Acid2

Initiated by Håkon Wium Binds and supported by in [[Web Project Standards]] (WASP), the test Acid2 aims at testing the quality of the implementation of a choice of functionalities related to different Standards from the Web in a navigator, considered to be priority by its promoters. It was named thus in reference to a first in acid historical test, created by in Tod Fahrner, which related to the model of box CS 1, and which had been integrated thereafter in “in Test continuation for Cascading Style Sheets (CSS) Level 1” of W3C

Historical context

In March 2005, Håkon Wium Binds, chief technical officer of Opera Software and creator of the Style sheet in cascade, announces the nearest publication of a test of compatibility relating to functionalities whose support would be particularly claimed by the developers of Web sites. This advertisement makes following the decision of Microsoft start again the development of sound Navigateur Web Internet Explorer, stopped, except update of safety, since its version 6.0 in 2001. Acid2 is then openly presented like a challenge launched at Microsoft, shown up to that point not to have held its promises interworking implementation of the Standards of the Web.

This polemical aspect of the test causes reserves on behalf of other experts participating in the development and the promotion of the standards of the Web, such as Eric Meyer. The Acid2 test is finally presented by in WASP like being addressed to the whole of the navigators Web.

The passage of the Acid2 test was not retained by Microsoft like a relevant priority during the development of Internet Explorer 7: Chris Wilson, person in charge of the development of IE, declares indeed as of July 2005:

As a list of wishes, acid2 is really important and useful for my team. But it is not intended to have, in my opinion, priority for IE7.

Nous let us admit perfectly that IE is except play today because of its support CS. We traversed the Acid2 test, and we analyzed in detail the problems encountered by IE. We registered these bugs and these functionalities on our list. However, they are functionalities complex and difficult to implement, and they will not be top of the list for IE7. I think that we will render a much better service to the Web developers by solving our bugs initially more the headaches for them, our problems of utilisability and by giving the priority to the functionality most often asked, starting from the returns that we had.

In fact, the final version of Internet Explorer 7 in 2006 corrects a number important of bugs CS not entering the field of the Acid2 test. These bugs had been highlighted by independent Web developers joined together in particular around the sites in Position is Everything , in QuirksMode and of satzansatz . The WASP had played itself besides a big role in the exchanges between these private initiatives and Microsoft.

Summary description of the test

With the difference in the tests of conformity usually used for the implementations HTML or CS, Acid2 is not a succession of unit tests: it is appeared as a single Web page which concentrates several tens of tests, in the shape of a drawing made up of coloured horizontal lines representing a smiling figure. In spite of the furnished documents, it results a certain complexity from it, requiring later precise details on the specific tests.

The only text present is in “Hello World! ” like two mentions in “ERROR”. Beaconing HTML4.01 is a series of generic blocks (elements div) or specific (elements h2, p, object, table, blockquote, address and lists ul) for the majority vacuums.

The Style sheet intern combines various series of properties, so as to test the support:

of relative, absolute positioning and fixes
model of box
of the model of formattage in table
of the calculation algorithm of the margins
of the contents generated
of the calculation row heights in the boxes of line
of the behavior at the overflight
about the drawing in stackings
of the rules of in [[syntactic Analysis parsing]] CS.

The test is not limited to test functionalities of CS 2. It also relates to the support of overlapping elements object, making it possible to produce various alternate contents according to the capacities of the customer, as well as the rules of in parsing HTML on the closing of the beacons and the blocks of comments SGML. It checks finally the support of the translucent images png and the correct management of the protocol data: for the insertion of integrated objects.

The functionalities checked by the Acid2 test are intended to be implemented by the navigators Web in mode of made “strict”: the technique of in doctype switching enables them to maintain if necessary their former implementations, nonin conformity, in their mode of made compatible (mode “quirks”).

If the result of the posting of this Web page is not identical to the awaited drawing, the placement of CS 2 in the navigator is theoretically not in conformity with the specification CS 2. On the other hand, the fact that a navigator makes a success of the test does not mean that it entirely supports CS 2.

Navigators passing the test successfully

The navigators based on WebKit were the first to successfully pass this test in their versions of development, thanks to the work of David Hyatt, principal developer of Safari. They were followed rather quickly by ICab, another navigator for Mac OS X not using WebKit, and by KHTML (Konqueror) benefitting from its relationship with WebKit.

Opera made a success of the test in its version 9.0. Mozilla Firefox makes a success of it in version of development since the “ nightly ” of December 8th, 2006.

References

Random links: