Why does GetAttribute("disabled") return "true" not "disabled"?

Question

In some of my tests I have to confirm that some select2 dropdowns are disabled when certain flags are set. To confirm this I found that the strategy below seemed to work:

Assert.True(element.GetAttribute("disabled").Equals("true"));

When I inspect the element I see disabled="disabled". My question is why does the string returned from GetAttribute = "true" not "disabled"?

Answer 1

https://selenium.googlecode.com/svn/trunk/docs/api/java/org/openqa/selenium/WebElement.html

Certain attributes seem to only return Boolean values, whether the actual value is "true" or "false". Disabled is one of them. Linked page lists all the attributes considered to be Boolean values, any other attribute should return the attribute's value.

Quoting the most relevant part of the linked page :

"The following are deemed to be "boolean" attributes, and will return either "true" or null: async, autofocus, autoplay, checked, compact, complete, controls, declare, defaultchecked, defaultselected, defer, disabled, draggable, ended, formnovalidate, hidden, indeterminate, iscontenteditable, ismap, itemscope, loop, multiple, muted, nohref, noresize, noshade, novalidate, nowrap, open, paused, pubdate, readonly, required, reversed, scoped, seamless, seeking, selected, spellcheck, truespeed, willvalidate ". [Selenium : WebElement.getAttribute()]