Acid3

Infobox Website
name = Acid3



caption = The reference image for Acid3.
url = [http://acid3.acidtests.org/ http://acid3.acidtests.org]
commercial =
type = Web standards test
language = English language
registration =
owner = The Web Standards Project
author = Ian Hickson
launch date = March 3, 2008
current status =
revenue =
slogan =

Acid3 is a test page from the Web Standards Project that checks how well a web browser follows certain web standards, especially relating to the Document Object Model and JavaScript.

When successful, the Acid3 test displays a gradually increasing percentage counter with colored rectangles in the background. The percentage displayed is based on the number of sub-tests passed. In addition to these the browser also has to render the page exactly like the reference page as rendered in the same browser. Like the text of the Acid2 test the text of the reference rendering is not a bitmap in order to allow for certain differences in font rendering.

Acid3 was in development from April 2007, [cite web
url=http://krijnhoetmer.nl/irc-logs/whatwg/20070422#l-284
title=HTML5 IRC logs: freenode / #whatwg / 20070422
accessdate=2007-12-28] and released on 3 March 2008.cite web
url=http://www.webstandards.org/press/releases/20080303/
title=Acid3: Putting Browser Makers on Notice, Again. (WaSP Press Release)
accessdate=2007-03-04] The main developer was Ian Hickson, who also wrote the Acid2 test. Acid2 focused primarily on Cascading Style Sheets, but this third Acid test focuses also on technologies used on modern, highly interactive websites characteristic of Web 2.0, such as ECMAScript and DOM Level 2. A few tests also concern Scalable Vector Graphics (SVG), XML and . It includes several elements from W3C CSS3 working drafts that have not made it to candidate recommendations yet.

Name

Acid3 is a short for "Acid test #3". During the the gold rush of the 1850s, an acid test was a test designed to testify whether a given (excavated or found) metal is indeed gold.

Acid test was "the" test of the time, since it was decisive, immediate, cheap and extremely simple to perform. An analogy is drawn from this historical test to the modern test - if a browser passes the acid test it is approved, very much in the same manner that if a metal passes the acid test it is accepted.

The test

The main part of Acid3 is written in ECMAScript (JavaScript) and consists of 100 subtests in six groups called "buckets", including four special tests (0, 97, 98, and 99). [cite web
last=Hickson
first=Ian
url=http://acid3.acidtests.org/
title=Comments in the source code of the test page
accessdate=2008-02-16]
* Bucket 1: DOM Traversal, DOM Range, HTTP
* Bucket 2: DOM2 Core and DOM2 Events
* Bucket 3: DOM2 Views, DOM2 Style, CSS 3 selectors and [http://www.w3.org/TR/css3-mediaqueries/ Media Queries]
* Bucket 4: Behavior of HTML tables and forms when manipulated by script and DOM2 HTML
* Bucket 5: Tests from the Acid3 Competition (SVG, [cite web
last=Dahlström
first=Erik
date = 2008-01-22
url=http://my.opera.com/MacDev_ed/blog/2008/01/22/core-web
title=Getting to the core of the web
accessdate=2008-02-16] HTML, SMIL, Unicode, …)
* Bucket 6: ECMAScript

The compliance criteria requires that the test is run with a browser's default settings. The final rendering must have a 100/100 score and must not only be pixel-identical with the [http://acid3.acidtests.org/reference.html reference rendering] , including the favicon (or more accurately, its desired absence; a favicon is not supposed to show up in a 100/100 render), but the animation has to be smooth (taking no more than 33 ms for each subtest on the top-of-the-line Apple laptop) as well. [cite web | url = http://ln.hixie.ch/?start=1207096078&count=1 | title = The performance aspect of Acid3 | author = Ian Hickson | date = 2008-04-01 | accessdate = 2008-04-03]

As the test is run, rectangles are added to the rendered image; the color of the rectangles is decided by the number of sub-tests passed in the bucket. If all subtests fail in a particular bucket, its associated rendered rectangle will be invisible. If some subtests are cleared the color will change in four steps:
* 1-5 subtests passed: Black rectangle.
* 6-10 subtests passed: Grey rectangle.
* 11-15 subtests passed: Silver rectangle.
* All 16 subtests passed: Colored rectangle (red, orange, yellow, lime, blue, purple - for each of the six rectangles, respectively).

