Audio driver tests

The audio driver test suites validate implementations of the interfaces fuchsia.hardware.audio.Codec, fuchsia.hardware.audio.Composite, fuchsia.hardware.audio.Dai, fuchsia.hardware.audio.Health, fuchsia.hardware.audio.RingBuffer, fuchsia.hardware.audio.StreamConfig and fuchsia.hardware.audio.signalprocessing.

Test targets

These suites detect, initialize and test all audio device drivers registered with devfs under /dev/class/audio-composite /dev/class/audio-input, /dev/class/audio-output, /dev/class/codec and /dev/class/dai. Drivers are tested non-hermetically, validating them when running on the hardware for which they were written.

The suites also create and test a number of virtual_audio driver instances, using default settings. These tests can be disabled with the --no-virtual flag.

The suites also create and test a private instance of the Bluetooth audio library (see //src/connectivity/bluetooth/tests/audio-device-output-harness). These tests can be disabled by specifying --no-bluetooth.

Test case groups

With the exception of a few fuchsia.hardware.audio.StreamConfig methods, audio drivers are intended to have only a single connected client at any time. Some products (those with ‘user’ and ‘userdebug’ build flavors, although this applies to their ‘eng’ variants as well) demand-start either audio_core or audio_device_registry early in the boot-up process, triggering audio device initialization and configuration. This means that on these products, audio_core or audio_device_registry will connect to the RingBuffers of detected audio devices before these tests can run, thus blocking the majority of test cases from working as expected.

audio_driver_tests uses generous timeout durations, enabling these tests to function correctly even in heavily loaded test execution environments such as a device emulator instance on a multi-tenant CQ server, or a build compiled with significant instrumentation (ASAN) or without standard optimizations (debug). However, audio drivers are part of the real-time data path, and certain test cases (see position_test.cc) should only be executed in an environment capable of real-time response.

For these reasons, there are distinct test suites that each execute a subset of the audio driver test cases suggested above.

Test suites

audio_driver_basic_tests assumes that an audio service is present and running; it runs only “basic” StreamConfig-related tests (see basic_test.cc) that can execute even when audio_core is already connected to a StreamConfig driver.

audio_driver_admin_tests runs “privileged” test cases that (1) reconfigure devices without restoring the previous state, or (2) use interfaces such as RingBuffer that can only be allocated to one client at a time (and thus cannot be validated by “basic” tests that assume audio_core/audio_device_registry is already present and running). Note: audio services can be manually demand- started on core, minimal or other builds that include but do not auto-start them; if for any reason audio_core or audio_device_registry is running, the “admin” tests will fail (first with error code ZX_ERR_PEER_CLOSED, followed by error code ZX_ERR_INVALID_ARGS).

audio_driver_realtime_tests runs the small subset of test cases that require real-time response (e.g. ring-buffer position tests). These tests require the same type of exclusive access needed by “admin” tests.

Command-line configuration

Each test suite automatically executes one subset of tests, but can enable the others by specifying cmdline flags when fx test is invoked. These flags are --basic, --admin and --position. The --all flag enables all three.

In addition to these flags, there are the --no-virtual and no-bluetooth flags mentioned above, as well as --help and --? which explain all this.

Note: all flags mentioned here are suite-specific. Any fx test command that includes them must include an extra -- before these flags.

Thus, to fully validate a devfs-based audio driver, execute any of the following in a release build running on a non-emulated system:

 fx test audio_driver_basic_tests -- --all
 fx test audio_driver_admin_tests -- --all
 fx test audio_driver_realtime_tests -- --all

To further avoid re-testing virtual_audio instances or the Bluetooth audio library, add the two related flags, such as:

 fx test audio_driver_realtime_tests -- --basic --admin --no-virtual --no-bluetooth