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Test Suites for Web Platform specifications
HTML JavaScript Python Other
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2dcontext Submit the remaining 2dcontext reftests to wpt.
DOMEvents Merge pull request #1646 from Ms2ger/reenter
FileAPI Fix test of Blob.length
IndexedDB IndexedDB: Explain magic numbers for version
WebCryptoAPI Add a test for passing float typed arrays to getRandomValues.
WebIDL fixup! Rewrite the exception tests in idlharness by specialized tests…
XMLHttpRequest Add missing done() call in send-usp.worker.
ambient-light Do not use non-standard flag argument of String.prototype.replace in …
animation-timing cancelAnimationFrame does nothing
app-uri Remove stale copies of testharness.js.
battery-status Improve unplugging tests for Battery Status API
common Move failing-test.html out of common.
conformance-checkers [cc] Updated the messages.json file.
content-security-policy CSP: Asterisk (*) wildcard should not allow blob:, data:, or filesyst…
cors fixup! Fix a CORS test to work with https support
csp Mozilla CSP tests
custom-elements Test that changing the value of the is attribute does not affect this…
docs typos in doc
dom Merge pull request #1773 from nox/splittext
domparsing Address review comments
domxpath Fix tests that have duplicate names.
encoding Merge pull request #1675 from inexorabletash/inexorabletash/encoding-…
eventsource Disallow tabs in eventsource.
ext-xhtml-pubid/the-xhtml-syntax/parsing-xhtml-documents Convert files with only CRLF line endings to pure LF
fetch/nosniff Address nits from @mikewest
fonts move hierarchy to the root
gamepad Add some basic manual tests and an idlharness test for Gamepad API.
geolocation-API Merge pull request #348 from zqzhang/submission/zqzhang/geo-idl-test-…
hr-time Removed trailing whitespaces and tabs. Removed webperf specs from lin…
html-imports HTML Imports: Add a case for "Fetching import" section.
html-longdesc Remove implementation reports.
html-media-capture Make assertion more common about data storage
html Remove tabs from html/syntax/.
http Add a test for respecting the HTTP content length header.
images Merge pull request #293 from onlimii/submission/jcxia-fileapi-url
infrastructure Move failing-test.html out of common.
js/builtins Merge pull request #1252 from iseki-masaya/masaya/preventExtensions
media-source Remove the timeout calls from media-source tests.
media add cross-origin accessible subtitle example
mediacapture-streams Fix error name 'PermissionDeniedError'
microdata Remove all manifest files from subdirectories
navigation-timing Removed trailing whitespaces and tabs. Removed webperf specs from lin…
notifications Added very basic tests of Notification instance.
old-tests/submission Make slow-loading script even slower
page-visibility Removed trailing whitespaces and tabs. Removed webperf specs from lin…
performance-timeline Address review comments on the Performance Timeline tests.
pointerevents Rewrite pointerevent_constructor to avoid the explicit_done.
pointerlock Revolves
progress-events Move the test for cross-origin progress events into place.
proximity Do not use non-standard flag argument of String.prototype.replace in …
quirks-mode Add more tests for :active/:hover quirk
referrer-policy Referrer-Policy: Add generated test files.
resource-timing Make resource timing test more debuggable and more robust to timing d…
resources @ 44bc39e Update resources.
selectors-api/tests/submissions/Opera Merge pull request #1560 from w3c/matches
selectors/attribute-selectors/attribute-case Use an actually-really-invalid selector for the invalid selector sani…
service-workers Make all CacheStorage tests use long timeout due to variable disk lat…
shadow-dom Merge pull request #1572 from w3c/jgraham/reftest_match
subresource-integrity whitespace
tools @ ab49e93 Update to latest wpt-tools
touch-events fix undefined function check_starting_element
typedarrays Merge pull request #1106 from zqzhang/zqzhang/manifest-remove
url Remove tabs from url/.
user-timing Removed trailing whitespaces and tabs. Removed webperf specs from lin…
vibration Remove a tab from vibration/.
web-animations Update AnimationTimeline and DocumentTimeline idl
webaudio WebAudio: Fix for WaveShaper "huge curve" test
webdriver Merge pull request #1328 from dannin/master
webgl Remove all manifest files from subdirectories
webmessaging Let some ports tests time out like normal
webrtc Ensure test passes in Firefox.
websockets Use a test per event type in a WebSocket events test.
webstorage Updated the IDL interfaces of WebStorage
webvtt fixup! Fix reftests missing rel=match excluding webvtt tests.
workers Merge pull request #1778 from Ms2ger/terminate
.gitignore Support running tests with SSL.
.gitmodules Move the tools directory into its own repo.
.travis.yml Try to ensure that travis has all submodules. Further modifications to the CLA text.
LICENSE actual license Update README file.
config.default.json Work around OpenSSL issues on windows
lint Update manifest to support reftest chains.
lint.whitelist Disallow tabs in eventsource.
manifest Make sure we supply the correct test root when generating the manifest.
serve Pass routes in to servers rather than relying on global state. Pass routes in to servers rather than relying on global state. Make tests self-hosting
testharness_runner.html Add testharness_runner file here for now.

The Web Platform Tests Project IRC chat

The Web Platform Tests Project is a W3C-coordinated attempt to build a cross-browser testsuite for the Web-platform stack. Writing tests in a way that allows them to be run in all browsers gives browser projects confidence that they are shipping software that is compatible with other implementations, and that later implementations will be compatible with their implementations. This in turn gives Web authors/developers confidence that they can actually rely on the Web platform to deliver on the promise of working across browsers and devices without needing extra layers of abstraction to paper over the gaps left by specification editors and implementors.

Running the Tests

The tests are designed to be run from your local computer. The test environment requires Python 2.7+ (but not Python 3.x). You will also need a copy of OpenSSL. Users on Windows should read the Windows Notes section below.

To get the tests running, you need to set up the test domains in your hosts file. The following entries are required:   web-platform.test   www.web-platform.test   www1.web-platform.test   www2.web-platform.test   xn--n8j6ds53lwwkrqhv28a.web-platform.test   xn--lve-6lad.web-platform.test

Because web-platform-tests uses git submodules, you must ensure that these are up to date. In the root of your checkout, run:

git submodule update --init --recursive

The test environment can then be started using


This will start HTTP servers on two ports and a websockets server on one port. By default one web server starts on port 8000 and the other ports are randomly-chosen free ports. Tests must be loaded from the first HTTP server in the output. To change the ports, edit the config.json file, for example, replacing the part that reads:

"http": [8000, "auto"]

to some port of your choice e.g.

"http":[1234, "auto"]

If you installed OpenSSL in such a way that running openssl at a command line doesn't work, you also need to adjust the path to the OpenSSL binary. This can be done by adding a section to config.json like:

"ssl": {"openssl": {"binary": "/path/to/openssl"}}

Windows Notes

Running wptserve with SSL enabled on Windows typically requires installing an OpenSSL distribution. Shining Light provide a convenient installer that is known to work, but requires a little extra setup.

After installation ensure that the path to OpenSSL is on your %Path% environment variable.

Then set the path to the default OpenSSL configuration file (usually something like C:\OpenSSL-Win32\bin\openssl.cfg in the server configuration. To do this copy config.default.json in the web-platform-tests root to config.json. Then edit the JSON so that the key ssl/openssl/base_conf_path has a value that is the path to the OpenSSL config file.

Test Runner

There is a test runner that is designed to provide a convenient way to run the web-platform tests in-browser. It will run testharness.js tests automatically but requires manual work for reftests and manual tests.

The runner can be found at /tools/runner/index.html on the local server i.e.


in the default configuration. The first time you use this it has to generate a manifest of all tests. This may take some time, so please be patient.


The master branch is automatically synced to

Pull requests that have been checked are automatically mirrored to

Finding Things

Each top-level directory represents a W3C specification: the name matches the shortname used after the canonical address of the said specification under .

For some of the specifications, the tree under the top-level directory represents the sections of the respective documents, using the section IDs for directory names, with a maximum of three levels deep.

So if you're looking for tests in HTML for "The History interface", they will be under html/browsers/history/the-history-interface/.

Various resources that tests depend on are in common, images, and fonts.

If you're looking at a section of the specification and can't figure out where the directory is for it in the tree, just run:

node tools/scripts/id2path.js your-id


In the vast majority of cases the only upstream branch that you should need to care about is master. If you see other branches in the repository, you can generally safely ignore them.


Save the Web, Write Some Tests!

Absolutely everyone is welcome (and even encouraged) to contribute to test development, so long as you fulfill the contribution requirements detailed in the Contributing Guidelines. No test is too small or too simple, especially if it corresponds to something for which you've noted an interoperability bug in a browser.

The way to contribute is just as usual:

  • Fork this repository (and make sure you're still relatively in sync with it if you forked a while ago).
  • Create a branch for your changes: git checkout -b your-name/topic.
  • Make your changes.
  • Run the lint script described below.
  • Commit locally and push that to your repo.
  • Send in a pull request based on the above.

A lint is available to test for common mistakes in testcases. It can be run with:


in the root of the checkout. It is also run for every submitted pull request, and branches with lint errors will not get merged. In the unusual case that the lint is reporting an error for something that is essential to your test, there is a whitelist at tools/lint/lint.whitelist that may be updated.

Adding command-line scripts ("tools" subdirs)

Sometimes you may want to add a script to the repository that's meant to be used from the command line, not from a browser (e.g., a script for generating test files). If you want to ensure (e.g., for security reasons) that such scripts won't be handled by the HTTP server, but will instead only be usable from the command line, then place them in either:

  • the tools subdir at the root of the repository, or

  • the tools subdir at the root of any top-level directory in the repository which contains the tests the script is meant to be used with

Any files in those tools directories won't be handled by the HTTP server; instead the server will return a 404 if a user navigates to the URL for a file within them.

If you want to add a script for use with a particular set of tests but there isn't yet any tools subdir at the root of a top-level directory in the repository containing those tests, you can create a tools subdir at the root of that top-level directory and place your scripts there.

For example, if you wanted to add a script for use with tests in the notifications directory, create the notifications/tools subdir and put your script there.

Test Review

We can sometimes take a little while to go through pull requests because we have to go through all the tests and ensure that they match the specification correctly. But we look at all of them, and take everything that we can.

Getting Involved

If you wish to contribute actively, you're very welcome to join the mailing list (low traffic) by signing up to our mailing list. The mailing list is archived.

Join us on irc #testing (, port 6665). The channel is archived.


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