Tests a basic rebuild with the user registration form.
function testUserRegistrationRebuild() {
$edit = array(
'name' => 'foo',
'mail' => 'bar@example.com',
);
$this
->drupalPost('user/register', $edit, 'Rebuild');
$this
->assertText('Form rebuilt.');
$this
->assertFieldByName('name', 'foo', 'Entered user name has been kept.');
$this
->assertFieldByName('mail', 'bar@example.com', 'Entered mail address has been kept.');
}