After the Acid3 test page is completely rendered, the capital A in the word Acid3 can be clicked to see an alert (or Shift-Click for a new window) explaining exactly which subtests have failed, and what the error message was.

In order to render the test correctly, user agents need to implement the [http://www.w3.org/TR/css3-text/#text-shadow CSS 3 Text Shadows] and the [http://www.w3.org/TR/css3-webfonts/#font-descriptions CSS 2.x Downloadable Fonts] specifications, which are currently under consideration by W3C to be standardized. This is required as the test uses a custom TrueType font, called "AcidAhemTest" to cover up an "X" on fuchsia colored background. The glyph, when rendered by the downloaded font, is just a square, made white with CSS, and thus invisible.Fact|date=March 2008

In addition, the test also uses Base64 encoded images, some more advanced selectors, CSS 3 color values ( [http://www.w3.org/TR/2003/CR-css3-color-20030514/#hsla-color HSLA] ) as well as bogus selectors and values that should be ignored.

Development and impact

Ian Hickson started working on the test in April 2007, but development progressed slowly. In December 2007, work restarted and the project received public attention on 10 January 2008, when it was mentioned in blogs by Anne van Kesteren [cite web
last=van Kesteren
first=Anne
date = 2008-01-10
url=http://annevankesteren.nl/2008/01/acid3
title=Acid3
accessdate=2008-03-04] and Dustin Brewer. [cite web
last=Brewer
first=Dustin
date = 2008-01-10
url=http://dustinbrewer.com/developers-are-working-on-acid3-test/
title=Developers are working on ACID3 test
accessdate=2008-03-04] At the time the project resided at a URL clearly showing its experimental nature: "http://www.hixie.ch/tests/evil/acid/003/NOT_READY_PLEASE_DO_NOT_USE.html" That did not stop the test from receiving widespread attention within the web development community. At that time only 84 subtests were done, and on 14 January Ian Hickson announced a competition to develop the missing 16. [cite web
last=Hickson
first=Ian
date = 2008-01-14
url=http://ln.hixie.ch/?start=1200301306&count=1
title=The competition for you to come up with the best test for Acid3
accessdate=2008-03-04]

The following developers contributed to the final test through this competition:
* Sylvain Pasche. Test 66–67 (DOM).
* David Chan. Test 68 (UTF-16/UCS-2).
* Simon Pieters (Opera) and Anne van Kesteren (Opera). Test 71: HTML parsing.
* Jonas Sicking (Mozilla) and Garrett Smith. Test 72: dynamic modification of style blocks' text nodes.
* Jonas Sicking (Mozilla). Test 73: Nested events.
* Erik Dahlström (Opera). Test 74–78: SVG and SMIL.
* Cameron McCormack. Test 79: SVG fonts.

Even before its official release, Acid3's impact on browser development was dramatic. WebKit in particular made progress; in less than a month their score rose from 60 to 87.cite web
last=Hickson
first=Ian
date = 2008-03-04
url=http://ln.hixie.ch/?start=1204593554&count=1
title=Moebius (announcement of the completion of the test)
accessdate=2008-03-04]

The test was officially released on March 3, 2008. A guide and commentary was expected to follow within a few months, however, as of September 2008 it has not yet been released. The announcement that the test is complete means only that it is to be considered "stable enough" for actual use; if problems and bugs are found, it will still be modified to fix it. The test has already been modified to fix several issues including issues regarding to sub-pixel positioning, SVG surrogate pairs and performance. [cite web | url = http://ln.hixie.ch/?start=1206565203&count=1 | title = Tests that are never quite finished | author = Ian Hickson | accessdate = 2008-03-30] On March 26, 2008—the day both Opera and WebKit teams announced a 100/100 score—developers of WebKit contacted main Acid3 developer Ian Hickson about a critical bug in the Acid3 that presumably may have forced a violation of the SVG 1.1 standard to pass; thus Hickson proceeded to fix it with the help of Cameron McCormack, member of W3C's SVG Working Group. [cite web |url=http://ln.hixie.ch/?start=1206578003&count=1 |title=Last minute changes to Acid3 |author=Ian Hickson |accessdate=2008-03-30] cite web |title=WebKit achieves Acid3 100/100 in public build |url=http://webkit.org/blog/173/webkit-achieves-acid3-100100-in-public-build/ |date=2008-03-26 |author=Maciej Stachowiak |accessdate=2008-03-26]

