   {
     let iterations = loopTestCount
 
-    measure {
+    measureMetrics([XCTPerformanceMetric_WallClockTime], automaticallyStartMeasuring: false) {
       let inputs = (1...iterations).map { Deferred(value: $0) }
+      self.startMeasuring()
       let c = reduce(inputs, initial: 0, combine: +)
       switch c.result
       {

      default:
        XCTFail()
      }
    }
  }

  func testPerformanceABAProneReduce()
  {
    let iterations = loopTestCount

    measure {
      let inputs = (1...iterations).map {Deferred(value: $0) }
      let accumulator = Deferred(value: 0)
      let c = inputs.reduce(accumulator) {
        (accumulator, deferred) in

      default:
        XCTFail()
      }
      self.stopMeasuring()
    }
  }
}
