The four tests check the four ways of specifying a <details> tag is open or closed. Support for 2 and 3 vary, even within browsers which natively support <details>. The important thing is that tests 1 and 4 pass.

1. <details open="open">
   - Tested to work in FF & IE9
   - Tested to work in IE8 with html5shiv
   - Natively Supported by Chrome and Safari Mac
   - Do use this for open <details>
2. <details open="">
   - Supportive Chrome and Safari treat this like <details open="open">
   - Don't use this
3. <details open>
   - Unsupportive FireFox and Internet Explorer change this to <details open="">
   - Don't use this
4. <details>
   - No specification defaults to closed
   - Do use this for closed <details>

The fifth test demonstrates how details_shim() interacts with existing onclick handlers.

Additionally, These buttons test altering the open state via JavaScript

Test 1: should be open ...
AND IT IS!

Test 2: should be closed ...
BUT IT ISN'T!

Test 3: should be open ...
AND IT IS!

Test 4: should be closed ...
BUT IT ISN'T!

Test 5: should alert on click ...
BUT DID IT?