LanguageFeatures/Control-flow-collections/type_inference_A07_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 key type of an if-else map element is the
/// least upper bound of the key types of the "then" and "else" elements,
/// likewise for the value type.
///
/// @description Checks that the upwards inference key type of an if-else map
/// element is the least upper bound of the key types of the "then" and "else"
/// elements, likewise for the value type.
/// @author sgrekhov@unipro.ru

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

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

main() {
  var i = 1;
  var map1 = {
    new C(): new C(),
    if (i > 0) new B(): new B() else new B(): new A()
  };
  Expect.isTrue(map1 is Map<B, A>);
  Expect.runtimeIsType<Map<B, A>>(map1);

  var map2 = {
    "": "",
    if (i < 0) "": "" else "": 1,
  };
  Expect.isTrue(map2 is Map<String, Object>);
  Expect.runtimeIsType<Map<String, Object>>(map2);

  var map3 = {
    1: 1,
    if (i > 0) 3:3 else 3.14: 3,
    if (i < 0) 2: 2
  };
  Expect.isTrue(map3 is Map<num, int>);
  Expect.runtimeIsType<Map<num, int>>(map3);
}