LanguageFeatures/Control-flow-collections/type_inference_A12_t04.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 If element is a forElement with element e1 then:
///
/// Inference for the iterated expression and the controlling variable is done as
/// for the corresponding for or await for statement.
///
/// If the inferred set element type of e1 is S then the inferred set element
/// type of element is S.
///
/// @description Checks that if element is a forElement with element e1 then if
/// the inferred set element type of e1 is S then the inferred set element type
/// of element is S.
/// @author sgrekhov@unipro.ru

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

main() {
  var collection = [1, 2, 3, 4, 5];
  var c1 = [1, 2, 3] as List<int>?;
  var c2 = [1.1, 2.2, 3.3] as List<double>?;
  var set1 = {
    for (var i in collection)
      if (i.isEven) ...?c1 else ...?c2
  };
  Expect.isTrue(set1 is Set<num>);
  Expect.isFalse(set1 is Set<int>);
  Expect.isFalse(set1 is Set<double>);
  Expect.runtimeIsType<Set<num>>(set1);
  Expect.runtimeIsNotType<Set<int>>(set1);
  Expect.runtimeIsNotType<Set<double>>(set1);

  var set2 = {
    "",
    for (var i in collection)
      if (i.isEven) ...?c1 else ...?c2
  };
  Expect.isTrue(set2 is Set<Object>);
  Expect.isFalse(set2 is Set<int>);
  Expect.isFalse(set2 is Set<double>);
  Expect.runtimeIsType<Set<Object>>(set2);
  Expect.runtimeIsNotType<Set<int>>(set2);
  Expect.runtimeIsNotType<Set<double>>(set2);

  c1 = null;
  c2 = null;
  var set3 = {
    for (var i in collection)
      if (i.isEven) ...?c1 else ...?c2
  };
  Expect.isTrue(set3 is Set<num>);
  Expect.isFalse(set3 is Set<int>);
  Expect.isFalse(set3 is Set<double>);
  Expect.runtimeIsType<Set<num>>(set3);
  Expect.runtimeIsNotType<Set<int>>(set3);
  Expect.runtimeIsNotType<Set<double>>(set3);
}