[test] execution test for effectful properties

Author: kavon

test/Concurrency/Runtime/effectful_properties.swift

@@ -0,0 +1,128 @@
+// RUN: %target-run-simple-swift(-parse-as-library -Xfrontend -enable-experimental-concurrency %import-libdispatch) | %FileCheck %s
+
+// REQUIRES: executable_test
+// REQUIRES: concurrency
+// REQUIRES: libdispatch
+
+enum GeneralError : Error {
+  case UnknownBallKind
+  case Todo
+}
+
+enum BallKind {
+  case MostLostV1
+  case Chromehard
+  case PT5
+  case KirksandLignature
+}
+
+class Specs {
+  // obtains the number of dimples
+  subscript(_ bk : BallKind) -> Int {
+    get throws {
+      switch (bk) {
+      case .MostLostV1:
+        return 450
+      case .Chromehard:
+        return 125
+      default:
+        throw GeneralError.UnknownBallKind
+      }
+    }
+  }
+}
+
+actor Database {
+  var currentData : Specs {
+    get async {
+      let handle = Task.runDetached { Specs() }
+      print("obtaining specs...")
+      return await handle.get()
+    }
+  }
+
+  var hasNewData : Bool {
+    get throws { return true }
+  }
+}
+
+protocol SphericalObject {
+  var name : String { get async throws }
+  var dimples : Int { get async throws }
+  var description : String { get async throws }
+}
+
+class Ball : SphericalObject {
+  var name : String { get async throws { throw GeneralError.Todo } }
+  var dimples : Int { get async throws { throw GeneralError.Todo } }
+  var description : String { get async throws { throw GeneralError.Todo } }
+}
+
+class GolfBall : Ball {
+  private static let db : Database = Database()
+
+  private var _model : BallKind
+  private var _dimples : Int?
+
+  init(_ bk : BallKind) {
+    _model = bk
+  }
+
+  override var name : String {
+    return "golf ball"
+  }
+
+  override var description : String {
+    get async throws {
+      return "this \(name) has \(await dimples) dimples"
+    }
+  }
+
+  override var dimples : Int {
+     get async {
+      let newData = (try? await GolfBall.db.hasNewData) ?? false
+
+      if newData || _dimples == nil {
+        let specs = await GolfBall.db.currentData
+        _dimples = (try? specs[_model]) ?? 0
+      }
+
+      return _dimples!
+    }
+  }
+}
+
+// CHECK: obtaining specs...
+// CHECK: this golf ball has 450 dimples
+// CHECK: obtaining specs...
+// CHECK: this golf ball has 125 dimples
+// CHECK: obtaining specs...
+// CHECK: this golf ball has 0 dimples
+// CHECK: obtaining specs...
+// CHECK: this golf ball has 0 dimples
+
+func printAsBall(_ b : Ball) async {
+  print(try! await b.description)
+}
+
+func printAsAsSphericalObject(_ b : SphericalObject) async {
+  print(try! await b.description)
+}
+
+@main struct RunIt {
+  static func main() async {
+    let balls : [(Bool, Ball)] = [
+      (true, GolfBall(.MostLostV1)),
+      (false, GolfBall(.Chromehard)),
+      (true, GolfBall(.PT5)),
+      (false, GolfBall(.KirksandLignature))
+    ]
+    for (useProtocol, ball) in balls {
+      if (useProtocol) {
+        await printAsAsSphericalObject(ball)
+      } else {
+        await printAsBall(ball)
+      }
+    }
+  }
+}