Language/Types/Function_Types/implements_function_t04.dart

// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

/**
 * @assertion A function is always an instance of some class that implements the
 * class Function and implements a call method with the same signature as the
 * function. All function types are subtypes of Function.
 * @description Checks that function literals implement the interface Function.
 * @author iefremov
 */
import "../../../Utils/expect.dart";

main() {
  Expect.isTrue(() {} is Function);
  Expect.isTrue((var x) {} is Function);

  Expect.isTrue(((var x) => null) is Function);
  Expect.isTrue(((int x) => x) is Function);
  Expect.isTrue((([var x]) => "aa") is Function);
  Expect.isTrue(((var x, int z, [Object? o, var v = 1]) => x + z + o + v) is Function);
  Expect.isTrue(((x, z, {o, v: 1}) => x + z + o + v) is Function);
}