Running tests

The testing strategy for Perfetto is rather complex due to the wide variety of build configurations and embedding targets.

Common test targets (all platforms / checkouts):

Platform-agnostic unit-tests.

End-to-end tests, involving the protobuf-based IPC transport and ftrace integration (Linux/Android only).

Benchmarks tracking the performance of: (i) trace writing, (ii) trace readback and (iii) ftrace raw pipe -> protobuf translation.

Running tests on Linux / MacOS

tools/ninja -C out/default perfetto_{unittests,integrationtests,benchmarks} out/default/perfetto_unittests --gtest_help

perfetto_integrationtests requires that the ftrace debugfs directory is is readable/writable by the current user on Linux:

sudo chown -R $USER /sys/kernel/debug/tracing

Running tests on Android

1A) Connect a device through adb
1B) Start the build-in emulator (supported on Linux and MacOS):

tools/install-build-deps --android tools/run_android_emulator &
  1. Run the tests (either on the emulator or physical device):
tools/run_android_test out/default perfetto_unittests

Continuous testing

Perfetto is tested in a variety of locations:

Perfetto CI:
Builds and runs perfetto_{unittests,integrationtests,benchmarks} from the standalone checkout. Benchmarks are ran in a reduced form for smoke testing. See this doc for more details.

Android CI (see go/apct and go/apct-guide):
runs only perfetto_integrationtests

Android presubmits (TreeHugger):
Runs before submission of every AOSP CL of external/perfetto.

Android CTS (Android test suite used run to ensure API compatibility):
Rolling runs internally.

Note that Perfetto CI uses the standalone build system and the others build as part of the Android tree.

Unit tests

Unit tests exist for most of the code in Perfetto on the class level. They ensure that each class broadly works as expected.

Unit tests are currently ran on and Running unit tests on APCT and Treehugger is WIP.

Integration tests

Integration tests ensure that subsystems (importantly ftrace and the IPC layer) and Perfetto as a whole is working correctly end-to-end.

There are two configurations in which integration tests can be run:

1. Production mode (Android-only)
This mode assumes that both the tracing service (traced) and the OS probes service (traced_probes) are already running. In this mode the test enables only the consumer endpoint and tests the interaction with the production services. This is the way our Android CTS and APCT tests work.

2. Standalone mode:
Starting up the daemons in the test itself and then testing against them. This is how standalone builds are tested. This is the only supported way to run integration tests on Linux and MacOS.

Trace Processor diff tests

Trace processor is mainly tested using so called "diff tests".

For these tests, trace processor parses a known trace and executes a query file. The output of these queries is then compared (i.e. "diff"ed) against an expected output file and discrepencies are highlighted.

Similar diff tests are also available when writing metrics - instead of a query file, the metric name is used and the expected output file contains the expected result of computing the metric.

These tests (for both queries and metrics) can be run as follows:

tools/ninja -C <out directory> tools/ <out directory>/trace_processor_shell

To add a new diff test (for query tests only), the tools/ script is useful. It will automatically create the query and expected output files and adds them both to the index. For metrics, this has to be done manually for now.

TIP: Query diff tests are expected to only have a single query which produces output in the whole file (usually at the end). Calling SELECT RUN_METRIC('metric file') can trip up this check as this query generates some hidden output. To address this issue, if a query only has column is named suppress_query_output, even if it has output, this will be ignored (for example, SELECT RUN_METRIC('metric file') as suppress_query_output)

UI pixel diff tests

The pixel tests are used to ensure core user journeys work by verifying they are the same pixel to pixel against a golden screenshot. They use a headless chrome to load the webpage and take a screenshot and compare pixel by pixel a golden screenshot. You can run these tests by using ui/run-integrationtests.

These test fail when a certain number of pixels are different. If these tests fail, you'll need to investigate the diff and determine if its intentional. If its a desired change you will need to update the screenshots on a linux machine to get the CI to pass. You can update them by generating and uploading a new baseline (this requires access to a google bucket through gcloud which only googlers have access to, googlers can install gcloud here).

ui/run-integrationtests --rebaseline tools/test_data upload

Once finished you can commit and upload as part of your CL to cause the CI to use your new screenshots.

NOTE: If you see a failing diff test you can see the pixel differences on the CI by using a link ending with ui-test-artifacts/index.html. Report located on that page contains changed screenshots as well as a command to accept the changes if these are desirable.

Android CTS tests

CTS tests ensure that any vendors who modify Android remain compliant with the platform API.

These tests include a subset of the integration tests above as well as adding more complex tests which ensure interaction between platform (e.g. Android apps etc.) and Perfetto is not broken.

The relevant targets are CtsPerfettoProducerApp and CtsPerfettoTestCases. Once these are built, the following commands should be run:

adb push $ANDROID_HOST_OUT/cts/android-cts/testcases/CtsPerfettoTestCases64 /data/local/tmp/ adb install -r $ANDROID_HOST_OUT/cts/android-cts/testcases/CtsPerfettoProducerApp.apk

Next, the app named android.perfetto.producer should be run on the device.

Finally, the following command should be run:

adb shell /data/local/tmp/CtsPerfettoTestCases64

Chromium waterfall

Perfetto is constantly rolled into chromium's //third_party/perfetto via this autoroller.

The Chromium CI runs the perfetto_unittests target, as defined in the buildbot config.