W3C CSS3 Selectors Test Suite Index

The tests are available in several variants.

A list of recent changes may be found in the CHANGES file.

An implementation report template and instructions are available to help with creating an implementation report. Submitted implementation reports are available in the reports folder.

The Role Of This Test Suite

The role of this test is primarily to help implementors develop more comprehensive tests and to help authors gauge the level of support for the basics of the Selectors specification.

It is also a key part of the Selectors specification exit criteria. For this specification to exit the CR stage, the following conditions shall be met:

  1. There must be at least two interoperable implementations for every feature in the Selectors Module.

    For the purposes of this criterion, we define the following terms:


    a section or subsection in the Selectors Module.


    passing the respective test case(s) in the Selectors Module test suite, or, if the implementation is not a web browser, an equivalent test. Every relevant test in the test suite should have an equivalent test created if such a UA is to be used to claim interoperability. In addition if such a UA is to be used to claim interoperability, then there must one or more additional UAs which can also pass those equivalent tests in the same way for the purpose of interoperability. The equivalent tests must be made publically available for the purposes of peer review.


    a user agent which:

    1. implements the feature.
    2. is available (i.e. publicly downloadable or available through some other public point of sale mechanism). This is the "show me" requirement.
    3. is shipping (i.e. development, private or unofficial versions are insufficient).
    4. is not experimental (i.e. is intended for a wide audience and could be used on a daily basis.)
  2. A minimum of six months of the CR period must have elapsed. This is to ensure that enough time is given for any remaining major errors to be caught.


The authors of the test suite are Daniel Glazman, Ian Hickson and Lachlan Hunt.