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diff --git a/testing/web-platform/docs/index.rst b/testing/web-platform/docs/index.rst new file mode 100644 index 0000000000..7f2d263113 --- /dev/null +++ b/testing/web-platform/docs/index.rst @@ -0,0 +1,375 @@ +web-platform-tests +================== + +`web-platform-tests <http://web-platform-tests.org>`_ is a +cross-browser testsuite. Writing tests as web-platform-tests helps +ensure that browsers all implement the same behaviour for web-platform +features. + +Upstream Documentation +---------------------- + +This documentation covers the integration of web-platform-tests into +the Firefox tree. For documentation on writing tests, see +`web-platform-tests.org <http://web-platform-tests.org>`_. In particular +the following documents cover common test-writing needs: + +* `Javascript Tests (testharness.js) + <https://web-platform-tests.org/writing-tests/testharness.html>`_ + + - `testharness.js API + <https://web-platform-tests.org/writing-tests/testharness-api.html>`_ + + - `testdriver.js API + <https://web-platform-tests.org/writing-tests/testdriver.html>`_ - + features for writing tests that require special privileges + e.g. user-initiated input events. + + - `Message Channels + <https://web-platform-tests.org/writing-tests/channels.html>`_ - + features for communicating between different globals (including + those in different browsing context groups / processes). + +* `Reftests <https://web-platform-tests.org/writing-tests/reftests.html>`_ + +* `Crashtests <https://web-platform-tests.org/writing-tests/crashtest.html>`_ + +* `Server features + <https://web-platform-tests.org/writing-tests/server-features.html>`_ - + e.g. multiple origins, substitutions, server-side Python scripts. + +Running Tests +------------- + +Tests can be run using ``mach``:: + + mach wpt + +To run only certain tests, pass these as additional arguments to the +command. For example to include all tests in the dom directory:: + + mach wpt testing/web-platform/tests/dom + +Tests may also be passed by id; this is the path plus any query or +fragment part of a URL and is suitable for copying directly from logs +e.g. on treeherder:: + + mach wpt /web-nfc/idlharness.https.window.html + +A single file can produce multiple tests, so passing test ids rather +than paths is sometimes necessary to run exactly one test. + +The testsuite contains a mix of various test types including +Javascript (``testharness``) tests, reftests and wdspec tests. To limit +the type of tests that get run, use ``--test-type=<type>`` e.g. +``--test-type=reftest`` for reftests. + +Note that if only a single testharness test is run the browser will +stay open by default (matching the behaviour of mochitest). To prevent +this pass ``--no-pause-after-test`` to ``mach wpt``. + +When the source tree is configured for building android, tests will +also be run on Android, by default using a local emulator. + +Running Tests In Other Browsers +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +web-platform-tests is cross browser, and the runner is compatible with +multiple browsers. Therefore it's possible to check the behaviour of +tests in other browsers. By default Chrome, Edge and Servo are +supported. In order to run the tests in these browsers use the +``--product`` argument to wptrunner:: + + mach wpt --product chrome dom/historical.html + +By default these browsers run without expectation metadata, but it can +be added in the ``testing/web-platform/products/<product>`` +directory. To run with the same metadata as for Firefox (so that +differences are reported as unexpected results), pass ``--meta +testing/web-platform/meta`` to the mach command. + +Results from the upstream CI for many browser, including Chrome and +Safari, are available on `wpt.fyi <https://wpt.fyi>`_. There is also a +`gecko dashboard <https://jgraham.github.io/wptdash/>`_ which by default +shows tests that are failing in Gecko but not in Chrome and Safari, +organised by bug component, based on the wpt.fyi data. + +Directories +----------- + +Under ``testing/web-platform`` are the following directories: + +``tests/`` + An automatically-updated import of the web-platform-tests + repository. Any changes to this directory are automatically + converted into pull requests against the upstream repository, and + merged if they pass CI. + +``meta/`` + Gecko-specific metadata including expected test results + and configuration e.g. prefs that are set when running the + test. This is explained in the following