When test run duration is less than 1 second, there is an error when we send result for this test into testrail.
It happens in method formatTime() of class Extension. If elapsed value is less than 1, then we change it to 0 and send result.
if ($time < 1.0) {
return '0s';
}
But 0 is not valid value for add_result method and we get an error "results.elapsed is not in a valid time span format".
In testrail version 5.5 was added support of milliseconds for elapsed param. So now we can send results in testrail with elapsed=0.04s