function runAsync () {
    if (runIndex++ < sampleSize) {
      fn.call(child, function () {
        setTimeout(runAsync, 0)
      })
    } else {
      setTimeout(finishChild, 0)
    }
  }
function runAsync () {
    if (runIndex++ < sampleSize) {
      fn.call(child, function () {
        setTimeout(runAsync, 0)
      })
    } else {
      setTimeout(finishChild, 0)
    }
  }
function runAsync ( ) { if ( runIndex ++ < sampleSize ) { fn . call ( child , function ( ) { setTimeout ( runAsync , 0 ) } ) } else { setTimeout ( finishChild , 0 ) } }
Run the current child's test function asynchronously.
Run the current child s test function asynchronously .