section. + +``mozilla/tests`` + Tests that will not be upstreamed and may + make use of Mozilla-specific features. They can access + the ``SpecialPowers`` APIs. + +``mozilla/meta`` + Metadata for the Mozilla-specific tests. + +Metadata +-------- + +In order to separate out the shared testsuite from Firefox-specific +metadata about the tests, all the metadata is stored in separate +ini-like files in the ``meta/`` sub-directory. + +There is one metadata file per test file with associated +gecko-specific data. The metadata file of a test has the same relative +path as the test file and has the the suffix ``.ini`` e.g. for the +test in ``testing/web-platform/tests/example/example.html``, the +corresponding metadata file is +``testing/web-platform/meta/example/example.html.ini``. + +The format of these files is similar to `ini` files, but with a couple +of important differences; sections can be nested using indentation, +and only `:` is permitted as a key-value separator. For example:: + + [filename.html] + [Subtest 1 name] + key: value + + [Subtest 2 name] + key: [list, value] + +For cases where a single file generates multiple tests (e.g. variants +or ``.any.js`` tests), the metadata file has one top-level section for +each test, for example:: + + [test.any.html] + [Subtest name] + key: value + + [test.any.worker.html] + [Subtest name] + key: other-value + +Values can be made conditional using a Python-like conditional syntax:: + + [filename.html] + key: + if os == "linux": linux-value + default-value + +The available variables for the conditions are those provided by +`mozinfo +<https://firefox-source-docs.mozilla.org/mozbase/mozinfo.html>`_, plus +some additional `wpt-specific values +<https://searchfox.org/mozilla-central/search?q=def%20run_info_extras&path=testing%2Fweb-platform%2Ftests%2Ftools%2Fwptrunner%2Fwptrunner%2Fbrowsers%2Ffirefox.py&case=false®exp=false>`_. + +For more information on manifest files, see the `wptrunner +documentation +<https://web-platform-tests.org/tools/wptrunner/docs/expectation.html>`_ + + +Expectation Data +~~~~~~~~~~~~~~~~ + +All tests that don't pass in our CI have expectation data stored in +the metadata file, under the key ``expected``. For example the +expectation file for a test with one failing subtest and one erroring +subtest might look like:: + + [filename.html] + [Subtest name for failing test] + expected: FAIL + + [Subtest name for erroring test] + expected: ERROR + +Expectations can be made configuration-specific using the conditional syntax:: + + [filename.html] + expected: + if os == "linux" and bits == 32: TIMEOUT + if os == "win": ERROR + FAIL + +Tests that are intermittent may be marked with multiple statuses using +a list of possibilities e.g. for a test that usually passes, but +intermittently fails:: + + [filename.html] + [Subtest name for intermittent test] + expected: [PASS, FAIL] + + +Auto-generating Expectation Data +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +After changing some code it may be necessary to update the expectation +data for the relevant tests. This can of course be done manually, but +tools are available to automate much of the process. + +First one must run the tests that have changed status, and save the +raw log output to a file:: + + mach wpt /url/of/test.html --log-wptreport wptreport.json + +Then the ``wpt-update`` command may be run using this log data to update +the expectation files:: + + mach wpt-update wptreport.json + +CI runs also produce ``wptreport.json`` files that can be downloaded +as artifacts. When tests are run across multiple platforms, and all +the wptreport files are processed together, the tooling will set the +appropriate conditions for any platform-specific results:: + + mach wpt-update logs/*.json + +For complete runs the ``--full`` flag will cause metadata to be +removed when a) the test was updated and b) there is a condition that +didn't match any of the configuration in the input files. + +When tests are run more than once ``--update-intermittent`` flag will +cause conflicting results to be marked as intermittents (otherwise the +data is not updated in the case of conflicts). + +Disabling Tests +~~~~~~~~~~~~~~~ + +Tests are disabled using the same manifest files used to set +expectation values. For example, if a test is unstable on Windows, it +can be disabled using an ini file with the contents:: + + [filename.html] + disabled: + if os == "win": https://bugzilla.mozilla.org/show_bug.cgi?id=1234567 + +For intermittents it's generally preferable to give the test multiple +expectations