sdk
curl https://dl.google.com/android/repository/commandlinetools-${HOST_OS_SHORT}-${SDK_VER}.zip -L --output ~/asdk.zip
mkdir ${ANDROID_SDK_ROOT} && unzip ~/asdk.zip -d ${ANDROID_SDK_ROOT}/cmdline-tools && rm -rf ~/asdk.zip
yes | ${ANDROID_SDK_ROOT}/cmdline-tools/cmdline-tools/bin/sdkmanager --sdk_root=${ANDROID_SDK_ROOT} --licenses
${ANDROID_SDK_ROOT}/cmdline-tools/cmdline-tools/bin/sdkmanager --sdk_root=${ANDROID_SDK_ROOT} "platform-tools" "platforms;android-${SDK_API_LEVEL}" "build-tools;${SDK_BUILD_TOOLS}"
Android Studio offers a convenient UI:
- to install all the dependencies;
- to manage android virtual devices;
- to make easy use of adb logs.
Before running a build you might want to set the Android SDK and NDK environment variables:
export ANDROID_SDK_ROOT=<PATH-TO-ANDROID-SDK>
export ANDROID_NDK_ROOT=<PATH-TO-ANDROID-NDK>
Now we're ready to build everything for Android:
./build.sh mono+libs -os android -arch x64
and even run tests one by one for each library:
./build.sh libs.tests -os android -arch x64 -test
Make sure an emulator is booted (see AVD Manager
) or a device is plugged in and unlocked.
AVD Manager
tool recommends to install x86
images by default so if you follow that recommendation make sure -arch x86
was used for the build script.
The following shows how to run tests for a specific library
./dotnet.sh build /t:Test src/libraries/System.Numerics.Vectors/tests /p:TargetOS=android /p:TargetArchitecture=x64
There are functional tests which aim to test some specific features/configurations/modes on a target mobile platform.
A functional test can be run the same way as any library test suite, e.g.:
./dotnet.sh build /t:Test -c Release /p:TargetOS=android /p:TargetArchitecture=x64 src/tests/FunctionalTests/Android/Device_Emulator/PInvoke/Android.Device_Emulator.PInvoke.Test.csproj
Currently functional tests are expected to return 42
as a success code so please be careful when adding a new one.
It's possible to test various configurations by setting a combination of additional MSBuild properties such as RunAOTCompilation
,MonoForceInterpreter
, and some more.
- AOT
To build for AOT only mode, add /p:RunAOTCompilation=true /p:MonoForceInterpreter=false
to a build command.
- AOT-LLVM
To build for AOT-LLVM mode, add /p:RunAOTCompilation=true /p:MonoForceInterpreter=false /p:MonoEnableLLVM=true
to a build command.
- Interpreter
To build for Interpreter mode, add /p:RunAOTCompilation=false /p:MonoForceInterpreter=true
to a build command.
Android app is basically a Java Instrumentation and a simple Activity that inits the Mono Runtime via JNI. This Mono Runtime starts a simple xunit test
runner called XHarness.TestRunner (see https://github.com/dotnet/xharness) which runs tests for all *.Tests.dll
libs in the bundle. There is also XHarness.CLI tool with ADB embedded to deploy *.apk
to a target (device or emulator) and obtain logs once tests are completed.
XHarness for Android doesn't talk much and only saves test results to a file. However, you can also subscribe to live logs via the following command:
adb logcat -s "DOTNET"
Or simply open logcat
window in Android Studio or Visual Studio.
If Android Studio is installed, AVD Manager can be used from the IDE to create and start Android virtual devices. Otherwise, the Android SDK provides the avdmanager
command line tool.
Example of installing, creating, and launching emulators from the command line (where SDK_API_LEVEL
matches the installed Android SDK and EMULATOR_NAME_X86
/EMULATOR_NAME_X64
are names of your choice):
# Install x86 image
${ANDROID_SDK_ROOT}/cmdline-tools/tools/bin/sdkmanager "system-images;android-${SDK_API_LEVEL};default;x86"
# Create x86 image
${ANDROID_SDK_ROOT}/cmdline-tools/tools/bin/avdmanager create avd --name ${EMULATOR_NAME_X86} --package "system-images;android-${SDK_API_LEVEL};default;x86"
# Launch emulator with x86 image
${ANDROID_SDK_ROOT}/emulator/emulator -avd ${EMULATOR_NAME_X86} &
# Install x64 image
${ANDROID_SDK_ROOT}/cmdline-tools/tools/bin/sdkmanager "system-images;android-${SDK_API_LEVEL};default;x86_64"
# Create x64 image
${ANDROID_SDK_ROOT}/cmdline-tools/tools/bin/avdmanager create avd --name ${EMULATOR_NAME_X64} --package "system-images;android-${SDK_API_LEVEL};default;x86_64"
# Launch emulator with x64 image
${ANDROID_SDK_ROOT}/emulator/emulator -avd ${EMULATOR_NAME_X64} &
The emulator can be launched with a variety of options. Run emulator -help
to see the full list.
-os android
is not supported for Windows yet (WSL
can be used instead)- XHarness.CLI is not able to boot emulators yet (so you need to boot via
AVD Manager
or IDE) - AOT and Interpreter modes are not supported yet
The Android NDK has two release channels: a rolling release, which occurs approximately every quarter, and a Long Term Support (LTS) release, which happens once a year (typically in Q3). While release dates are not guaranteed, LTS versions receive support for at least one year or until the next LTS reaches the release candidate stage. After that, the NDK version stops receiving bug fixes and security updates.
The LTS NDK release schedule roughly aligns with the .NET Release Candidate (RC) timeline. Given this, we should plan to upgrade the NDK version used in main
around that time. If we successfully upgrade before .NET release, we can ensure that our CI builds and tests run against a supported NDK version for approximately 9 months after the release.
.NET MAUI is supported for 18 months after each .NET release. This means the NDK version used in CI will be supported for about half the lifecycle of a given .NET MAUI release. If we want to ensure that the NDK version used in CI is supported for the entire lifecycle of a given .NET MAUI release, we should consider upgrading the NDK version in the release
branches.
CI pipelines retrieve the NDK version from Docker images hosted in the dotnet-buildtools-prereqs-docker repository.
For reference, see an example Dockerfile NDK definition: Azure Linux 3.0 .NET 10.0 Android Dockerfile.
Bumping version of the NDK in the prereqs repo will automatically propagate it to all CI runs Thus, bumping the NDK requires a three step process in order to ensure that CI continues to operate correctly. To upgrade the NDK version used in CI for building and testing Android, follow these steps:
- Download the new NDK version.
- Test the local build using the new NDK by building a sample Android app.
- Ensure AOT and AOT_WITH_LIBRARY_FILES are enabled in the build.
- Create a new Docker image containing the updated NDK version (based on the original docker image from the dotnet-buildtools-prereqs-docker repository).
- Open a draft PR in the runtime repository that updates the Dockerfile reference to use the new image.
- Monitor CI results and fix any failures.
- Once CI is green, commit only the necessary changes (e.g., fixes, build adjustments) to the respective branch.
- Do not change the Docker image reference in the final commit.
- Update the NDK version in the dotnet-buildtools-prereqs-docker repository by modifying the Dockerfile.
- The updated NDK will automatically flow to all builds of a given branch once merged.
By following these steps, you ensure a smooth upgrade of the Android NDK in CI while maintaining stability and compatibility.