First checked-in import of the W3C's test suites.

LayoutTests/imported/csswg-test/README.md

Index: LayoutTests/imported/csswg-test/README.md
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+W3C CSS Test Suite Repository
+-----------------------------
+ 
+This repository contains top level directories for all of CSS specs for
+which we currently have tests. Place tests in the appropriate directory based
+on the first rel="help" link in the test. If you are writing tests for a spec
+and it doesn't yet have a directory here, feel free to create it.
+
+There are a few directories that do not map to specifications:
+
+support/ contains common image files to which many of the tests link in
+this location
+
+tools/ is random scripts that may be useful when administering tests.
+
+vendor-imports/ is where third parties may import their tests that originate
+and are maintained in an external repo. Files in this directory should
+never be modified in this repo, but should go through the vendor's process
+to be imported here.
+
+work-in-progress/ is a legacy directory that contains all the work that was
+once submitted to the repo, but was not yet ready for review. Since the CSSWG
+has adopted the GitHub pull request process, no new files should be landed here.
+The subdirectories here are named by test author or contributing organization.
+
+Linking Your Tests to Specifications
+-----------------------------------
+
+In addition to placing your tests in the appropriate directory in this repository,
+you must also include at least one specification link in the test metadata,
+following [these guidelines][speclinks].
+
+For CSS tests, you must also be sure you’re linking to a specific level of the spec,
+generally the first level where the feature being tested is defined. Where possible,
+it’s preferable to link to the official version of the spec, which will start with
+http://www.w3.org/TR/. This can usually be found as the ‘Latest version’ link in the
+spec itself and will include the level of the spec in the URL. For example, the proper
+link to level 1 of the CSS Flexbox spec is:
+
+http://www.w3.org/TR/css-flexbox-1/#RELEVANT_SECTION
+
+When testing features not yet available in an official draft, link to the appropriate
+Editor’s Draft found at http://dev.w3.org/csswg/. Be sure to include the level of the
+specification in the link. For example, the proper link to the CSS Flexbox Level 1
+Editor’s Draft is:
+
+http://dev.w3.org/csswg/css-flexbox-1/#RELEVANT_SECTION
+
+Contributing
+-------------
+
+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][contributing]. 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.
+
+Write Access
+------------
+
+This section only applies if you have cloned the repository from
+Mercurial. If you've cloned it from GitHub, which is a mirror of
+the canonical Mercurial repo, you can submit your tests via a [pull request][github101].
+
+To gain write access to this Mercurial repository, sign up for an account
+on the CSS Test Suite Manager (aka Shepherd) at:
+https://test.csswg.org/shepherd/register
+and then submit a request on the Repository Access page at:
+https://test.csswg.org/shepherd/account/access/
+
+You will be notified by email when your request is processed.
+
+Please note that although we will grant write access directly to the Mercurial
+repo, it is strongly advised to use GitHub for test submissions to enable
+reviewers to use its built-in review tools. Direct submissions to Mercurial
+should be limited to administrative or housekeeping tasks, very minor changes
+that don't require a review, or from advanced users of the system.
+
+[contributing]: https://github.com/rhauck/csswg-test/blob/master/CONTRIBUTING.md
+[github101]: http://testthewebforward.org/docs/github-101.html
+[speclinks]: http://testthewebforward.org/docs/test-templates.html#specification-links