How do you determine critical areas to test when verifying multiple browser support?

Question

With Microsoft putting out a new version of IE every year or so, competitors like Google Chrome, Firefox, and Safari also doing the same, there are questions, frequently, as to whether a web application supports a particular browser.

There is already a question out there (What techniques are available to determine which browsers to test?) on determining which browser to test. However, I've found in my experience that the rendering of the presentation layer has been of primary importance for testing browser support and the code that happens behind the scenes VERY rarely has any dependency on browser (if it does, that would seem to me to be a problem in design).

As the answer may vary based upon the application and design, how would you make a determination of what would "trigger" a browser check?

Answer 1

To decide what we need to test we need to understand what is likely to break. The current batch of web browsers have a set of commonly known bugs and differences. If you understand these differences, you can go a long way to understanding why pages have javascript issues or render differently in different browsers. Internet explorer has a large number of CSS layout issues and rendering bugs. A full list is available here.

Some minor rendering differences are expected from browser to browser, or within different versions of the same browser on different platforms.

The image below shows the rendering differences between Internet explorer 5.5 (which is ghosted) and Internet Explorer 6 for Microsoft’s homepage, back in 2008 when I first did the comparison.

What you can clearly see is that the main page elements in IE5.5 are clearly moved to the left. You can also see that the navigation bar is not working at all, and that silverlight is not supported on IE 5.5.

These types of rendering differences will occur typically across major versions of browsers. When a browser exists cross platform, the same rendering engine is typically used on all, so the same version of the same browser will typically render the same result on all platforms that it supports. This reduces the need for testing the same version of a browser on multiple platforms, however simple sanity checking of browsers cross platform is recommended if the configuration is already available.

You can see visually how these bugs manifest themselves with the Acid 2 test. This is a test that is designed to see if a browser can render CSS correctly. Most sites are typically tested on one main browser first (the market leader), and as a result, browsers that don’t have these issues, will now have layout issues. This is clearly shown below in this comparison of different browsers running the browser Acid 2 test.

If your sites are developed on Macs, you can almost guarantee there will be issues in Internet Explorer. If your site is developed on Windows 7, the opposite applies and Safari, and IE6 will probably be broken.

Also, a site will never look the same in EVERY browser. It is simply not possible. Here is how microsoft.com looks in lynx.

Ironically, this is exactly how search engines see the world.

Answer 2

Critical areas for browser compatibility checks are missing functionalities due to lack of support for javascript in the specific browser. It should also take into account the GUI issues like misalignment.

Some of the browsers may not support Javascript or Active-X control which are required by the software to provide the desired functionality to the end-user. See the following wikipedia article http://en.wikipedia.org/wiki/Comparison_of_web_browsers#JavaScript_support

For example:
1.) The date input field is validated for incorrect date-formats using javascript. If javascript is not supported by the browser, the software will allow the customer to enter invalid date which is a defect

2.) A country drop-down is sorted alphabetically using a client-side javascript. The same rule applies as one. If it is not supported, the user finds it very difficult to select a country from the dropdown

Text, graphics and color can appear differently on different browsers.
1.) Misalignment of controls on the web page which looks frustrating to the customer

2.) Web page looking cluttered on mobile browsers

Answer 3

There are different domains where browsers behave diffently:

• Javascript, as explained by Aruna
• plain HTML, like all version of IE before 9 not supporting the canvas tag
• CSS : for example, the support of CSS vary even between the different versions of IE http://www.smashingmagazine.com/2009/10/14/css-differences-in-internet-explorer-6-7-and-8/
• New HTML 5 related features, like the support of videos (with the now infamous WebM - H.264 war), the support of WebGL, WebFonts, SVG and so on...

The critical features you have to look at while testing depends greatly on your application and which features are used in it.