How We Test

Modernizr's Feature detection approach

• Conformance testing (like WebKit layoutTests, Mozilla Mochitests, and W3C Test Suites) test the full range of functionality to make sure the browser handles all edge cases in the spec correctly
• Feature testing will run through behavior (like setting a value into localStorage and reading it out).
• Feature detection will lightly see if such a feature's API exists (!!window.localStorage)

Many browsers get 80-100% coverage on conformance tests. Even robust implementations that most developers are content with may only get 80%.

Modernizr aims to write the fastest executable test that satisfies the 90% use case of what a developer wants to use a feature for.

So if a light sniff of !!window.localStorage will give the same result as a run through a conformance test, then we'll use it. (In localStorage's case, it doesn't and we have much more trickery involved.)

Testing techniques

Testling is great for writing small tests that you can run on 30 different browsers in under a minute. Here are some testling feature tests we used to explore possible feature detects.

The Browserstack API is another great technique to try out some feature detects on a wide array of mobile phones. Look at node-browserstack for digging into that.

Browsers we test in

primary targets

• IE6 - IE10
• FF ESR, FF stable - FF Nightly
• Chrome stable - Chrome Canary
• Opera stable, Opera Next
• Safari 5.1, Webkit Nightly
• iOS4+
• Android 2.2+, Chrome on Android

secondary targets

• Safari 4
• WebOS
• WP7
• BB6
• Opera Mobile
• Kindle Fire

incomplete list of browsers that are lucky if they're compatible

• BB pre-6
• Opera Mini