// Copyright 2014 The Flutter Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. import 'package:flutter_test/flutter_test.dart'; class X {} class Y extends X {} class A<U extends X> { U? u; } void main() { test('Assignment through a covariant template throws exception', () { final A<Y> ay = A<Y>(); final A<X> ayAsAx = ay; expect(() { ayAsAx.u = X(); }, throwsA(isA<TypeError>())); }); }