run_web_platform_tests.md

Running Web Platform Tests with run_wpt_tests.py

run_web_tests.py runs web tests with content shell through protocol mode. See web_tests.md for details. run_wpt_tests.py instead can run web platform tests with Chrome, Chrome Android and WebView. This document explains how to use run_wpt_tests.py in these scenarios.

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Difference and Similarity with run_web_tests.py

run_wpt_tests.py can run with different browsers. To specify which browser to run tests with, you should use --product or -p. Supported parameters are chrome, chrome_android (or clank), and android_webview (or webview). The default value is chrome if not specified.

The CLI is mostly kept the same between run_web_tests.py and run_wpt_tests.py. To see a complete list of arguments supported in run_wpt_tests.py, run:

third_party/blink/tools/run_wpt_tests.py --help

Running Web Platform Tests with Chrome

Note: Internal testing APIs, e.g. window.internals or window.testRunner, are not available in Chrome. Internal web platform tests using those APIs should be skipped through NeverFixTests.

Supported Platforms

• Linux

Test expectations and baselines are only actively maintained for Linux due to resource constraints. It's not yet possible to run tests for Chrome on non-Linux platforms; follow https://crbug.com/1512219 for status.

Initial Setup

Before you can run the web platform tests, you need to build the chrome_wpt_tests target to get chrome, chromedriver and all of the other needed binaries.

autoninja -C out/Default chrome_wpt_tests

Running the Tests

Once you have chrome and chromedriver built, running tests is very much similar to how you run tests with run_web_tests.py. For example, to run tests in external/wpt/html/dom, you should run:

third_party/blink/tools/run_wpt_tests.py --release -p chrome third_party/blink/web_tests/external/wpt/html/dom

Note: consider using -v to get browser logs. It can be provided multiple times to increase verbosity.

Test expectations and Baselines

The ChromeTestExpectations file contains the list of all known Chrome specific test failures, and it inherits or overrides test expectations from the default TestExpectations file. A special tag Chrome is introduced to specify chrome specific failures. See the Web Test Expectations documentation for more on this.

Chrome specific baselines reside at third_party/blink/web_tests/platform/linux-chrome, and falls back to third_party/blink/web_tests/platform/linux. To update baselines for chrome, you should trigger linux-wpt-chromium-rel and run rebaseline tool after the results are ready.

Running webdriver tests with Chrome

Webdriver tests are one type (wdspec) of web platform tests. Due to this you can run webdriver tests the same way as other web platform tests, e.g.

third_party/blink/tools/run_wpt_tests.py --release -p chrome external/wpt/webdriver/tests/classic/find_element/find.py

The webdriver_wpt_tests step of linux-blink-rel runs wdspec tests and can provide results for rebaselining.

Running Web Platform Tests with Chrome Android

To be updated.

Running Web Platform Tests with WebView

To be updated.

Debugging Support

Text-Based Debuggers

To interactively debug WPTs, prefix the run_wpt_tests.py command with debug_renderer to attach a debugger to a desired renderer.

For other use cases, see these debugging tips.

Known Issues

• Chromium's infrastructure currently tests WPTs against chrome --headless=old (i.e., the //headless layer, not //chrome). This may cause results to differ from wpt.fyi or content_shell --run-web-tests incorrectly. Notably, //headless will not apply features listed in fieldtrial_testing_config.json. See https://crbug.com/1485918 for updates on switching testing to chrome --headless=new for more useful results.

Please file bugs and feature requests against Blink>Infra with the wptrunner label.