LanguageFeatures/Control-flow-collections/type_inference_A03_t01.dart

// Copyright (c) 2019, 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 The upwards inference element type of an if-else list element is
/// the least upper bound of the types of the "then" and "else" elements.
///
/// @description Checks that the upwards inference element type of an if-else
/// list element is the least upper bound of the types of the "then" and "else"
/// elements.
/// @author sgrekhov@unipro.ru

import "../../Utils/expect.dart";

class A {}
class B extends A {}
class C extends B {}

main() {
  var i = 1;
  var list1 = [
    new C(),
    if (i > 0) new B() else new A()
  ];
  Expect.isTrue(list1 is List<A>);
  Expect.runtimeIsType<List<A>>(list1);

  var list2 = [
    "",
    if (i < 0) "" else 1,
  ];
  Expect.isTrue(list2 is List<Object>);
  Expect.runtimeIsType<List<Object>>(list2);

  var list3 = [
    1,
    if (i > 0) 3 else 3.14,
    if (i < 0) 2
  ];
  Expect.isTrue(list3 is List<num>);
  Expect.runtimeIsType<List<num>>(list3);
}