The Internet Explorer 8 Release Candidate is the last major IE8 testing milestone. It indicates that we believe that IE8 is implementation complete for CSS 2.1. We also believe IE8 RC1 has the most complete implementation of the CSS 2.1 specification in the industry.
The only way to know if a browser has correctly implemented a specification is to develop a comprehensive set of tests for the specification. These can be used to determine both the support for a specific part of the spec and the behavior of a specific browser. Web developers can also use these test pages as examples of how to combine various layout properties and elements in their pages and know that their page will interoperate well across all the browsers that pass those tests.
Today, the IE Team is submitting 3784 new test cases to the CSS 2.1 Working Group for inclusion into the CSS 2.1 test suite. These cases were developed since IE8 Beta 2. This brings Microsoft’s contribution to the CSS 2.1 Test Suite to 7005 tests. IE8 RC1 passes all of these tests today. All but 52 of these cases also pass in at least one other major browser. We’re working closely with the CSS working group to swiftly include these in the official test suite. For now, these tests are available at the Windows Internet Explorer Testing Center. The last key element to web layout interoperability is actually passing the tests. IE8 RC1 is the first browser to pass all valid tests in the suite thus meeting the interoperability requirements in the 2.1 spec.
It’s important that the spec, the browser, and the tests all agree on a behavior. This is when web developers really win. While developing these test cases, we found instances where all other browsers implemented something a specific way. That syntax pattern was in pages all over the web, creating a broad dependency on that behavior. In those cases, we proposed a change to the spec and developed an associated test case to ensure the web continues to work and browsers can implement the spec as written. We sincerely hope this helps the committee finish the 2.1 spec and move it into the Recommendation phase.
There is also a variety of unofficial, unsanctioned “tests” posted around the web as well. These range from quirky web pages that someone developed to show off a bug in a browser to complex degenerative web scenarios that combine CSS 2.1 properties and elements in unlikely ways. Some of these are pragmatic tests that actually demonstrate a real-world situation where there are inconsistencies across major browsers. IE8 RC1 passes all of the pragmatic “tests” we could find, although new combinations can always be developed. I strongly encourage those test authors to submit their cases to the W3C’s CSS 2.1 test suite so those tests may be used by any browser under the W3C’s license. Only then will those tests broadly benefit web developers.
If you have specific feedback on any particular test case, I strongly encourage you to provide it on the W3C’s CSS 2.1 Working Group’s mailing list. That will ensure the test case reviewers have your comments in context as they add these pages into the suite.
Jason Upton Test Manager – Internet Explorer