Deploying and running gtests on Fuchsia.

Fuchsia gtest binaries are deployed and executed via scripts that are automatically generated by the fuchsia_package_runner() GN target. The binaries can deploy to either emulators started by the runner script, an existing emulator instance, or a physical device. To build a gtest binary, check this documentation.

For the sake of this example, we will be using base_unittests as the package we wish to install and/or execute.

Hermetic emulation

The test script brings up an emulator, runs the tests on it, and shuts the emulator down when finished.

$ out/fuchsia/bin/run_base_unittests

The flag --custom-image can be used to specify the Fuchsia boot image used by the emulator. For instance, setting --custom-image=workstation.qemu-x64-release would run the test on a workstation image.

Run on an physical device

Note the -d flag, which is an alias for --device.

$ out/fuchsia/bin/run_base_unittests -d

Run on a device paved with Fuchsia built from source

Make sure that the CPU architecture of your Chromium output directory matches the architecture of the Fuchsia output directory (x64==x64, arm64==arm64, etc.).

$ out/fuchsia/bin/run_base_unittests -d
--fuchsia-out-dir=/path/to/fuchsia/outdir

If you are frequently deploying to Fuchsia built from source, you might want to add the following entry to your args.gn:

default_fuchsia_build_dir_for_installation = "/path/to/fuchsia/outdir"

With this flag in place, the --fuchsia-out-dir flag will automatically be used whenever you run_ or install_ Fuchsia packages, making your command lines much shorter:

$ out/fuchsia/bin/run_base_unittests -d

Install on a device running Fuchsia built from source

$ out/fuchsia/bin/install_base_unittests
--fuchsia-out-dir=/path/to/fuchsia/outdir

You will need to run the package manually on your device. In this case, run the following from your Fuchsia directory:

$ fx shell run fuchsia-pkg://fuchsia.com/base_unittests#meta/base_unittests.cmx

Run on a device the host is connected to remotely via ssh

Note the --ssh-config flag, which should point to the config file used to set up the connection between the host and the remote device.

$ out/fuchsia/bin/run_base_unittests -d
--host=localhost --ssh-config=/path/to/ssh/config

Troubleshooting a test

To troubleshoot a specific test, consider a combination of the following arguments to the test runner script:

  • --gtest_filter="[TestSuite.TestName]" to only run a specific test, or a comma-separated list to run a set of tests. Wildcards can also be used to run a set of tests or an entire test suite, e.g. --gtest_filter="[TestSuite.*]".
  • --test-launcher-jobs=1 to only have one batch of tests running at a time. This bypasses the test launcher buffering of test log output, making it possible to access the log output from successful test runs.
  • --single-process-tests to run all the tests in the same process. Unlike the above option, this will run the tests directly in the test launcher process, making it easier to attach a debugger.
  • "--logs-dir=[/path/to/log/directory]` to specify the directory to write logs to. By default, Chromium logs are written to the “system_log” file in that directory.
  • --gtest_repeat=[number] --gtest_break_on_failure to run a test or test suite a certain number of times until it fails. This is useful to investigate flaky tests.