Test the file_stream_wrapper_get_instance_by_scheme() function.
function testGetInstanceByScheme() {
$instance = file_stream_wrapper_get_instance_by_scheme($this->scheme);
$this
->assertEqual($this->classname, get_class($instance), 'Got correct class type for dummy scheme.');
$instance = file_stream_wrapper_get_instance_by_scheme('public');
$this
->assertEqual('DrupalPublicStreamWrapper', get_class($instance), 'Got correct class type for public scheme.');
}