LanguageFeatures/nnbd/null_aware_operator_A17_t07.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 A null-shorting cascade expression e?..s translates as follows,
/// where x and y are fresh object level variables.
///  fn[k : Exp -> Exp] : Exp =>
///  let x = EXP(e) in x == null ? null : let y = EXP(x.s) in k(x)
///
/// @description Check that a null-shorting cascade expression e?..s translates
/// as follows, where x and y are fresh object level variables.
///  fn[k : Exp -> Exp] : Exp =>
///  let x = EXP(e) in x == null ? null : let y = EXP(x.s) in k(x)
/// Test e ?.. m().n()
/// @author sgrekhov@unipro.ru
/// @issue 39141
/// @issue 40959

// Requirements=nnbd-strong
import "../../Utils/expect.dart";
class A {
  int counter = 0;
  String m() {
    counter++;
    return "Lily was here";
  }
}

class C {
  A a1 = new A();
  A a2 = new A();
  int counter1 = 0;
  int counter2 = 0;

  A m1() {
    counter1++;
    return a1;
  }
  A m2() {
    counter2++;
    return a2;
  }
}

main() {
  C c1 = new C();
  var actual1 = c1 ?.. m1().m();
//                 ^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
//              ^
// [cfe] Operand of null-aware operation '?..' has type 'C' which excludes null.
  var expected = c1;
  Expect.equals(expected, actual1);
  Expect.equals(1, c1.m1().counter);

  var actual3 = c1
//              ^
// [cfe] Operand of null-aware operation '?..' has type 'C' which excludes null.
    ?.. m1().m()
//  ^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
    .. m2().m();
  Expect.equals(expected, actual3);
  Expect.equals(2, c1.m1().counter);
  Expect.equals(1, c1.m2().counter);

  C? c2 = null;
  var actual4 = c2 ?.. m1().m();
  Expect.isNull(actual4);

  var actual6 = c2
    ?.. m1().m()
    .. m2().m();
  Expect.isNull(actual6);

  c2 = new C();
  var actual7 = c2 ?.. m1().m();
//                 ^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
//              ^
// [cfe] Operand of null-aware operation '?..' has type 'C' which excludes null.
  var expected2 = c2;
  Expect.equals(expected2, actual7);
  Expect.equals(1, c2?.m1().counter);
//                   ^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
//                 ^
// [cfe] Operand of null-aware operation '?.' has type 'C' which excludes null.

  var actual9 = c2
//              ^
// [cfe] Operand of null-aware operation '?..' has type 'C' which excludes null.
      ?.. m1().m()
//    ^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
      .. m2().m();
  Expect.equals(expected2, actual9);
  Expect.equals(2, c2.m1().counter);
  Expect.equals(1, c2.m2().counter);
}