ART Chroot-Based On-Device Testing

This file documents the use of a chroot environment in on-device testing of the Android Runtime (ART). Using a chroot allows tests to run a standalone ART from a locally built source tree on a device running (almost any) system image and does not interfere with the Runtime installed in the device's system partition.

Introduction

The Android Runtime (ART) supports testing in a chroot-based environment, by setting up a chroot directory in a ART_TEST_CHROOT directory located under /data/local (e.g. ART_TEST_CHROOT=/data/local/art-test-chroot) on a device, installing ART and all other required artifacts there, and having tests use adb shell chroot $ART_TEST_CHROOT <command> to execute commands on the device within this environment.

This way to run tests using a "standalone ART" ("guest system") only affects files in the data partition (the system partition and other partitions are left untouched) and is as independent as possible from the Android system ("host system") running on the device. This has some benefits:

no need to build and flash a whole device to do ART testing (or "overwriting" an existing ART by syncing the system partition);
the possibility to use a smaller AOSP Android manifest (master-art) to build ART and the required dependencies for testing;
no instability due to updating/replacing ART on the system partition (a functional Android Runtime is necessary to properly boot a device);
the possibility to have several standalone ART instances (one per directory, e.g. /data/local/art-test-chroot1, /data/local/art-test-chroot2, etc.).

Note that using this chroot-based approach requires root access to the device (i.e. be able to run adb root successfully).

Quick User Guide

Unset variables which are not used with the chroot-based approach (if they were set previously):

unset ART_TEST_ANDROID_ROOT
unset CUSTOM_TARGET_LINKER
unset ART_TEST_ANDROID_ART_ROOT
unset ART_TEST_ANDROID_RUNTIME_ROOT
unset ART_TEST_ANDROID_I18N_ROOT
unset ART_TEST_ANDROID_TZDATA_ROOT

Set the chroot directory in ART_TEST_CHROOT:

export ART_TEST_CHROOT=/data/local/art-test-chroot

Set lunch target and ADB:

With a minimal aosp/master-art tree:

export SOONG_ALLOW_MISSING_DEPENDENCIES=true
. ./build/envsetup.sh
lunch armv8-eng  # or arm_krait-eng for 32-bit ARM
export PATH="$(pwd)/prebuilts/runtime:$PATH"
export ADB="$ANDROID_BUILD_TOP/prebuilts/runtime/adb"

With a full Android (AOSP) aosp/master tree:

export OVERRIDE_TARGET_FLATTEN_APEX=true
. ./build/envsetup.sh
lunch aosp_arm64-eng  # or aosp_arm-eng for 32-bit ARM
m adb

Build ART and required dependencies:
```
art/tools/buildbot-build.sh --target
```
Clean up the device:
```
art/tools/cleanup-buildbot-device.sh
```
Setup the device (including setting up mount points and files in the chroot directory):
```
art/tools/setup-buildbot-device.sh
```
Populate the chroot tree on the device (including "activating" APEX packages in the chroot environment):
```
art/tools/buildbot-sync.sh
```
Run ART gtests:
```
art/tools/run-gtests.sh -j4
```
- Note: This currently fails on test test-art-target-gtest-image_space_test{32,64} when using the full AOSP tree (b/119815008).
  - Workaround: Run m clean-oat-host before the build step (art/tools/buildbot-build.sh --target) above.
- Note: The -j option is not honored yet (b/129930445).
- Specific tests to run can be passed on the command line, specified by their absolute paths beginning with /apex/.

Run ART run-tests:

On a 64-bit target:

art/test/testrunner/testrunner.py --target --64

On a 32-bit target:

art/test/testrunner/testrunner.py --target --32

Run Libcore tests:

On a 64-bit target:

art/tools/run-libcore-tests.sh --mode=device --variant=X64

On a 32-bit target:

art/tools/run-libcore-tests.sh --mode=device --variant=X32

Run JDWP tests:

On a 64-bit target:

art/tools/run-jdwp-tests.sh --mode=device --variant=X64

On a 32-bit target:

art/tools/run-jdwp-tests.sh --mode=device --variant=X32

Tear down device setup:
```
art/tools/teardown-buildbot-device.sh
```
Clean up the device:
```
art/tools/cleanup-buildbot-device.sh
```