LanguageFeatures/Super-mixins/implementation_t09.dart

// Copyright (c) 2018, 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 In a mixin declaration like
/// mixin A<X extends S, Y extends T> on B, C implements D, E { body }
/// the on clause declares the interfaces B and C as super-class constraints of
/// the mixin. Having a super-class constaint allows the mixin declaration
/// instance members to perform super-invocations (like super.foo()) if they are
/// allowed by a class implementing both B and C. The mixin introduced by A can
/// then only be applied to classes that implement both B and C.
///
/// @description Checks that mixin declaration can only be applied to classes
/// that implement both B and C.Test type parameters
/// @author sgrekhov@unipro.ru

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

class S {}
class T {}
class X extends S {}
class Y extends T {}

abstract class I {
  int get gi1;
}
abstract class J {
  int get gj1;
}

abstract class B<X extends S> {
  int get gb1;
  X? x;
}
abstract class C<Y extends T> {
  int get gc1;
  Y? y;
}

class A implements B<X>, C<Y> {
  int get gb1 => 1;
  int get gc1 => 2;
  X? x = new X();
  Y? y = new Y();
}

mixin M<X extends S, Y extends T> on B<X>, C<Y> implements I, J {
  int get gi1 => 3;
  int get gj1 => 4;
}

class MA extends A with M<X, Y> {
}

main() {
  MA ma = new MA();
  Expect.equals(1, ma.gb1);
  Expect.equals(2, ma.gc1);
  Expect.equals(3, ma.gi1);
  Expect.equals(4, ma.gj1);
  Expect.isTrue(ma.x is X);
  Expect.isTrue(ma.y is Y);
}