Function run_singlethreaded_test 

pub fn run_singlethreaded_test<F, Fut, R>(test: F, options: TestOptions) -> R
where
    F: 'static + Sync + Fn(usize) -> Fut,
    Fut: 'static + Future<Output = R>,
    R: TestResult,

Runs a test in an executor, potentially repeatedly and concurrently.