Selectors Level 3 Conformance Test Suite

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This is a Development version of the Selectors Level 3 Conformance Test Suite.

You can provide test data or review the testing results for this test suite:

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Some tests in the test suite may contain errors. Please check the latest version of the Selectors 3 specification and its errata before assuming a failure is due to an implementation bug and not a test suite bug.

In time we hope to correct all errors and extend this test suite to cover all of Selectors 3. Your help is welcome in this effort. The appropriate mailing list for submitting tests and bug reports is More information on the contribution process and test guidelines is available on the wiki page.

Tests are currently available in these formats:

HTML 5 tests sent as text/html
XHTML 1.1 tests sent as application/xhtml+xml
XHTML 1.1 for Printers
XHTML 1.1 tests with all images converted from PNG to JPEG and formatted with headers and footers to ease testing of embedded printer software. This is not a canonical format, and some tests may fail due to the format conversion that would otherwise pass in the above XHTML 1.1 format.

Unless the test instructions explicitly indicate otherwise, any occurrence of red in a test indicates test failure.

Implementation Reports

An implementation report template is available to help with creating implementation reports. See also the explanation of its format.

Common Assumptions

Most of the test suite makes the following assumptions:

Uncommon Assumptions

In addition, some of the tests make one or more of the following assumptions:

The tests that need these assumptions to be true have not yet been marked, but it is likely that we will add a way to identify these tests in due course. Tests should avoid relying on these assumptions unless necessary.


This test suite is licensed under both the W3C Test Suite License and the W3C 3-clause BSD License. See W3C Legal's explanation of the licenses.


Many thanks to the following for their contributions: