     ("testPerformanceFuture", testPerformanceFuture)
     ]
 
-  static let runsRange = 0..<100000
+  static let runsRange: CountableRange<Int64> = 0..<100000
 
   func testConstantFutureWait() {
     self.measure {


  func testHugeMapping_Success() {
    self.measure {
      var futureValue: Future<Int> = future(success: 0)
      for _ in PerformanceTests.runsRange {
        futureValue = futureValue.map(executor: .immediate) { $0 + 1 }
      }


  func testHugeMapping_Failure() {
    self.measure {
      var futureValue: Future<Int64> = future(failure: TestError.testCode)
      for _ in PerformanceTests.runsRange {
        futureValue = futureValue.map(executor: .immediate) { $0 + 1 }
      }
