Working across environments.
WHAT VARIES
Browsers and their versions Operating systems Devices and screen sizes Network conditions Installed extensions and blockers
WHAT TO ESTABLISH
What your users actually use.
HOW
Analytics, reviewed periodically.
WHAT TO SUPPORT
What a meaningful proportion of users have.
WHAT TO TEST ON
The most used, plus the oldest supported.
WHY THE OLDEST
It is where features silently fail.
WHAT COMMONLY DIFFERS BETWEEN BROWSERS
Date and number formatting Form control behaviour Newer language and interface features Font rendering
WHAT TO TEST ABOUT EXTENSIONS
Behaviour with content blockers, which are widely used.
WHY
They can break functionality entirely, and the user will not know why.
WHAT TO TEST ABOUT SCREEN SIZES
The smallest supported Very wide Unusual aspect ratios
WHAT TO AUTOMATE
Functional checks across the browser set.
WHAT TO CHECK MANUALLY
Appearance, which automation judges poorly.
WHAT VISUAL COMPARISON PROVIDES
Detection of layout changes across browsers.
WHAT TO DOCUMENT
The supported matrix, and what is unsupported.