By the end of March 2008, early development versions of the Presto and WebKit layout engines scored 100/100 on the test and rendered the test page correctly.cite web
url=http://my.opera.com/desktopteam/blog/2008/03/26/opera-and-the-acid3-test
title=Opera and the Acid3 Test
author=Junyor
date= March 2008
accessdate=2008-03-28] cite web
url=http://labs.opera.com/news/2008/03/28/
title=Public Acid3 build | quote="The latest post-9.5 build scores 99/100 and fails the smoothness criterion."
author=Lars Erik Bolstad
date= March 2008
accessdate=2008-03-28] Presto still has performance issues in producing a smooth animation in the test, thus it has not passed the Acid3 test yet. As of build r36882, WebKit produces a smooth animation on the reference hardware, and thus passes the Acid3 testcite web
url=http://webkit.org/blog/280/full-pass-of-acid-3/
title=The latest WebKit development build scores 100/100, renders the test correctly, and passes the smoothness criterion] . Firefox developers had been preparing for the imminent release of Firefox 3, as a result they had focused on stability rather than passing the Acid3 test.cite web |url=http://shaver.off.net/diary/2008/03/27/the-missed-opportunity-of-acid-3/ |title=The missed opportunity of acid 3 |author=Mike Shaver |date=2008-03-27 |accessdate=2008-03-30] Microsoft, developers of the Internet Explorer browser, said that Acid3 does not map to the goal of Internet Explorer 8 and that IE8 will improve only some of the standards being tested by Acid3.cite web | url = http://www.microsoft.com/windowsxp/expertzone/chats/transcripts/08_0320_ez_ie8.mspx | title = Windows Internet Explorer 8 Expert Zone Chat (March 20, 2008) | author = Chris Wilson | quote = "The ACID3 test is a collection of interesting tests, spread across a large set of standards. Some of those standards will see improvements in IE8 - in fact, IE8 already improves on IE7's score - but we are focused on the most important features and standards to make web developers' lives easier. The ACID3 test does not map directly to that goal." | accessdate = 2008-04-15]

On April 22, 2008, Hickson again fixed a bug in the Acid3 test discovered by a Mozilla developer. This change possibly invalidates the previously reported scores of 100/100 for development versions of Presto and WebKit. [cite web |url=http://ln.hixie.ch/?start=1208832405&count=1 |title=Media queries and performance in Acid3 (and an error on my part) |author=Ian Hickson |date=2008-04-22 |accessdate=2008-04-24] On September 29, 2008, David Baron raised an issue with the CSS Working Group concerning media queries that might cause the test to change again. [cite web |url=http://lists.w3.org/Archives/Public/www-style/2008Sep/0218.html |title=should comma be an error handling recovery point? |author=David Baron |date=2008-09-29 |accessdate=2008-09-29]

Layout engines

Acid3 was deliberately written in such a way that every web browser failed the test at the time of its release. Many of the browser teams are actively working to improve test results.

Desktop browsers

WebSlice-begin|id=1|title=Acid3 Compliance UpdatesWebSlice-end

Mobile browsers

WebSlice-begin|id=3|title=Acid3 in mobile web browsers

ee also

* Comparison of layout engines

References

External links

* [http://acid3.acidtests.org/ The Acid3 Test]
* [http://acid3.acidtests.org/reference.html The Acid3 Test (Reference Rendering)]
* [http://www.webstandards.org/action/acid3/ The Acid3 test at Web Standards Project]
* [http://ln.hixie.ch/?start=1206565203&count=1 Post-release revisions to the Acid3 test]