If you alter the path for user.login or user.logout, the helpers for logging in and logging out in a test are broken.
Example code
if ($id === 'user.login') {
$route->setPath('/login');
}
elseif ($id === 'user.logout') {
$route->setPath('/logout');
}
elseif ($id === 'user.reset.login') {
$route->setPath('/id/reset/{uid}/{timestamp}/{hash}/login');
}
elseif ($id === 'user.reset') {
$route->setPath('/id/reset/{uid}/{timestamp}/{hash}');
}
elseif ($id === 'user.reset.form') {
$route->setPath('/id/reset/{uid}');
}
You get a HTTP 400 error because the only route at /user/login is the HTTP POST method version.