DeviceLab is a physical lab that tests Flutter on real devices.
This package contains the code for the test framework and tests. More generally the tests are referred to as “tasks” in the API, but since we primarily use it for testing, this document refers to them as “tests”.
Current statuses for the devicelab are available at https://flutter-dashboard.appspot.com. See dashboard user guide for information on using the dashboards.
The DeviceLab devices continuously ask Flutter's continuous integration system Cocoon for tasks to run. When Cocoon has a task that is suitable for the device (e.g. Android test), it reserves that task for the device. See manifest.yaml for more information on the information used for scheduling tasks.
Do make sure your tests pass locally before deploying to the CI environment. Below is a handful of commands that run tests in a similar way to how the CI environment runs them. These commands are also useful when you need to reproduce a CI test failure locally.
You must set the ANDROID_SDK_ROOT environment variable to run tests on Android. If you have a local build of the Flutter engine, then you have a copy of the Android SDK at .../engine/src/third_party/android_tools/sdk.
You can find where your Android SDK is using flutter doctor.
Running the devicelab will do things to your environment.
Notably, it will start and stop Gradle, for instance.
To run all tests defined in manifest.yaml, use option -a (--all):
../../bin/cache/dart-sdk/bin/dart bin/run.dart -a
This defaults to only running tests supported by your host device's platform (--match-host-platform) and exiting after the first failure (--exit).
To run a test, use option -t (--task):
# from the .../flutter/dev/devicelab directory ../../bin/cache/dart-sdk/bin/dart bin/run.dart -t {NAME_OR_PATH_OF_TEST}
Where NAME_OR_PATH_OF_TEST can be either of:
manifest.yaml file in this directory. Example: complex_layout__start_up.bin/tasks. Tip: most shells support path auto-completion using the Tab key. Example: bin/tasks/complex_layout__start_up.dart.To run multiple tests, repeat option -t (--task) multiple times:
../../bin/cache/dart-sdk/bin/dart bin/run.dart -t test1 -t test2 -t test3
To run tests from a specific stage, use option -s (--stage). Currently, there are only three stages defined, devicelab, devicelab_ios and devicelab_win.
../../bin/cache/dart-sdk/bin/dart bin/run.dart -s {NAME_OF_STAGE}
To run device lab tests against a local engine build, pass the appropriate flags to bin/run.dart:
../../bin/cache/dart-sdk/bin/dart bin/run.dart --task=[some_task] \ --local-engine-src-path=[path_to_local]/engine/src \ --local-engine=[local_engine_architecture]
An example of a local engine architecture is android_debug_unopt_x86.
You can run an A/B test that compares the performance of the default engine against a local engine build. The test runs the same benchmark a specified number of times against both engines, then outputs a tab-separated spreadsheet with the results and stores them in a JSON file for future reference. The results can be copied to a Google Spreadsheet for further inspection and the JSON file can be reprocessed with the summarize.dart command for more detailed output.
Example:
../../bin/cache/dart-sdk/bin/dart bin/run.dart --ab=10 \ --local-engine=host_debug_unopt \ -t bin/tasks/web_benchmarks_canvaskit.dart
The --ab=10 tells the runner to run an A/B test 10 times.
--local-engine=host_debug_unopt tells the A/B test to use the host_debug_unopt engine build. --local-engine is required for A/B test.
--ab-result-file=filename can be used to provide an alternate location to output the JSON results file (defaults to ABresults#.json). A single # character can be used to indicate where to insert a serial number if a file with that name already exists, otherwise, the file will be overwritten.
A/B can run exactly one task. Multiple tasks are not supported.
Example output:
Score Average A (noise) Average B (noise) Speed-up bench_card_infinite_scroll.canvaskit.drawFrameDuration.average 2900.20 (8.44%) 2426.70 (8.94%) 1.20x bench_card_infinite_scroll.canvaskit.totalUiFrame.average 4964.00 (6.29%) 4098.00 (8.03%) 1.21x draw_rect.canvaskit.windowRenderDuration.average 1959.45 (16.56%) 2286.65 (0.61%) 0.86x draw_rect.canvaskit.sceneBuildDuration.average 1969.45 (16.37%) 2294.90 (0.58%) 0.86x draw_rect.canvaskit.drawFrameDuration.average 5335.20 (17.59%) 6437.60 (0.59%) 0.83x draw_rect.canvaskit.totalUiFrame.average 6832.00 (13.16%) 7932.00 (0.34%) 0.86x
The output contains averages and noises for each score. More importantly, it contains the speed-up value, i.e. how much faster is the local engine than the default engine. Values less than 1.0 indicate a slow-down. For example, 0.5x means the local engine is twice as slow as the default engine, and 2.0x means it's twice as fast. Higher is better.
Summarize tool example:
../../bin/cache/dart-sdk/bin/dart bin/summarize.dart --[no-]tsv-table --[no-]raw-summary \ ABresults.json ABresults1.json ABresults2.json ...
--[no-]tsv-table tells the tool to print the summary in a table with tabs for easy spreadsheet entry. (defaults to on)
--[no-]raw-summary tells the tool to print all per-run data collected by the A/B test formatted with tabs for easy spreadsheet entry. (defaults to on)
Multiple trailing filenames can be specified and each such results file will be processed in turn.
To reproduce the breakage locally git checkout the corresponding Flutter revision. Note the name of the test that failed. In the example above the failing test is flutter_gallery__transition_perf. This name can be passed to the run.dart command. For example:
../../bin/cache/dart-sdk/bin/dart bin/run.dart -t flutter_gallery__transition_perf
A test is a simple Dart program that lives under bin/tasks and uses package:flutter_devicelab/framework/framework.dart to define and run a task.
Example:
import 'dart:async'; import 'package:flutter_devicelab/framework/framework.dart'; Future<void> main() async { await task(() async { ... do something interesting ... // Aggregate results into a JSONable Map structure. Map<String, dynamic> testResults = ...; // Report success. return new TaskResult.success(testResults); // Or you can also report a failure. return new TaskResult.failure('Something went wrong!'); }); }
Only one task is permitted per program. However, that task can run any number of tests internally. A task has a name. It succeeds and fails independently of other tasks, and is reported to the dashboard independently of other tasks.
A task runs in its own standalone Dart VM and reports results via Dart VM service protocol. This ensures that tasks do not interfere with each other and lets the CI system time out and clean up tasks that get stuck.
The manifest.yaml file describes a subset of tests we run in the CI. To add your test edit manifest.yaml and add the following in the “tasks” dictionary:
{NAME_OF_TEST}:
description: {DESCRIPTION}
stage: {STAGE}
required_agent_capabilities: {CAPABILITIES}
Where:
{NAME_OF_TEST} is the name of your test that also matches the name of the file in bin/tasks without the .dart extension.{DESCRIPTION} is the plain English description of your test that helps others understand what this test is testing.{STAGE} is devicelab if you want to run on Android, or devicelab_ios if you want to run on iOS.{CAPABILITIES} is an array that lists the capabilities required of the test agent (the computer that runs the test) to run your test. As of writing, the available capabilities are: linux, linux/android, linux-vm, mac, mac/ios, mac/iphonexs, mac/ios32, mac-catalina/ios, mac-catalina/android, ios/gl-render-image, windows, windows/android.If your test needs to run on multiple operating systems, create a separate test for each operating system.