rather than disable it. + +Fuzzy Reftests +~~~~~~~~~~~~~~ + +Reftests where the test doesn't exactly match the reference can be +marked as fuzzy. If the difference is inherent to the test, it should +be encoded in a `meta element +<https://web-platform-tests.org/writing-tests/reftests.html#fuzzy-matching>`_, +but where it's a Gecko-specific difference it can be added to the +metadata file, using the same syntax:: + + [filename.html] + fuzzy: maxDifference=10-15;totalPixels=200-300 + +In this case we expect between 200 and 300 pixels, inclusive, to be +different, and the maximum difference in any RGB colour channel to be +between 10 and 15. + + +Enabling Prefs +~~~~~~~~~~~~~~ + +Some tests require specific prefs to be enabled before running. These +prefs can be set in the expectation data using a ``prefs`` key with a +comma-separated list of ``pref.name:value`` items:: + + [filename.html] + prefs: [dom.serviceWorkers.enabled:true, + dom.serviceWorkers.exemptFromPerDomainMax:true, + dom.caches.enabled:true] + +Disabling Leak Checks +~~~~~~~~~~~~~~~~~~~~~ + +When a test is imported that leaks, it may be necessary to temporarily +disable leak checking for that test in order to allow the import to +proceed. This works in basically the same way as disabling a test, but +with the key ``leaks``:: + + [filename.html] + leaks: + if os == "linux": https://bugzilla.mozilla.org/show_bug.cgi?id=1234567 + +Per-Directory Metadata +~~~~~~~~~~~~~~~~~~~~~~ + +Occasionally it is useful to set metadata for an entire directory of +tests e.g. to disable then all, or to enable prefs for every test. In +that case it is possible to create a ``__dir__.ini`` file in the +metadata directory corresponding to the tests for which you want to +set this metadata e.g. to disable all the tests in +``tests/feature/unsupported/``, one might create +``meta/feature/unsupported/__dir__.ini`` with the contents:: + + disabled: Feature is unsupported + +Settings set in this way are inherited into sub-directories. It is +possible to unset a value that has been set in a parent using the +special token ``@Reset`` (usually used with prefs), or to force a value +to true or false using ``@True`` and ``@False``. For example to enable +the tests in ``meta/feature/unsupported/subfeature-supported`` one might +create an ini file +``meta/feature/unsupported/subfeature-supported/__dir__.ini`` like:: + + disabled: @False + +Setting Metadata for Release Branches +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Run info properties can be used to set metadata for release branches +that differs from nightly (e.g. for when a feature depends on prefs +that are only set on nightly), for example:: + + [filename.html] + expected: + if release_or_beta: FAIL + +Note that in general the automatic metadata update will work better if +the nonstandard configuration is used explicitly in the conditional, +and placed at the top of the set of conditions, i.e. the following +would cause problems later:: + + [filename.html] + expected: + if nightly_build: PASS + FAIL + +This is because on import the automatic metadata updates are run +against the results of nightly builds, and we remove any existing +conditions that match all the input runs to avoid building up stale +configuration options. + +Test Manifest +------------- + +web-platform-tests use a large auto-generated JSON file as their +manifest. This stores data about the type of tests, their references, +if any, and their timeout, gathered by inspecting the filenames and +the contents of the test files. It is not necessary to manually add +new tests to the manifest; it is automatically kept up to date when +running `mach wpt`. + +Synchronization with Upstream +----------------------------- + +Tests are automatically synchronized with upstream using the `wpt-sync +bot <https://github.com/mozilla/wpt-sync>`_. This performs the following tasks: + +* Creates upstream PRs for changes in + ``testing/web-platform/tests`` once they land on autoland, and + automatically merges them after they reach mozilla-central. + +* Runs merged upstream PRs through gecko CI to generate updated + expectation metadata. + +* Updates the copy of web-platform-tests in the gecko tree with + changes from upstream, and the expectation metadata required to make + CI jobs pass. + +The nature of a two-way sync means that occasional merge conflicts and +other problems. If something isn't in sync with upstream in the way +you expect, please ask on `#interop +<https://chat.mozilla.org/#/room/#interop:mozilla.org>`_ on matrix. |