Testing the NDK

The latest version of this document is available at https://android.googlesource.com/platform/ndk/+/master/docs/Testing.md.

The NDK tests are built as part of a normal build (with checkbuild.py) and run with run_tests.py. See Building.md for more instructions on building the NDK.

From the NDK source directory (./ndk within the directory you ran repo init in, or the root of the cloned directory if you cloned only the NDK project).

$ ./checkbuild.py  # Build the NDK and tests.
$ ./run_tests.py

Running the tests requires adb in your path and compatible devices attached. If you're having trouble with the version from the SDK manager, try a version built fresh from AOSP.

The test runner will look for any attached devices that match the requirements listed in the devices section of the test configuration file (see qa_config.json for the defaults, or use --config to choose your own). Each test will be run on all devices compatible with that test.

The full QA configuration takes roughly 10 minutes to run (P920 Linux host, 4 Galaxy Nexūs for Jelly Bean, 2 Pixels for Pie, 1 emulator for x86-64 Pie). Attaching multiple devices will allow the test runner to shard tests among those devices. Pushing tests can take up a large portion of the test time (3 of the 10 minutes quoted above), but adb push --sync is used to prevent unnecessary pushes on reruns or when only a subset of tests are rebuilt.

The tests can be rebuilt without running checkbuild.py (which is necessary in the case of not having a full NDK checkout, as you might when running the Windows tests on a release from the build server) with run_tests.py --rebuild.

Restricting Test Configurations

By default, all of the configurations we test are built from both checkbuild.py and run_tests.py --rebuild. This runs tens of thousands of test executables. Each test is built in 4 different configurations (once for each ABI) at time of writing. The set of configurations built can be restricted in two ways.

First, run_tests.py --config myconfig.json will use an alternate test configuration file (the default is qa_config.json).

Second, and simpler for a development workflow, the following flag can be used to restrict the configurations (the presence of any of this flag will override the matching entry in the config file, but otherwise the config file is obeyed):

$ ./run_tests.py --rebuild --abi armeabi-v7a

Configuration filtering flags are repeatable. For example, --abi armeabi-v7a --abi x86 will build both armeabi-v7a and x86 tests.

Beyond restricting test configurations, the tests themselves can be filtered with the --filter flag:

$ ./run_tests.py --filter test-googletest-full

Test filters support wildcards (as implemented by Python's fnmatch.fnmatch). The filter flag may be combined with the build configuration flags.

Putting this all together, a single test can be rebuilt and run for just armeabi-v7a, with the following command:

$ ./run_tests.py --rebuild \
    --abi armeabi-v7a \
    --filter test-googletest-full

Testing Releases

When testing a release candidate, your first choice should be to run the test artifacts built on the build server for the given build. This is the ndk-tests.tar.bz2 artifact in the same directory as the NDK zip. Extract the tests somewhere, and then run:

$ ./run_tests.py path/to/extracted/tests

For Windows, test artifacts are not available since we cross compile the NDK from Linux rather than building on Windows. We want to make sure the Windows binaries we build work on Windows (using wine would only tell us that they work on wine, which may not be bug compatible with Windows), so those must be built on the test machine before they can be run. To use the fetched NDK to build the tests, run:

$ ./run_tests.py --rebuild --ndk path/to/extracted/ndk out

Broken and Unsupported Tests

To mark tests as currently broken or as unsupported for a given configuration, add a test_config.py to the test's root directory (in the same directory as jni/).

Unsupported tests will not be built or run.

Broken tests will be built and run, and the result of the test will be inverted. A test that fails will become an “EXPECTED FAILURE” and not be counted as a failure, whereas a passing test will become an “UNEXPECTED SUCCESS” and count as a failure.

By default, run_tests.py will hide expected failures from the output since the caller is most likely only interested in seeing what effect their change had. To see the list of expected failures, pass --show-all.

Here's an example test_config.py that marks this test as broken when building for arm64 and unsupported when running on a pre-Lollipop device:

from typing import Optional

from ndk.test.devices import Device
from ndk.test.types import Test

def build_broken(test: Test) -> tuple[Optional[str], Optional[str]]:
    if test.abi == 'arm64-v8a':
        return test.abi, 'https://github.com/android-ndk/ndk/issues/foo'
    return None, None

def run_unsupported(test: Test, device: Device) -> Optional[str]:
    if device.version < 21:
        return f'{device.version}'
    return None

The *_broken checks return a tuple of (broken_configuration, bug_url) if the given configuration is known to be broken, else (None, None).

The *_unsupported checks return broken_configuration if the given configuration is unsupported, else None.

The configuration is specified by the following arguments:

  • abi: The ABI being built for.
  • platform: The platform version being built for. Not necessarily the platform version that the test will be run on.
  • device_api: The API level of the device the test will be run on.
  • name: This is the name of the test executable being run. For libc++ tests built by LIT, the executable will be foo.pass.cpp.exe, but name will be foo.pass.

Devices and Emulators

For testing a release, make sure you're testing against the released user builds of Android.

For Nexus/Pixel devices, factory images are available here: https://developers.google.com/android/nexus/images.

For emulators, use emulator images from the SDK rather than from a platform build, as these are what our users will be using. Note that some NDK tests (namely test-googletest-full and asan-smoke) are known to break between emulator updates. It is not known whether these are NDK bugs, emulator bugs, or x86_64 system image bugs.

After installing the emulator images from the SDK manager, they can be configured and launched for testing with (assuming the SDK tools directory is in your path):

$ android create avd --name $NAME --target android-$LEVEL --abi $ABI
$ emulator -avd $NAME

This will create and launch a new virtual device.

ARM64 emulators are available in the SDK manager but emulated testing (as compared to virtualized testing on x86_64) is very slow. Physical devices are recommended for testing ARM64.

Windows VMs

Warning: the process below hasn't been tested in a very long time. Googlers should refer to http://go/ndk-windows-vm for slightly more up-to-date Google- specific setup instructions, but http://go/windows-cloudtop may be easier.

Windows testing can be done on Windows VMs in Google Compute Engine. To create one:

  • Install the Google Cloud SDK.
  • Run scripts/create_windows_instance.py $PROJECT_NAME $INSTANCE_NAME
    • The project name is the name of the project you configured for the VMs.
    • The instance name is whatever name you want to use for the VM.

This process will create a secrets.py file in the NDK project directory that contains the connection information.

The VM will have Chrome and Git installed and WinRM will be configured for remote command line access.

TODO: Implement run_tests.py --remote-build.