When a new browser standard like this is introduced, it is important that all implementers work hard to make sure that they correctly implement the standard and are compatible with each other. Language specifications are complex technical documents and even well written specification can be misinterpreted by implementers leading to incompatibles and interoperability issues.
One way to avoid this is for implementers to use a common specification compliance test suite. At the ECMA TC39 meeting this May, Microsoft announced that it was working on such test suite and made a preliminary version available to the ECMA members. We have now turned development of this test suite into a community development project hosted on Codeplex. This project is released as using the new BSD open source license and will be coordinated by TC39 members including Microsoft. Currently the test suite includes about 900 tests that mostly focus features that are new to ECMAScript 5. This is a small fraction of the tests that will be needed to provide complete conformance coverage for the entire language. Microsoft plans on continuing to contribute additional tests to the suite and we are working with other ECMA TC39 members to coordinate with any test suite development they may be doing.
Anyone who has the interest and skills for developing individual ECMAScript conformance tests are invited to participate in the project. If you’re interested check out the Codeplex site and get involved.
Microsoft TC-39 Representative