Not sure if it has changed since the accepted answer was accepted, but it is possible.
$location.search()
will return an object of key-value pairs, the same pairs as the query string. A key that has no value is just stored in the object as true. In this case, the object would be:
{"test_user_bLzgB": true}
You could access this value directly with $location.search().test_user_bLzgB
Example (with larger query string): http://fiddle.jshell.net/TheSharpieOne/yHv2p/4/show/?test_user_bLzgB&somethingElse&also&something=Somethingelse
Note: Due to hashes (as it will go to http://fiddle.jshell.net/#/url, which would create a new fiddle), this fiddle will not work in browsers that do not support js history (will not work in IE <10)
Edit:
As pointed out in the comments by @Naresh and @DavidTchepak, the $locationProvider
also needs to be configured properly: https://code.angularjs.org/1.2.23/docs/guide/$location#-location-service-configuration